diff --git a/Android.mk b/Android.mk
index 40209bd..6a72fec 100644
--- a/Android.mk
+++ b/Android.mk
@@ -2,6 +2,7 @@
 include $(CLEAR_VARS)
 
 LOCAL_SRC_FILES = \
+    mkvparser/mkvparser.cpp \
     vpx/src/vpx_codec.c \
     vpx/src/vpx_decoder.c \
     vpx/src/vpx_image.c \
diff --git a/mkvparser/mkvparser.cpp b/mkvparser/mkvparser.cpp
new file mode 100644
index 0000000..b4ce5b3
--- /dev/null
+++ b/mkvparser/mkvparser.cpp
@@ -0,0 +1,4516 @@
+// Copyright (c) 2010 The WebM project authors. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the LICENSE file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS.  All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+
+#include "mkvparser.hpp"
+#include <cassert>
+#include <cstring>
+#include <new>
+//#include <windows.h>
+//#include "odbgstream.hpp"
+//using std::endl;
+
+mkvparser::IMkvReader::~IMkvReader()
+{
+}
+
+
+void mkvparser::GetVersion(int& major, int& minor, int& build, int& revision)
+{
+    major = 1;
+    minor = 0;
+    build = 0;
+    revision = 4;
+}
+
+
+long long mkvparser::ReadUInt(IMkvReader* pReader, long long pos, long& len)
+{
+    assert(pReader);
+    assert(pos >= 0);
+
+    long long total, available;
+
+    long hr = pReader->Length(&total, &available);
+    assert(hr >= 0);
+    assert(pos < available);
+    assert((available - pos) >= 1);  //assume here max u-int len is 8
+
+    unsigned char b;
+
+    hr = pReader->Read(pos, 1, &b);
+    if (hr < 0)
+        return hr;
+
+    assert(hr == 0L);
+
+    if (b & 0x80)       //1000 0000
+    {
+        len = 1;
+        b &= 0x7F;      //0111 1111
+    }
+    else if (b & 0x40)  //0100 0000
+    {
+        len = 2;
+        b &= 0x3F;      //0011 1111
+    }
+    else if (b & 0x20)  //0010 0000
+    {
+        len = 3;
+        b &= 0x1F;      //0001 1111
+    }
+    else if (b & 0x10)  //0001 0000
+    {
+        len = 4;
+        b &= 0x0F;      //0000 1111
+    }
+    else if (b & 0x08)  //0000 1000
+    {
+        len = 5;
+        b &= 0x07;      //0000 0111
+    }
+    else if (b & 0x04)  //0000 0100
+    {
+        len = 6;
+        b &= 0x03;      //0000 0011
+    }
+    else if (b & 0x02)  //0000 0010
+    {
+        len = 7;
+        b &= 0x01;      //0000 0001
+    }
+    else
+    {
+        assert(b & 0x01);  //0000 0001
+        len = 8;
+        b = 0;             //0000 0000
+    }
+
+    assert((available - pos) >= len);
+
+    long long result = b;
+    ++pos;
+    for (long i = 1; i < len; ++i)
+    {
+        hr = pReader->Read(pos, 1, &b);
+
+        if (hr < 0)
+            return hr;
+
+        assert(hr == 0L);
+
+        result <<= 8;
+        result |= b;
+
+        ++pos;
+    }
+
+    return result;
+}
+
+
+long long mkvparser::GetUIntLength(
+    IMkvReader* pReader,
+    long long pos,
+    long& len)
+{
+    assert(pReader);
+    assert(pos >= 0);
+
+    long long total, available;
+
+    long hr = pReader->Length(&total, &available);
+    assert(hr >= 0);
+    assert(available <= total);
+
+    if (pos >= available)
+        return pos;  //too few bytes available
+
+    unsigned char b;
+
+    hr = pReader->Read(pos, 1, &b);
+
+    if (hr < 0)
+        return hr;
+
+    assert(hr == 0L);
+
+    if (b == 0)  //we can't handle u-int values larger than 8 bytes
+        return E_FILE_FORMAT_INVALID;
+
+    unsigned char m = 0x80;
+    len = 1;
+
+    while (!(b & m))
+    {
+        m >>= 1;
+        ++len;
+    }
+
+    return 0;  //success
+}
+
+
+long long mkvparser::SyncReadUInt(
+    IMkvReader* pReader,
+    long long pos,
+    long long stop,
+    long& len)
+{
+    assert(pReader);
+
+    if (pos >= stop)
+        return E_FILE_FORMAT_INVALID;
+
+    unsigned char b;
+
+    long hr = pReader->Read(pos, 1, &b);
+
+    if (hr < 0)
+        return hr;
+
+    if (hr != 0L)
+        return E_BUFFER_NOT_FULL;
+
+    if (b == 0)  //we can't handle u-int values larger than 8 bytes
+        return E_FILE_FORMAT_INVALID;
+
+    unsigned char m = 0x80;
+    len = 1;
+
+    while (!(b & m))
+    {
+        m >>= 1;
+        ++len;
+    }
+
+    if ((pos + len) > stop)
+        return E_FILE_FORMAT_INVALID;
+
+    long long result = b & (~m);
+    ++pos;
+
+    for (int i = 1; i < len; ++i)
+    {
+        hr = pReader->Read(pos, 1, &b);
+
+        if (hr < 0)
+            return hr;
+
+        if (hr != 0L)
+            return E_BUFFER_NOT_FULL;
+
+        result <<= 8;
+        result |= b;
+
+        ++pos;
+    }
+
+    return result;
+}
+
+
+long long mkvparser::UnserializeUInt(
+    IMkvReader* pReader,
+    long long pos,
+    long long size)
+{
+    assert(pReader);
+    assert(pos >= 0);
+    assert(size > 0);
+    assert(size <= 8);
+
+    long long result = 0;
+
+    for (long long i = 0; i < size; ++i)
+    {
+        unsigned char b;
+
+        const long hr = pReader->Read(pos, 1, &b);
+
+        if (hr < 0)
+            return hr;
+        result <<= 8;
+        result |= b;
+
+        ++pos;
+    }
+
+    return result;
+}
+
+
+float mkvparser::Unserialize4Float(
+    IMkvReader* pReader,
+    long long pos)
+{
+    assert(pReader);
+    assert(pos >= 0);
+
+    long long total, available;
+
+    long hr = pReader->Length(&total, &available);
+    assert(hr >= 0);
+    assert(available <= total);
+    assert((pos + 4) <= available);
+
+    float result;
+
+    unsigned char* const p = (unsigned char*)&result;
+    unsigned char* q = p + 4;
+
+    for (;;)
+    {
+        hr = pReader->Read(pos, 1, --q);
+        assert(hr == 0L);
+
+        if (q == p)
+            break;
+
+        ++pos;
+    }
+
+    return result;
+}
+
+
+double mkvparser::Unserialize8Double(
+    IMkvReader* pReader,
+    long long pos)
+{
+    assert(pReader);
+    assert(pos >= 0);
+
+    double result;
+
+    unsigned char* const p = (unsigned char*)&result;
+    unsigned char* q = p + 8;
+
+    for (;;)
+    {
+        const long hr = pReader->Read(pos, 1, --q);
+        assert(hr == 0L);
+
+        if (q == p)
+            break;
+
+        ++pos;
+    }
+
+    return result;
+}
+
+signed char mkvparser::Unserialize1SInt(
+    IMkvReader* pReader,
+    long long pos)
+{
+    assert(pReader);
+    assert(pos >= 0);
+
+    long long total, available;
+
+    long hr = pReader->Length(&total, &available);
+    assert(hr == 0);
+    assert(available <= total);
+    assert(pos < available);
+
+    signed char result;
+
+    hr = pReader->Read(pos, 1, (unsigned char*)&result);
+    assert(hr == 0);
+
+    return result;
+}
+
+short mkvparser::Unserialize2SInt(
+    IMkvReader* pReader,
+    long long pos)
+{
+    assert(pReader);
+    assert(pos >= 0);
+
+    long long total, available;
+
+    long hr = pReader->Length(&total, &available);
+    assert(hr >= 0);
+    assert(available <= total);
+    assert((pos + 2) <= available);
+
+    short result;
+
+    unsigned char* const p = (unsigned char*)&result;
+    unsigned char* q = p + 2;
+
+    for (;;)
+    {
+        hr = pReader->Read(pos, 1, --q);
+        assert(hr == 0L);
+
+        if (q == p)
+            break;
+
+        ++pos;
+    }
+
+    return result;
+}
+
+
+bool mkvparser::Match(
+    IMkvReader* pReader,
+    long long& pos,
+    unsigned long id_,
+    long long& val)
+
+{
+    assert(pReader);
+    assert(pos >= 0);
+
+    long long total, available;
+
+    long hr = pReader->Length(&total, &available);
+    assert(hr >= 0);
+    assert(available <= total);
+
+    long len;
+
+    const long long id = ReadUInt(pReader, pos, len);
+    assert(id >= 0);
+    assert(len > 0);
+    assert(len <= 8);
+    assert((pos + len) <= available);
+
+    if ((unsigned long)id != id_)
+        return false;
+
+    pos += len;  //consume id
+
+    const long long size = ReadUInt(pReader, pos, len);
+    assert(size >= 0);
+    assert(size <= 8);
+    assert(len > 0);
+    assert(len <= 8);
+    assert((pos + len) <= available);
+
+    pos += len;  //consume length of size of payload
+
+    val = UnserializeUInt(pReader, pos, size);
+    assert(val >= 0);
+
+    pos += size;  //consume size of payload
+
+    return true;
+}
+
+bool mkvparser::Match(
+    IMkvReader* pReader,
+    long long& pos,
+    unsigned long id_,
+    char*& val)
+{
+    assert(pReader);
+    assert(pos >= 0);
+
+    long long total, available;
+
+    long hr = pReader->Length(&total, &available);
+    assert(hr >= 0);
+    assert(available <= total);
+
+    long len;
+
+    const long long id = ReadUInt(pReader, pos, len);
+    assert(id >= 0);
+    assert(len > 0);
+    assert(len <= 8);
+    assert((pos + len) <= available);
+
+    if ((unsigned long)id != id_)
+        return false;
+
+    pos += len;  //consume id
+
+    const long long size_ = ReadUInt(pReader, pos, len);
+    assert(size_ >= 0);
+    assert(len > 0);
+    assert(len <= 8);
+    assert((pos + len) <= available);
+
+    pos += len;  //consume length of size of payload
+    assert((pos + size_) <= available);
+
+    const size_t size = static_cast<size_t>(size_);
+    val = new char[size+1];
+
+    for (size_t i = 0; i < size; ++i)
+    {
+        char c;
+
+        hr = pReader->Read(pos + i, 1, (unsigned char*)&c);
+        assert(hr == 0L);
+
+        val[i] = c;
+
+        if (c == '\0')
+            break;
+
+    }
+
+    val[size] = '\0';
+    pos += size_;  //consume size of payload
+
+    return true;
+}
+
+bool mkvparser::Match(
+    IMkvReader* pReader,
+    long long& pos,
+    unsigned long id_,
+    unsigned char*& buf,
+    size_t& buflen)
+{
+    assert(pReader);
+    assert(pos >= 0);
+
+    long long total, available;
+
+    long hr = pReader->Length(&total, &available);
+    assert(hr >= 0);
+    assert(available <= total);
+
+    long len;
+    const long long id = ReadUInt(pReader, pos, len);
+    assert(id >= 0);
+    assert(len > 0);
+    assert(len <= 8);
+    assert((pos + len) <= available);
+
+    if ((unsigned long)id != id_)
+        return false;
+
+    pos += len;  //consume id
+
+    const long long size_ = ReadUInt(pReader, pos, len);
+    assert(size_ >= 0);
+    assert(len > 0);
+    assert(len <= 8);
+    assert((pos + len) <= available);
+
+    pos += len;  //consume length of size of payload
+    assert((pos + size_) <= available);
+
+    const long buflen_ = static_cast<long>(size_);
+
+    buf = new (std::nothrow) unsigned char[buflen_];
+    assert(buf);  //TODO
+
+    hr = pReader->Read(pos, buflen_, buf);
+    assert(hr == 0L);
+
+    buflen = buflen_;
+
+    pos += size_;  //consume size of payload
+    return true;
+}
+
+
+bool mkvparser::Match(
+    IMkvReader* pReader,
+    long long& pos,
+    unsigned long id_,
+    double& val)
+{
+    assert(pReader);
+    assert(pos >= 0);
+
+    long long total, available;
+
+    long hr = pReader->Length(&total, &available);
+    assert(hr >= 0);
+    assert(available <= total);
+    long idlen;
+    const long long id = ReadUInt(pReader, pos, idlen);
+    assert(id >= 0);  //TODO
+
+    if ((unsigned long)id != id_)
+        return false;
+
+    long sizelen;
+    const long long size = ReadUInt(pReader, pos + idlen, sizelen);
+
+    switch (size)
+    {
+        case 4:
+        case 8:
+            break;
+        default:
+            return false;
+    }
+
+    pos += idlen + sizelen;  //consume id and size fields
+    assert((pos + size) <= available);
+
+    if (size == 4)
+        val = Unserialize4Float(pReader, pos);
+    else
+    {
+        assert(size == 8);
+        val = Unserialize8Double(pReader, pos);
+    }
+
+    pos += size;  //consume size of payload
+
+    return true;
+}
+
+
+bool mkvparser::Match(
+    IMkvReader* pReader,
+    long long& pos,
+    unsigned long id_,
+    short& val)
+{
+    assert(pReader);
+    assert(pos >= 0);
+
+    long long total, available;
+
+    long hr = pReader->Length(&total, &available);
+    assert(hr >= 0);
+    assert(available <= total);
+
+    long len;
+    const long long id = ReadUInt(pReader, pos, len);
+    assert(id >= 0);
+    assert((pos + len) <= available);
+
+    if ((unsigned long)id != id_)
+        return false;
+
+    pos += len;  //consume id
+
+    const long long size = ReadUInt(pReader, pos, len);
+    assert(size <= 2);
+    assert((pos + len) <= available);
+
+    pos += len;  //consume length of size of payload
+    assert((pos + size) <= available);
+
+    //TODO:
+    // Generalize this to work for any size signed int
+    if (size == 1)
+        val = Unserialize1SInt(pReader, pos);
+    else
+        val = Unserialize2SInt(pReader, pos);
+
+    pos += size;  //consume size of payload
+
+    return true;
+}
+
+
+namespace mkvparser
+{
+
+EBMLHeader::EBMLHeader():
+    m_docType(NULL)
+{
+}
+
+EBMLHeader::~EBMLHeader()
+{
+    delete[] m_docType;
+}
+
+long long EBMLHeader::Parse(
+    IMkvReader* pReader,
+    long long& pos)
+{
+    assert(pReader);
+
+    long long total, available;
+
+    long hr = pReader->Length(&total, &available);
+
+    if (hr < 0)
+        return hr;
+
+    pos = 0;
+    long long end = (1024 < available)? 1024: available;
+
+    for (;;)
+    {
+        unsigned char b = 0;
+
+        while (pos < end)
+        {
+            hr = pReader->Read(pos, 1, &b);
+
+            if (hr < 0)
+                return hr;
+
+            if (b == 0x1A)
+                break;
+
+            ++pos;
+        }
+
+        if (b != 0x1A)
+        {
+            if ((pos >= 1024) ||
+                (available >= total) ||
+                ((total - available) < 5))
+                  return -1;
+
+            return available + 5;  //5 = 4-byte ID + 1st byte of size
+        }
+
+        if ((total - pos) < 5)
+            return E_FILE_FORMAT_INVALID;
+
+        if ((available - pos) < 5)
+            return pos + 5;  //try again later
+
+        long len;
+
+        const long long result = ReadUInt(pReader, pos, len);
+
+        if (result < 0)  //error
+            return result;
+
+        if (result == 0x0A45DFA3)  //ReadId masks-off length indicator bits
+        {
+            assert(len == 4);
+            pos += len;
+            break;
+        }
+
+        ++pos;  //throw away just the 0x1A byte, and try again
+    }
+
+    long len;
+    long long result = GetUIntLength(pReader, pos, len);
+
+    if (result < 0)  //error
+        return result;
+
+    if (result > 0)  //need more data
+        return result;
+
+    assert(len > 0);
+    assert(len <= 8);
+
+    if ((total -  pos) < len)
+        return E_FILE_FORMAT_INVALID;
+    if ((available - pos) < len)
+        return pos + len;  //try again later
+
+    result = ReadUInt(pReader, pos, len);
+
+    if (result < 0)  //error
+        return result;
+
+    pos += len;  //consume u-int
+
+    if ((total - pos) < result)
+        return E_FILE_FORMAT_INVALID;
+
+    if ((available - pos) < result)
+        return pos + result;
+
+    end = pos + result;
+
+    m_version = 1;
+    m_readVersion = 1;
+    m_maxIdLength = 4;
+    m_maxSizeLength = 8;
+    m_docTypeVersion = 1;
+    m_docTypeReadVersion = 1;
+
+    while (pos < end)
+    {
+        if (Match(pReader, pos, 0x0286, m_version))
+            ;
+        else if (Match(pReader, pos, 0x02F7, m_readVersion))
+            ;
+        else if (Match(pReader, pos, 0x02F2, m_maxIdLength))
+            ;
+        else if (Match(pReader, pos, 0x02F3, m_maxSizeLength))
+            ;
+        else if (Match(pReader, pos, 0x0282, m_docType))
+            ;
+        else if (Match(pReader, pos, 0x0287, m_docTypeVersion))
+            ;
+        else if (Match(pReader, pos, 0x0285, m_docTypeReadVersion))
+            ;
+        else
+        {
+            result = ReadUInt(pReader, pos, len);
+            assert(result > 0);
+            assert(len > 0);
+            assert(len <= 8);
+
+            pos += len;
+            assert(pos < end);
+
+            result = ReadUInt(pReader, pos, len);
+            assert(result >= 0);
+            assert(len > 0);
+            assert(len <= 8);
+
+            pos += len + result;
+            assert(pos <= end);
+        }
+    }
+
+    assert(pos == end);
+
+    return 0;
+}
+
+
+Segment::Segment(
+    IMkvReader* pReader,
+    long long start,
+    long long size) :
+    m_pReader(pReader),
+    m_start(start),
+    m_size(size),
+    m_pos(start),
+    m_pInfo(NULL),
+    m_pTracks(NULL),
+    m_pCues(NULL),
+    m_clusters(NULL),
+    m_clusterCount(0),
+    m_clusterPreloadCount(0),
+    m_clusterSize(0)
+{
+}
+
+
+Segment::~Segment()
+{
+    const long count = m_clusterCount + m_clusterPreloadCount;
+
+    Cluster** i = m_clusters;
+    Cluster** j = m_clusters + count;
+
+    while (i != j)
+    {
+        Cluster* const p = *i++;
+        assert(p);
+
+        delete p;
+    }
+
+    delete[] m_clusters;
+
+    delete m_pTracks;
+    delete m_pInfo;
+    delete m_pCues;
+}
+
+
+long long Segment::CreateInstance(
+    IMkvReader* pReader,
+    long long pos,
+    Segment*& pSegment)
+{
+    assert(pReader);
+    assert(pos >= 0);
+
+    pSegment = NULL;
+
+    long long total, available;
+
+    long hr = pReader->Length(&total, &available);
+    assert(hr >= 0);
+    assert(available <= total);
+
+    //I would assume that in practice this loop would execute
+    //exactly once, but we allow for other elements (e.g. Void)
+    //to immediately follow the EBML header.  This is fine for
+    //the source filter case (since the entire file is available),
+    //but in the splitter case over a network we should probably
+    //just give up early.  We could for example decide only to
+    //execute this loop a maximum of, say, 10 times.
+
+    while (pos < total)
+    {
+        //Read ID
+
+        long len;
+        long long result = GetUIntLength(pReader, pos, len);
+
+        if (result)  //error, or too few available bytes
+            return result;
+
+        if ((pos + len) > total)
+            return E_FILE_FORMAT_INVALID;
+
+        if ((pos + len) > available)
+            return pos + len;
+
+        //TODO: if we liberalize the behavior of ReadUInt, we can
+        //probably eliminate having to use GetUIntLength here.
+        const long long id = ReadUInt(pReader, pos, len);
+
+        if (id < 0)  //error
+            return id;
+
+        pos += len;  //consume ID
+
+        //Read Size
+
+        result = GetUIntLength(pReader, pos, len);
+
+        if (result)  //error, or too few available bytes
+            return result;
+
+        if ((pos + len) > total)
+            return E_FILE_FORMAT_INVALID;
+
+        if ((pos + len) > available)
+            return pos + len;
+
+        //TODO: if we liberalize the behavior of ReadUInt, we can
+        //probably eliminate having to use GetUIntLength here.
+        const long long size = ReadUInt(pReader, pos, len);
+
+        if (size < 0)
+            return size;
+
+        pos += len;  //consume length of size of element
+
+        //Pos now points to start of payload
+
+        if ((pos + size) > total)
+            return E_FILE_FORMAT_INVALID;
+
+        if (id == 0x08538067)  //Segment ID
+        {
+            pSegment = new  Segment(pReader, pos, size);
+            assert(pSegment);  //TODO
+
+            return 0;    //success
+        }
+
+        pos += size;  //consume payload
+    }
+
+    assert(pos == total);
+
+    pSegment = new Segment(pReader, pos, 0);
+    assert(pSegment);  //TODO
+
+    return 0;  //success (sort of)
+}
+
+
+long long Segment::ParseHeaders()
+{
+    //Outermost (level 0) segment object has been constructed,
+    //and pos designates start of payload.  We need to find the
+    //inner (level 1) elements.
+    long long total, available;
+
+    long hr = m_pReader->Length(&total, &available);
+    assert(hr >= 0);
+    assert(available <= total);
+
+    const long long stop = m_start + m_size;
+    assert(stop <= total);
+    assert(m_pos <= stop);
+
+    bool bQuit = false;
+
+    while ((m_pos < stop) && !bQuit)
+    {
+        long long pos = m_pos;
+
+        long len;
+        long long result = GetUIntLength(m_pReader, pos, len);
+
+        if (result)  //error, or too few available bytes
+            return result;
+
+        if ((pos + len) > stop)
+            return E_FILE_FORMAT_INVALID;
+
+        if ((pos + len) > available)
+            return pos + len;
+
+        const long long idpos = pos;
+        const long long id = ReadUInt(m_pReader, idpos, len);
+
+        if (id < 0)  //error
+            return id;
+
+        pos += len;  //consume ID
+
+        //Read Size
+        result = GetUIntLength(m_pReader, pos, len);
+
+        if (result)  //error, or too few available bytes
+            return result;
+
+        if ((pos + len) > stop)
+            return E_FILE_FORMAT_INVALID;
+
+        if ((pos + len) > available)
+            return pos + len;
+
+        const long long size = ReadUInt(m_pReader, pos, len);
+
+        if (size < 0)
+            return size;
+
+        pos += len;  //consume length of size of element
+
+        //Pos now points to start of payload
+
+        if ((pos + size) > stop)
+            return E_FILE_FORMAT_INVALID;
+
+        //We read EBML elements either in total or nothing at all.
+
+        if ((pos + size) > available)
+            return pos + size;
+
+        if (id == 0x0549A966)  //Segment Info ID
+        {
+            assert(m_pInfo == NULL);
+
+            m_pInfo = new SegmentInfo(this, pos, size);
+            assert(m_pInfo);  //TODO
+        }
+        else if (id == 0x0654AE6B)  //Tracks ID
+        {
+            assert(m_pTracks == NULL);
+
+            m_pTracks = new Tracks(this, pos, size);
+            assert(m_pTracks);  //TODO
+        }
+        else if (id == 0x0C53BB6B)  //Cues ID
+        {
+            if (m_pCues == NULL)
+            {
+                m_pCues = new Cues(this, pos, size);
+                assert(m_pCues);  //TODO
+            }
+        }
+        else if (id == 0x014D9B74)  //SeekHead ID
+        {
+            ParseSeekHead(pos, size);
+        }
+        else if (id == 0x0F43B675)  //Cluster ID
+        {
+            bQuit = true;
+        }
+
+        if (!bQuit)
+            m_pos = pos + size;  //consume payload
+    }
+
+    assert(m_pos <= stop);
+
+    if (m_pInfo == NULL)  //TODO: liberalize this behavior
+        return E_FILE_FORMAT_INVALID;
+
+    if (m_pTracks == NULL)
+        return E_FILE_FORMAT_INVALID;
+
+    return 0;  //success
+}
+
+
+#if 0
+long Segment::ParseCluster(Cluster*& pCluster, long long& pos_) const
+{
+    pCluster = NULL;
+    pos_ = -1;
+
+    const long long stop = m_start + m_size;
+    assert(m_pos <= stop);
+
+    long long pos = m_pos;
+    long long off = -1;
+
+    while (pos < stop)
+    {
+        long len;
+        const long long idpos = pos;
+
+        const long long id = SyncReadUInt(m_pReader, pos, stop, len);
+
+        if (id < 0)  //error
+            return static_cast<long>(id);
+
+        if (id == 0)
+            return E_FILE_FORMAT_INVALID;
+
+        pos += len;  //consume id
+        assert(pos < stop);
+
+        const long long size = SyncReadUInt(m_pReader, pos, stop, len);
+
+        if (size < 0)  //error
+            return static_cast<long>(size);
+
+        pos += len;  //consume size
+        assert(pos <= stop);
+
+        if (size == 0)  //weird
+            continue;
+
+        //pos now points to start of payload
+
+        pos += size;  //consume payload
+        assert(pos <= stop);
+
+        if (id == 0x0F43B675)  //Cluster ID
+        {
+            off = idpos - m_start;  // >= 0 means we found a cluster
+            break;
+        }
+    }
+
+    assert(pos <= stop);
+
+    //Indicate to caller how much of file has been consumed. This is
+    //used later in AddCluster to adjust the current parse position
+    //(the value cached in the segment object itself) to the
+    //file position value just past the cluster we parsed.
+
+    if (off < 0)  //we did not found any more clusters
+    {
+        pos_ = stop;  //pos_ >= 0 here means EOF (cluster is NULL)
+        return 0;     //TODO: confirm this return value
+    }
+
+    //We found a cluster.  Now read something, to ensure that it is
+    //fully loaded in the network cache.
+
+    if (pos >= stop)  //we parsed the entire segment
+    {
+        //We did find a cluster, but it was very last element in the segment.
+        //Our preference is that the loop above runs 1 1/2 times:
+        //the first pass finds the cluster, and the second pass
+        //finds the element the follows the cluster.  In this case, however,
+        //we reached the end of the file without finding another element,
+        //so we didn't actually read anything yet associated with "end of the
+        //cluster".  And we must perform an actual read, in order
+        //to guarantee that all of the data that belongs to this
+        //cluster has been loaded into the network cache.  So instead
+        //of reading the next element that follows the cluster, we
+        //read the last byte of the cluster (which is also the last
+        //byte in the file).
+
+        //Read the last byte of the file. (Reading 0 bytes at pos
+        //might work too -- it would depend on how the reader is
+        //implemented.  Here we take the more conservative approach,
+        //since this makes fewer assumptions about the network
+        //reader abstraction.)
+
+        unsigned char b;
+
+        const int result = m_pReader->Read(pos - 1, 1, &b);
+        assert(result == 0);
+
+        pos_ = stop;
+    }
+    else
+    {
+        long len;
+        const long long idpos = pos;
+
+        const long long id = SyncReadUInt(m_pReader, pos, stop, len);
+
+        if (id < 0)  //error
+            return static_cast<long>(id);
+
+        if (id == 0)
+            return E_BUFFER_NOT_FULL;
+
+        pos += len;  //consume id
+        assert(pos < stop);
+
+        const long long size = SyncReadUInt(m_pReader, pos, stop, len);
+
+        if (size < 0)  //error
+            return static_cast<long>(size);
+
+        pos_ = idpos;
+    }
+
+    //We found a cluster, and it has been completely loaded into the
+    //network cache.  (We can guarantee this because we actually read
+    //the EBML tag that follows the cluster, or, if we reached EOF,
+    //because we actually read the last byte of the cluster).
+
+    Segment* const this_ = const_cast<Segment*>(this);
+
+    pCluster = Cluster::Parse(this_, m_clusterCount, off);
+    assert(pCluster);
+    assert(pCluster->m_index == m_clusterCount);
+
+    return 0;
+}
+
+
+bool Segment::AddCluster(Cluster* pCluster, long long pos)
+{
+    assert(pos >= m_start);
+
+    const long long stop = m_start + m_size;
+    assert(pos <= stop);
+
+    if (pCluster)
+    {
+        AppendCluster(pCluster);
+        assert(m_clusters);
+        assert(m_clusterSize > pCluster->m_index);
+        assert(m_clusters[pCluster->m_index] == pCluster);
+    }
+
+    m_pos = pos;  //m_pos >= stop is now we know we have all clusters
+
+    return (pos >= stop);
+}
+#endif
+
+
+long Segment::LoadCluster()
+{
+    const long long stop = m_start + m_size;
+
+    while (m_pos < stop)
+    {
+        long long pos = m_pos;
+
+        long len;
+
+        long long result = GetUIntLength(m_pReader, pos, len);
+
+        if (result < 0)  //error
+            return static_cast<long>(result);
+
+        if ((pos + len) > stop)
+            return E_FILE_FORMAT_INVALID;
+
+        const long long idpos = pos;
+        const long long id = ReadUInt(m_pReader, idpos, len);
+
+        if (id < 0)  //error
+            return static_cast<long>(id);
+
+        pos += len;  //consume ID
+
+        //Read Size
+        result = GetUIntLength(m_pReader, pos, len);
+
+        if (result < 0)  //error
+            return static_cast<long>(result);
+
+        if ((pos + len) > stop)
+            return E_FILE_FORMAT_INVALID;
+
+        const long long size = ReadUInt(m_pReader, pos, len);
+
+        if (size < 0)  //error
+            return static_cast<long>(size);
+
+        pos += len;  //consume length of size of element
+
+        if (size == 0)  //weird
+        {
+            m_pos = pos;
+            continue;
+        }
+
+        //Pos now points to start of payload
+
+        if ((pos + size) > stop)
+            return E_FILE_FORMAT_INVALID;
+
+        if (id == 0x0C53BB6B)  //Cues ID
+        {
+            if (m_pCues == NULL)
+            {
+                m_pCues = new Cues(this, pos, size);
+                assert(m_pCues);  //TODO
+            }
+
+            m_pos = pos + size;  //consume payload
+            continue;
+        }
+
+        if (id != 0x0F43B675)  //Cluster ID
+        {
+            m_pos = pos + size;  //consume payload
+            continue;
+        }
+
+        const long idx = m_clusterCount;
+        const long long idoff = idpos - m_start;
+
+        if (m_clusterPreloadCount > 0)
+        {
+            assert(idx < m_clusterSize);
+
+            Cluster* const pCluster = m_clusters[idx];
+            assert(pCluster);
+            assert(pCluster->m_index < 0);
+
+            const long long off_ = pCluster->m_pos;
+            assert(off_);
+
+            const long long off = off_ * ((off_ >= 0) ? 1 : -1);
+            assert(idoff <= off);
+
+            if (idoff == off)  //cluster has been preloaded already
+            {
+                pCluster->m_index = idx;
+                ++m_clusterCount;
+                --m_clusterPreloadCount;
+
+                m_pos = pos + size;  //consume payload
+                break;
+            }
+        }
+
+        Cluster* const pCluster = Cluster::Parse(this, idx, idoff);
+        assert(pCluster);
+        assert(pCluster->m_index == idx);
+
+        AppendCluster(pCluster);
+        assert(m_clusters);
+        assert(idx < m_clusterSize);
+        assert(m_clusters[idx] == pCluster);
+
+        m_pos = pos + size;  //consume payload
+        break;
+    }
+
+    assert(m_pos <= stop);
+    return 0;
+}
+
+
+void Segment::AppendCluster(Cluster* pCluster)
+{
+    assert(pCluster);
+    assert(pCluster->m_index >= 0);
+
+    const long count = m_clusterCount + m_clusterPreloadCount;
+
+    long& size = m_clusterSize;
+    assert(size >= count);
+
+    const long idx = pCluster->m_index;
+    assert(idx == m_clusterCount);
+
+    if (count >= size)
+    {
+        long n;
+
+        if (size > 0)
+            n = 2 * size;
+        else if (m_pInfo == 0)
+            n = 2048;
+        else
+        {
+            const long long ns = m_pInfo->GetDuration();
+
+            if (ns <= 0)
+                n = 2048;
+            else
+            {
+                const long long sec = (ns + 999999999LL) / 1000000000LL;
+                n = static_cast<long>(sec);
+            }
+        }
+
+        Cluster** const qq = new Cluster*[n];
+        Cluster** q = qq;
+
+        Cluster** p = m_clusters;
+        Cluster** const pp = p + count;
+
+        while (p != pp)
+            *q++ = *p++;
+
+        delete[] m_clusters;
+
+        m_clusters = qq;
+        size = n;
+    }
+
+    if (m_clusterPreloadCount > 0)
+    {
+        assert(m_clusters);
+
+        Cluster** const p = m_clusters + m_clusterCount;
+        assert(*p);
+        assert((*p)->m_index < 0);
+
+        Cluster** q = p + m_clusterPreloadCount;
+        assert(q < (m_clusters + size));
+
+        for (;;)
+        {
+            Cluster** const qq = q - 1;
+            assert((*qq)->m_index < 0);
+
+            *q = *qq;
+            q = qq;
+
+            if (q == p)
+                break;
+        }
+    }
+
+    m_clusters[idx] = pCluster;
+    ++m_clusterCount;
+}
+
+
+void Segment::PreloadCluster(Cluster* pCluster, ptrdiff_t idx)
+{
+    assert(pCluster);
+    assert(pCluster->m_index < 0);
+    assert(idx >= m_clusterCount);
+
+    const long count = m_clusterCount + m_clusterPreloadCount;
+
+    long& size = m_clusterSize;
+    assert(size >= count);
+
+    if (count >= size)
+    {
+        long n;
+
+        if (size > 0)
+            n = 2 * size;
+        else if (m_pInfo == 0)
+            n = 2048;
+        else
+        {
+            const long long ns = m_pInfo->GetDuration();
+
+            if (ns <= 0)
+                n = 2048;
+            else
+            {
+                const long long sec = (ns + 999999999LL) / 1000000000LL;
+                n = static_cast<long>(sec);
+            }
+        }
+
+        Cluster** const qq = new Cluster*[n];
+        Cluster** q = qq;
+
+        Cluster** p = m_clusters;
+        Cluster** const pp = p + count;
+
+        while (p != pp)
+            *q++ = *p++;
+
+        delete[] m_clusters;
+
+        m_clusters = qq;
+        size = n;
+    }
+
+    assert(m_clusters);
+
+    Cluster** const p = m_clusters + idx;
+
+    Cluster** q = m_clusters + count;
+    assert(q >= p);
+    assert(q < (m_clusters + size));
+
+    while (q > p)
+    {
+        Cluster** const qq = q - 1;
+        assert((*qq)->m_index < 0);
+
+        *q = *qq;
+        q = qq;
+    }
+
+    m_clusters[idx] = pCluster;
+    ++m_clusterPreloadCount;
+}
+
+
+long Segment::Load()
+{
+    assert(m_clusters == NULL);
+    assert(m_clusterSize == 0);
+    assert(m_clusterCount == 0);
+
+    //Outermost (level 0) segment object has been constructed,
+    //and pos designates start of payload.  We need to find the
+    //inner (level 1) elements.
+    const long long stop = m_start + m_size;
+
+#ifdef _DEBUG  //TODO: this is really Microsoft-specific
+    {
+        long long total, available;
+
+        long hr = m_pReader->Length(&total, &available);
+        assert(hr >= 0);
+        assert(available >= total);
+        assert(stop <= total);
+    }
+#endif
+
+    while (m_pos < stop)
+    {
+        long long pos = m_pos;
+
+        long len;
+
+        long long result = GetUIntLength(m_pReader, pos, len);
+
+        if (result < 0)  //error
+            return static_cast<long>(result);
+
+        if ((pos + len) > stop)
+            return E_FILE_FORMAT_INVALID;
+
+        const long long idpos = pos;
+        const long long id = ReadUInt(m_pReader, idpos, len);
+
+        if (id < 0)  //error
+            return static_cast<long>(id);
+
+        pos += len;  //consume ID
+
+        //Read Size
+        result = GetUIntLength(m_pReader, pos, len);
+
+        if (result < 0)  //error
+            return static_cast<long>(result);
+
+        if ((pos + len) > stop)
+            return E_FILE_FORMAT_INVALID;
+
+        const long long size = ReadUInt(m_pReader, pos, len);
+
+        if (size < 0)  //error
+            return static_cast<long>(size);
+
+        pos += len;  //consume length of size of element
+
+        //Pos now points to start of payload
+
+        if ((pos + size) > stop)
+            return E_FILE_FORMAT_INVALID;
+
+        if (id == 0x0F43B675)  //Cluster ID
+        {
+            const long idx = m_clusterCount;
+            const long long off = idpos - m_start;
+
+            Cluster* const pCluster = Cluster::Parse(this, idx, off);
+            assert(pCluster);
+            assert(pCluster->m_index == idx);
+
+            AppendCluster(pCluster);
+            assert(m_clusters);
+            assert(m_clusterSize > idx);
+            assert(m_clusters[idx] == pCluster);
+        }
+        else if (id == 0x0C53BB6B)  //Cues ID
+        {
+            assert(m_pCues == NULL);
+
+            m_pCues = new Cues(this, pos, size);
+            assert(m_pCues);  //TODO
+        }
+        else if (id == 0x0549A966)  //SegmentInfo ID
+        {
+            assert(m_pInfo == NULL);
+
+            m_pInfo = new  SegmentInfo(this, pos, size);
+            assert(m_pInfo);
+        }
+        else if (id == 0x0654AE6B)  //Tracks ID
+        {
+            assert(m_pTracks == NULL);
+
+            m_pTracks = new Tracks(this, pos, size);
+            assert(m_pTracks);  //TODO
+        }
+
+        m_pos = pos + size;  //consume payload
+    }
+
+    assert(m_pos >= stop);
+
+    if (m_pInfo == NULL)
+        return E_FILE_FORMAT_INVALID;  //TODO: ignore this case?
+
+    if (m_pTracks == NULL)
+        return E_FILE_FORMAT_INVALID;
+
+    if (m_clusters == NULL)  //TODO: ignore this case?
+        return E_FILE_FORMAT_INVALID;
+
+    //TODO: decide whether we require Cues element
+    //if (m_pCues == NULL)
+    //   return E_FILE_FORMAT_INVALID;
+
+    return 0;
+}
+
+
+void Segment::ParseSeekHead(long long start, long long size_)
+{
+    long long pos = start;
+    const long long stop = start + size_;
+
+    while (pos < stop)
+    {
+        long len;
+
+        const long long id = ReadUInt(m_pReader, pos, len);
+        assert(id >= 0);  //TODO
+        assert((pos + len) <= stop);
+
+        pos += len;  //consume ID
+
+        const long long size = ReadUInt(m_pReader, pos, len);
+        assert(size >= 0);
+        assert((pos + len) <= stop);
+
+        pos += len;  //consume Size field
+        assert((pos + size) <= stop);
+
+        if (id == 0x0DBB)  //SeekEntry ID
+            ParseSeekEntry(pos, size);
+
+        pos += size;  //consume payload
+        assert(pos <= stop);
+    }
+
+    assert(pos == stop);
+}
+
+
+void Segment::ParseCues(long long off)
+{
+    if (m_pCues)
+        return;
+
+    //odbgstream os;
+    //os << "Segment::ParseCues (begin)" << endl;
+
+    long long pos = m_start + off;
+    const long long stop = m_start + m_size;
+
+    long len;
+
+    long long result = GetUIntLength(m_pReader, pos, len);
+    assert(result == 0);
+    assert((pos + len) <= stop);
+
+    const long long idpos = pos;
+
+    const long long id = ReadUInt(m_pReader, idpos, len);
+    assert(id == 0x0C53BB6B);  //Cues ID
+
+    pos += len;  //consume ID
+    assert(pos < stop);
+
+    //Read Size
+
+    result = GetUIntLength(m_pReader, pos, len);
+    assert(result == 0);
+    assert((pos + len) <= stop);
+
+    const long long size = ReadUInt(m_pReader, pos, len);
+    assert(size >= 0);
+
+    pos += len;  //consume length of size of element
+    assert((pos + size) <= stop);
+
+    //Pos now points to start of payload
+
+    m_pCues = new Cues(this, pos, size);
+    assert(m_pCues);  //TODO
+
+    //os << "Segment::ParseCues (end)" << endl;
+}
+
+
+void Segment::ParseSeekEntry(
+   long long start,
+   long long size_)
+{
+    long long pos = start;
+
+    const long long stop = start + size_;
+
+    long len;
+
+    const long long seekIdId = ReadUInt(m_pReader, pos, len);
+    //seekIdId;
+    assert(seekIdId == 0x13AB);  //SeekID ID
+    assert((pos + len) <= stop);
+
+    pos += len;  //consume id
+
+    const long long seekIdSize = ReadUInt(m_pReader, pos, len);
+    assert(seekIdSize >= 0);
+    assert((pos + len) <= stop);
+
+    pos += len;  //consume size
+
+    const long long seekId = ReadUInt(m_pReader, pos, len);  //payload
+    assert(seekId >= 0);
+    assert(len == seekIdSize);
+    assert((pos + len) <= stop);
+
+    pos += seekIdSize;  //consume payload
+
+    const long long seekPosId = ReadUInt(m_pReader, pos, len);
+    //seekPosId;
+    assert(seekPosId == 0x13AC);  //SeekPos ID
+    assert((pos + len) <= stop);
+
+    pos += len;  //consume id
+
+    const long long seekPosSize = ReadUInt(m_pReader, pos, len);
+    assert(seekPosSize >= 0);
+    assert((pos + len) <= stop);
+
+    pos += len;  //consume size
+    assert((pos + seekPosSize) <= stop);
+
+    const long long seekOff = UnserializeUInt(m_pReader, pos, seekPosSize);
+    assert(seekOff >= 0);
+    assert(seekOff < m_size);
+
+    pos += seekPosSize;  //consume payload
+    assert(pos == stop);
+
+    const long long seekPos = m_start + seekOff;
+    assert(seekPos < (m_start + m_size));
+
+    if (seekId == 0x0C53BB6B)  //Cues ID
+        ParseCues(seekOff);
+}
+
+
+Cues::Cues(Segment* pSegment, long long start_, long long size_) :
+    m_pSegment(pSegment),
+    m_start(start_),
+    m_size(size_),
+    m_cue_points(NULL),
+    m_count(0),
+    m_preload_count(0),
+    m_pos(start_)
+{
+}
+
+
+Cues::~Cues()
+{
+    const size_t n = m_count + m_preload_count;
+
+    CuePoint** p = m_cue_points;
+    CuePoint** const q = p + n;
+
+    while (p != q)
+    {
+        CuePoint* const pCP = *p++;
+        assert(pCP);
+
+        delete pCP;
+    }
+
+    delete[] m_cue_points;
+}
+
+
+void Cues::Init() const
+{
+    if (m_cue_points)
+        return;
+
+    assert(m_count == 0);
+    assert(m_preload_count == 0);
+
+    IMkvReader* const pReader = m_pSegment->m_pReader;
+
+    const long long stop = m_start + m_size;
+    long long pos = m_start;
+
+    size_t cue_points_size = 0;
+
+    while (pos < stop)
+    {
+        const long long idpos = pos;
+
+        long len;
+
+        const long long id = ReadUInt(pReader, pos, len);
+        assert(id >= 0);  //TODO
+        assert((pos + len) <= stop);
+
+        pos += len;  //consume ID
+
+        const long long size = ReadUInt(pReader, pos, len);
+        assert(size >= 0);
+        assert((pos + len) <= stop);
+
+        pos += len;  //consume Size field
+        assert((pos + size) <= stop);
+
+        if (id == 0x3B)  //CuePoint ID
+            PreloadCuePoint(cue_points_size, idpos);
+
+        pos += size;  //consume payload
+        assert(pos <= stop);
+    }
+}
+
+
+void Cues::PreloadCuePoint(
+    size_t& cue_points_size,
+    long long pos) const
+{
+    assert(m_count == 0);
+
+    if (m_preload_count >= cue_points_size)
+    {
+        size_t n;
+
+        if (cue_points_size > 0)
+            n = static_cast<size_t>(2 * cue_points_size);
+        else
+        {
+            const SegmentInfo* const pInfo = m_pSegment->GetInfo();
+
+            if (pInfo == NULL)
+                n = 2048;
+            else
+            {
+                const long long ns = pInfo->GetDuration();
+
+                if (ns <= 0)
+                    n = 2048;
+                else
+                {
+                    const long long sec = (ns + 999999999LL) / 1000000000LL;
+                    n = static_cast<size_t>(sec);
+                }
+            }
+        }
+
+        CuePoint** const qq = new CuePoint*[n];
+        CuePoint** q = qq;  //beginning of target
+
+        CuePoint** p = m_cue_points;                //beginning of source
+        CuePoint** const pp = p + m_preload_count;  //end of source
+
+        while (p != pp)
+            *q++ = *p++;
+
+        delete[] m_cue_points;
+
+        m_cue_points = qq;
+        cue_points_size = n;
+    }
+
+    CuePoint* const pCP = new CuePoint(m_preload_count, pos);
+    m_cue_points[m_preload_count++] = pCP;
+}
+
+
+bool Cues::LoadCuePoint() const
+{
+    //odbgstream os;
+    //os << "Cues::LoadCuePoint" << endl;
+
+    const long long stop = m_start + m_size;
+
+    if (m_pos >= stop)
+        return false;  //nothing else to do
+
+    Init();
+
+    IMkvReader* const pReader = m_pSegment->m_pReader;
+
+    while (m_pos < stop)
+    {
+        const long long idpos = m_pos;
+
+        long len;
+
+        const long long id = ReadUInt(pReader, m_pos, len);
+        assert(id >= 0);  //TODO
+        assert((m_pos + len) <= stop);
+
+        m_pos += len;  //consume ID
+
+        const long long size = ReadUInt(pReader, m_pos, len);
+        assert(size >= 0);
+        assert((m_pos + len) <= stop);
+
+        m_pos += len;  //consume Size field
+        assert((m_pos + size) <= stop);
+
+        if (id != 0x3B)  //CuePoint ID
+        {
+            m_pos += size;  //consume payload
+            assert(m_pos <= stop);
+
+            continue;
+        }
+
+        assert(m_preload_count > 0);
+
+        CuePoint* const pCP = m_cue_points[m_count];
+        assert(pCP);
+        assert((pCP->GetTimeCode() >= 0) || (-pCP->GetTimeCode() == idpos));
+
+        pCP->Load(pReader);
+        ++m_count;
+        --m_preload_count;
+
+        m_pos += size;  //consume payload
+        assert(m_pos <= stop);
+
+        break;
+    }
+
+    return (m_pos < stop);
+}
+
+
+bool Cues::Find(
+    long long time_ns,
+    const Track* pTrack,
+    const CuePoint*& pCP,
+    const CuePoint::TrackPosition*& pTP) const
+{
+    assert(time_ns >= 0);
+    assert(pTrack);
+
+    LoadCuePoint();
+
+    assert(m_cue_points);
+    assert(m_count > 0);
+
+    CuePoint** const ii = m_cue_points;
+    CuePoint** i = ii;
+
+    CuePoint** const jj = ii + m_count + m_preload_count;
+    CuePoint** j = jj;
+
+    pCP = *i;
+    assert(pCP);
+
+    if (time_ns <= pCP->GetTime(m_pSegment))
+    {
+        pTP = pCP->Find(pTrack);
+        return (pTP != NULL);
+    }
+
+    IMkvReader* const pReader = m_pSegment->m_pReader;
+
+    while (i < j)
+    {
+        //INVARIANT:
+        //[ii, i) <= time_ns
+        //[i, j)  ?
+        //[j, jj) > time_ns
+
+        CuePoint** const k = i + (j - i) / 2;
+        assert(k < jj);
+
+        CuePoint* const pCP = *k;
+        assert(pCP);
+
+        pCP->Load(pReader);
+
+        const long long t = pCP->GetTime(m_pSegment);
+
+        if (t <= time_ns)
+            i = k + 1;
+        else
+            j = k;
+
+        assert(i <= j);
+    }
+
+    assert(i == j);
+    assert(i <= jj);
+    assert(i > ii);
+
+    pCP = *--i;
+    assert(pCP);
+    assert(pCP->GetTime(m_pSegment) <= time_ns);
+
+    //TODO: here and elsewhere, it's probably not correct to search
+    //for the cue point with this time, and then search for a matching
+    //track.  In principle, the matching track could be on some earlier
+    //cue point, and with our current algorithm, we'd miss it.  To make
+    //this bullet-proof, we'd need to create a secondary structure,
+    //with a list of cue points that apply to a track, and then search
+    //that track-based structure for a matching cue point.
+
+    pTP = pCP->Find(pTrack);
+    return (pTP != NULL);
+}
+
+
+#if 0
+bool Cues::FindNext(
+    long long time_ns,
+    const Track* pTrack,
+    const CuePoint*& pCP,
+    const CuePoint::TrackPosition*& pTP) const
+{
+    pCP = 0;
+    pTP = 0;
+
+    if (m_count == 0)
+        return false;
+
+    assert(m_cue_points);
+
+    const CuePoint* const* const ii = m_cue_points;
+    const CuePoint* const* i = ii;
+
+    const CuePoint* const* const jj = ii + m_count;
+    const CuePoint* const* j = jj;
+
+    while (i < j)
+    {
+        //INVARIANT:
+        //[ii, i) <= time_ns
+        //[i, j)  ?
+        //[j, jj) > time_ns
+
+        const CuePoint* const* const k = i + (j - i) / 2;
+        assert(k < jj);
+
+        pCP = *k;
+        assert(pCP);
+
+        const long long t = pCP->GetTime(m_pSegment);
+
+        if (t <= time_ns)
+            i = k + 1;
+        else
+            j = k;
+
+        assert(i <= j);
+    }
+
+    assert(i == j);
+    assert(i <= jj);
+
+    if (i >= jj)  //time_ns is greater than max cue point
+        return false;
+
+    pCP = *i;
+    assert(pCP);
+    assert(pCP->GetTime(m_pSegment) > time_ns);
+
+    pTP = pCP->Find(pTrack);
+    return (pTP != NULL);
+}
+#endif
+
+
+const CuePoint* Cues::GetFirst() const
+{
+    LoadCuePoint();  //init cues
+
+    const size_t count = m_count + m_preload_count;
+
+    if (count == 0)  //weird
+        return NULL;
+
+    CuePoint* const* const pp = m_cue_points;
+    assert(pp);
+
+    CuePoint* const pCP = pp[0];
+    assert(pCP);
+    assert(pCP->GetTimeCode() >= 0);
+
+    return pCP;
+}
+
+
+const CuePoint* Cues::GetLast() const
+{
+    LoadCuePoint();  //init cues
+
+    const size_t count = m_count + m_preload_count;
+
+    if (count == 0)  //weird
+        return NULL;
+
+    const size_t index = count - 1;
+
+    CuePoint* const* const pp = m_cue_points;
+    assert(pp);
+
+    CuePoint* const pCP = pp[index];
+    assert(pCP);
+
+    pCP->Load(m_pSegment->m_pReader);
+    assert(pCP->GetTimeCode() >= 0);
+
+    return pCP;
+}
+
+
+const CuePoint* Cues::GetNext(const CuePoint* pCurr) const
+{
+    if (pCurr == NULL)
+        return NULL;
+
+    assert(pCurr->GetTimeCode() >= 0);
+    assert(m_cue_points);
+    assert(m_count >= 1);
+
+    const size_t count = m_count + m_preload_count;
+
+    size_t index = pCurr->m_index;
+    assert(index < count);
+
+    CuePoint* const* const pp = m_cue_points;
+    assert(pp);
+    assert(pp[index] == pCurr);
+
+    ++index;
+
+    if (index >= count)
+        return NULL;
+
+    CuePoint* const pNext = pp[index];
+    assert(pNext);
+
+    pNext->Load(m_pSegment->m_pReader);
+
+    return pNext;
+}
+
+
+const BlockEntry* Cues::GetBlock(
+    const CuePoint* pCP,
+    const CuePoint::TrackPosition* pTP) const
+{
+    if (pCP == NULL)
+        return NULL;
+
+    if (pTP == NULL)
+        return NULL;
+
+    return m_pSegment->GetBlock(*pCP, *pTP);
+}
+
+
+const BlockEntry* Segment::GetBlock(
+    const CuePoint& cp,
+    const CuePoint::TrackPosition& tp)
+{
+    Cluster** const ii = m_clusters;
+    Cluster** i = ii;
+
+    const long count = m_clusterCount + m_clusterPreloadCount;
+
+    Cluster** const jj = ii + count;
+    Cluster** j = jj;
+
+    while (i < j)
+    {
+        //INVARIANT:
+        //[ii, i) < pTP->m_pos
+        //[i, j) ?
+        //[j, jj)  > pTP->m_pos
+
+        Cluster** const k = i + (j - i) / 2;
+        assert(k < jj);
+
+        Cluster* const pCluster = *k;
+        assert(pCluster);
+
+        const long long pos_ = pCluster->m_pos;
+        assert(pos_);
+
+        const long long pos = pos_ * ((pos_ < 0) ? -1 : 1);
+
+        if (pos < tp.m_pos)
+            i = k + 1;
+        else if (pos > tp.m_pos)
+            j = k;
+        else
+            return pCluster->GetEntry(cp, tp);
+    }
+
+    assert(i == j);
+
+    Cluster* const pCluster = Cluster::Parse(this, -1, tp.m_pos);
+    const ptrdiff_t idx = i - m_clusters;
+
+    PreloadCluster(pCluster, idx);
+    assert(m_clusters);
+    assert(m_clusterPreloadCount > 0);
+    assert(m_clusters[idx] == pCluster);
+
+    return pCluster->GetEntry(cp, tp);
+}
+
+
+
+CuePoint::CuePoint(size_t idx, long long pos) :
+    m_index(idx),
+    m_timecode(-1 * pos),
+    m_track_positions(NULL),
+    m_track_positions_count(0)
+{
+    assert(pos > 0);
+}
+
+
+CuePoint::~CuePoint()
+{
+    delete[] m_track_positions;
+}
+
+
+void CuePoint::Load(IMkvReader* pReader)
+{
+    //odbgstream os;
+    //os << "CuePoint::Load(begin): timecode=" << m_timecode << endl;
+
+    if (m_timecode >= 0)  //already loaded
+        return;
+
+    assert(m_track_positions == NULL);
+    assert(m_track_positions_count == 0);
+
+    long long pos_ = -m_timecode;
+
+    long long stop;
+
+    {
+        long len;
+
+        const long long id = ReadUInt(pReader, pos_, len);
+        assert(id == 0x3B);  //CuePoint ID
+        //assert((pos + len) <= stop);
+
+        pos_ += len;  //consume ID
+
+        const long long size = ReadUInt(pReader, pos_, len);
+        assert(size >= 0);
+        //assert((pos + len) <= stop);
+
+        pos_ += len;  //consume Size field
+        //assert((pos + size) <= stop);
+
+        //pos_ now points to start of payload
+
+        stop = pos_ + size;
+    }
+
+    long long pos = pos_;
+
+    //First count number of track positions
+
+    while (pos < stop)
+    {
+        long len;
+
+        const long long id = ReadUInt(pReader, pos, len);
+        assert(id >= 0);  //TODO
+        assert((pos + len) <= stop);
+
+        pos += len;  //consume ID
+
+        const long long size = ReadUInt(pReader, pos, len);
+        assert(size >= 0);
+        assert((pos + len) <= stop);
+
+        pos += len;  //consume Size field
+        assert((pos + size) <= stop);
+
+        if (id == 0x33)  //CueTime ID
+            m_timecode = UnserializeUInt(pReader, pos, size);
+
+        else if (id == 0x37) //CueTrackPosition(s) ID
+            ++m_track_positions_count;
+
+        pos += size;  //consume payload
+        assert(pos <= stop);
+    }
+
+    assert(m_timecode >= 0);
+    assert(m_track_positions_count > 0);
+
+    //os << "CuePoint::Load(cont'd): idpos=" << idpos
+    //   << " timecode=" << m_timecode
+    //   << endl;
+
+    m_track_positions = new TrackPosition[m_track_positions_count];
+
+    //Now parse track positions
+
+    TrackPosition* p = m_track_positions;
+    pos = pos_;
+
+    while (pos < stop)
+    {
+        long len;
+
+        const long long id = ReadUInt(pReader, pos, len);
+        assert(id >= 0);  //TODO
+        assert((pos + len) <= stop);
+
+        pos += len;  //consume ID
+
+        const long long size = ReadUInt(pReader, pos, len);
+        assert(size >= 0);
+        assert((pos + len) <= stop);
+
+        pos += len;  //consume Size field
+        assert((pos + size) <= stop);
+
+        if (id == 0x37) //CueTrackPosition(s) ID
+        {
+            TrackPosition& tp = *p++;
+            tp.Parse(pReader, pos, size);
+        }
+
+        pos += size;  //consume payload
+        assert(pos <= stop);
+    }
+
+    assert(size_t(p - m_track_positions) == m_track_positions_count);
+}
+
+
+
+void CuePoint::TrackPosition::Parse(
+    IMkvReader* pReader,
+    long long start_,
+    long long size_)
+{
+    const long long stop = start_ + size_;
+    long long pos = start_;
+
+    m_track = -1;
+    m_pos = -1;
+    m_block = 1;  //default
+
+    while (pos < stop)
+    {
+        long len;
+
+        const long long id = ReadUInt(pReader, pos, len);
+        assert(id >= 0);  //TODO
+        assert((pos + len) <= stop);
+
+        pos += len;  //consume ID
+
+        const long long size = ReadUInt(pReader, pos, len);
+        assert(size >= 0);
+        assert((pos + len) <= stop);
+
+        pos += len;  //consume Size field
+        assert((pos + size) <= stop);
+
+        if (id == 0x77)  //CueTrack ID
+            m_track = UnserializeUInt(pReader, pos, size);
+
+        else if (id == 0x71)  //CueClusterPos ID
+            m_pos = UnserializeUInt(pReader, pos, size);
+
+        else if (id == 0x1378)  //CueBlockNumber
+            m_block = UnserializeUInt(pReader, pos, size);
+
+        pos += size;  //consume payload
+        assert(pos <= stop);
+    }
+
+    assert(m_pos >= 0);
+    //assert(m_track > 0);
+    //assert(m_block > 0);
+}
+
+
+const CuePoint::TrackPosition* CuePoint::Find(const Track* pTrack) const
+{
+    assert(pTrack);
+
+    const long long n = pTrack->GetNumber();
+
+    const TrackPosition* i = m_track_positions;
+    const TrackPosition* const j = i + m_track_positions_count;
+
+    while (i != j)
+    {
+        const TrackPosition& p = *i++;
+
+        if (p.m_track == n)
+            return &p;
+    }
+
+    return NULL;  //no matching track number found
+}
+
+
+long long CuePoint::GetTimeCode() const
+{
+    return m_timecode;
+}
+
+long long CuePoint::GetTime(Segment* pSegment) const
+{
+    assert(pSegment);
+    assert(m_timecode >= 0);
+
+    const SegmentInfo* const pInfo = pSegment->GetInfo();
+    assert(pInfo);
+
+    const long long scale = pInfo->GetTimeCodeScale();
+    assert(scale >= 1);
+
+    const long long time = scale * m_timecode;
+
+    return time;
+}
+
+
+long long Segment::Unparsed() const
+{
+    const long long stop = m_start + m_size;
+
+    const long long result = stop - m_pos;
+    assert(result >= 0);
+
+    return result;
+}
+
+
+Cluster* Segment::GetFirst()
+{
+    if ((m_clusters == NULL) || (m_clusterCount <= 0))
+       return &m_eos;
+
+    Cluster* const pCluster = m_clusters[0];
+    assert(pCluster);
+
+    return pCluster;
+}
+
+
+Cluster* Segment::GetLast()
+{
+    if ((m_clusters == NULL) || (m_clusterCount <= 0))
+        return &m_eos;
+
+    const long idx = m_clusterCount - 1;
+
+    Cluster* const pCluster = m_clusters[idx];
+    assert(pCluster);
+
+    return pCluster;
+}
+
+
+unsigned long Segment::GetCount() const
+{
+    return m_clusterCount;
+}
+
+
+Cluster* Segment::GetNext(const Cluster* pCurr)
+{
+    assert(pCurr);
+    assert(pCurr != &m_eos);
+    assert(m_clusters);
+
+    long idx =  pCurr->m_index;
+
+    if (idx >= 0)
+    {
+        assert(m_clusterCount > 0);
+        assert(idx < m_clusterCount);
+        assert(pCurr == m_clusters[idx]);
+
+        ++idx;
+
+        if (idx >= m_clusterCount)
+            return &m_eos;  //caller will LoadCluster as desired
+
+        Cluster* const pNext = m_clusters[idx];
+        assert(pNext);
+        assert(pNext->m_index >= 0);
+        assert(pNext->m_index == idx);
+
+        return pNext;
+    }
+
+    assert(m_clusterPreloadCount > 0);
+
+    const long long off_ = pCurr->m_pos;
+    const long long off = off_ * ((off_ < 0) ? -1 : 1);
+
+    long long pos = m_start + off;
+    const long long stop = m_start + m_size;  //end of segment
+
+    {
+        long len;
+
+        long long result = GetUIntLength(m_pReader, pos, len);
+        assert(result == 0);  //TODO
+        assert((pos + len) <= stop);  //TODO
+
+        const long long id = ReadUInt(m_pReader, pos, len);
+        assert(id == 0x0F43B675);  //Cluster ID   //TODO
+
+        pos += len;  //consume ID
+
+        //Read Size
+        result = GetUIntLength(m_pReader, pos, len);
+        assert(result == 0);  //TODO
+        assert((pos + len) <= stop);  //TODO
+
+        const long long size = ReadUInt(m_pReader, pos, len);
+        assert(size > 0);  //TODO
+        assert((pCurr->m_size <= 0) || (pCurr->m_size == size));
+
+        pos += len;  //consume length of size of element
+        assert((pos + size) <= stop);  //TODO
+
+        //Pos now points to start of payload
+
+        pos += size;  //consume payload
+    }
+
+    long long off_next = 0;
+
+    while (pos < stop)
+    {
+        long len;
+
+        long long result = GetUIntLength(m_pReader, pos, len);
+        assert(result == 0);  //TODO
+        assert((pos + len) <= stop);  //TODO
+
+        const long long idpos = pos;  //pos of next (potential) cluster
+
+        const long long id = ReadUInt(m_pReader, idpos, len);
+        assert(id > 0);  //TODO
+
+        pos += len;  //consume ID
+
+        //Read Size
+        result = GetUIntLength(m_pReader, pos, len);
+        assert(result == 0);  //TODO
+        assert((pos + len) <= stop);  //TODO
+
+        const long long size = ReadUInt(m_pReader, pos, len);
+        assert(size >= 0);  //TODO
+
+        pos += len;  //consume length of size of element
+        assert((pos + size) <= stop);  //TODO
+
+        //Pos now points to start of payload
+
+        if (size == 0)  //weird
+            continue;
+
+        if (id == 0x0F43B675)  //Cluster ID
+        {
+            off_next = idpos - m_start;
+            break;
+        }
+
+        pos += size;  //consume payload
+    }
+
+    if (off_next <= 0)
+        return 0;
+
+    Cluster** const ii = m_clusters + m_clusterCount;
+    Cluster** i = ii;
+
+    Cluster** const jj = ii + m_clusterPreloadCount;
+    Cluster** j = jj;
+
+    while (i < j)
+    {
+        //INVARIANT:
+        //[0, i) < pos_next
+        //[i, j) ?
+        //[j, jj)  > pos_next
+
+        Cluster** const k = i + (j - i) / 2;
+        assert(k < jj);
+
+        Cluster* const pNext = *k;
+        assert(pNext);
+        assert(pNext->m_index < 0);
+
+        const long long pos_ = pNext->m_pos;
+        assert(pos_);
+
+        pos = pos_ * ((pos_ < 0) ? -1 : 1);
+
+        if (pos < off_next)
+            i = k + 1;
+        else if (pos > off_next)
+            j = k;
+        else
+            return pNext;
+    }
+
+    assert(i == j);
+
+    Cluster* const pNext = Cluster::Parse(this, -1, off_next);
+    const ptrdiff_t idx_next = i - m_clusters;  //insertion position
+
+    PreloadCluster(pNext, idx_next);
+    assert(m_clusters);
+    assert(idx_next < m_clusterSize);
+    assert(m_clusters[idx_next] == pNext);
+
+    return pNext;
+}
+
+
+Cluster* Segment::FindCluster(long long time_ns)
+{
+    if ((m_clusters == NULL) || (m_clusterCount <= 0))
+        return &m_eos;
+
+    {
+        Cluster* const pCluster = m_clusters[0];
+        assert(pCluster);
+        assert(pCluster->m_index == 0);
+
+        if (time_ns <= pCluster->GetTime())
+            return pCluster;
+    }
+
+    //Binary search of cluster array
+
+    long i = 0;
+    long j = m_clusterCount;
+
+    while (i < j)
+    {
+        //INVARIANT:
+        //[0, i) <= time_ns
+        //[i, j) ?
+        //[j, m_clusterCount)  > time_ns
+
+        const long k = i + (j - i) / 2;
+        assert(k < m_clusterCount);
+
+        Cluster* const pCluster = m_clusters[k];
+        assert(pCluster);
+        assert(pCluster->m_index == k);
+
+        const long long t = pCluster->GetTime();
+
+        if (t <= time_ns)
+            i = k + 1;
+        else
+            j = k;
+
+        assert(i <= j);
+    }
+
+    assert(i == j);
+    assert(i > 0);
+    assert(i <= m_clusterCount);
+
+    const long k = i - 1;
+
+    Cluster* const pCluster = m_clusters[k];
+    assert(pCluster);
+    assert(pCluster->m_index == k);
+    assert(pCluster->GetTime() <= time_ns);
+
+    return pCluster;
+}
+
+
+const BlockEntry* Segment::Seek(
+    long long time_ns,
+    const Track* pTrack)
+{
+    assert(pTrack);
+
+    if ((m_clusters == NULL) || (m_clusterCount <= 0))
+        return pTrack->GetEOS();
+
+    Cluster** const i = m_clusters;
+    assert(i);
+
+    {
+        Cluster* const pCluster = *i;
+        assert(pCluster);
+        assert(pCluster->m_index == 0);  //m_clusterCount > 0
+        assert(pCluster->m_pSegment == this);
+
+        if (time_ns <= pCluster->GetTime())
+            return pCluster->GetEntry(pTrack);
+    }
+
+    Cluster** const j = i + m_clusterCount;
+
+    if (pTrack->GetType() == 2)  //audio
+    {
+        //TODO: we could decide to use cues for this, as we do for video.
+        //But we only use it for video because looking around for a keyframe
+        //can get expensive.  Audio doesn't require anything special so a
+        //straight cluster search is good enough (we assume).
+
+        Cluster** lo = i;
+        Cluster** hi = j;
+
+        while (lo < hi)
+        {
+            //INVARIANT:
+            //[i, lo) <= time_ns
+            //[lo, hi) ?
+            //[hi, j)  > time_ns
+
+            Cluster** const mid = lo + (hi - lo) / 2;
+            assert(mid < hi);
+
+            Cluster* const pCluster = *mid;
+            assert(pCluster);
+            assert(pCluster->m_index == long(mid - m_clusters));
+            assert(pCluster->m_pSegment == this);
+
+            const long long t = pCluster->GetTime();
+
+            if (t <= time_ns)
+                lo = mid + 1;
+            else
+                hi = mid;
+
+            assert(lo <= hi);
+        }
+
+        assert(lo == hi);
+        assert(lo > i);
+        assert(lo <= j);
+
+        Cluster* const pCluster = *--lo;
+        assert(pCluster);
+        assert(pCluster->GetTime() <= time_ns);
+
+        return pCluster->GetEntry(pTrack);
+    }
+
+    assert(pTrack->GetType() == 1);  //video
+
+    Cluster** lo = i;
+    Cluster** hi = j;
+
+    while (lo < hi)
+    {
+        //INVARIANT:
+        //[i, lo) <= time_ns
+        //[lo, hi) ?
+        //[hi, j)  > time_ns
+
+        Cluster** const mid = lo + (hi - lo) / 2;
+        assert(mid < hi);
+
+        Cluster* const pCluster = *mid;
+        assert(pCluster);
+
+        const long long t = pCluster->GetTime();
+
+        if (t <= time_ns)
+            lo = mid + 1;
+        else
+            hi = mid;
+
+        assert(lo <= hi);
+    }
+
+    assert(lo == hi);
+    assert(lo > i);
+    assert(lo <= j);
+
+    Cluster* pCluster = *--lo;
+    assert(pCluster);
+    assert(pCluster->GetTime() <= time_ns);
+
+    {
+        const BlockEntry* const pBlockEntry = pCluster->GetEntry(pTrack);
+        assert(pBlockEntry);
+
+        if (!pBlockEntry->EOS())  //found a keyframe
+        {
+            const Block* const pBlock = pBlockEntry->GetBlock();
+            assert(pBlock);
+
+            //TODO: this isn't necessarily the keyframe we want,
+            //since there might another keyframe on this same
+            //cluster with a greater timecode that but that is
+            //still less than the requested time.  For now we
+            //simply return the first keyframe we find.
+
+            if (pBlock->GetTime(pCluster) <= time_ns)
+                return pBlockEntry;
+        }
+    }
+
+    const VideoTrack* const pVideo = static_cast<const VideoTrack*>(pTrack);
+
+    while (lo != i)
+    {
+        pCluster = *--lo;
+        assert(pCluster);
+        assert(pCluster->GetTime() <= time_ns);
+
+        const BlockEntry* const pBlockEntry = pCluster->GetMaxKey(pVideo);
+        assert(pBlockEntry);
+
+        if (!pBlockEntry->EOS())
+            return pBlockEntry;
+    }
+
+    //weird: we're on the first cluster, but no keyframe found
+    //should never happen but we must return something anyway
+
+    return pTrack->GetEOS();
+}
+
+
+#if 0
+bool Segment::SearchCues(
+    long long time_ns,
+    Track* pTrack,
+    Cluster*& pCluster,
+    const BlockEntry*& pBlockEntry,
+    const CuePoint*& pCP,
+    const CuePoint::TrackPosition*& pTP)
+{
+    if (pTrack->GetType() != 1)  //not video
+        return false;  //TODO: for now, just handle video stream
+
+    if (m_pCues == NULL)
+        return false;
+
+    if (!m_pCues->Find(time_ns, pTrack, pCP, pTP))
+        return false;  //weird
+
+    assert(pCP);
+    assert(pTP);
+    assert(pTP->m_track == pTrack->GetNumber());
+
+    //We have the cue point and track position we want,
+    //so we now need to search for the cluster having
+    //the indicated position.
+
+    return GetCluster(pCP, pTP, pCluster, pBlockEntry);
+}
+#endif
+
+
+Tracks* Segment::GetTracks() const
+{
+    return m_pTracks;
+}
+
+
+const SegmentInfo* Segment::GetInfo() const
+{
+    return m_pInfo;
+}
+
+
+const Cues* Segment::GetCues() const
+{
+    return m_pCues;
+}
+
+
+long long Segment::GetDuration() const
+{
+    assert(m_pInfo);
+    return m_pInfo->GetDuration();
+}
+
+
+SegmentInfo::SegmentInfo(Segment* pSegment, long long start, long long size_) :
+    m_pSegment(pSegment),
+    m_start(start),
+    m_size(size_),
+    m_pMuxingAppAsUTF8(NULL),
+    m_pWritingAppAsUTF8(NULL),
+    m_pTitleAsUTF8(NULL)
+{
+    IMkvReader* const pReader = m_pSegment->m_pReader;
+
+    long long pos = start;
+    const long long stop = start + size_;
+
+    m_timecodeScale = 1000000;
+    m_duration = -1;
+
+    while (pos < stop)
+    {
+        if (Match(pReader, pos, 0x0AD7B1, m_timecodeScale))
+            assert(m_timecodeScale > 0);
+
+        else if (Match(pReader, pos, 0x0489, m_duration))
+            assert(m_duration >= 0);
+
+        else if (Match(pReader, pos, 0x0D80, m_pMuxingAppAsUTF8))   //[4D][80]
+            assert(m_pMuxingAppAsUTF8);
+
+        else if (Match(pReader, pos, 0x1741, m_pWritingAppAsUTF8))  //[57][41]
+            assert(m_pWritingAppAsUTF8);
+
+        else if (Match(pReader, pos, 0x3BA9, m_pTitleAsUTF8))       //[7B][A9]
+            assert(m_pTitleAsUTF8);
+
+        else
+        {
+            long len;
+
+            const long long id = ReadUInt(pReader, pos, len);
+            //id;
+            assert(id >= 0);
+            assert((pos + len) <= stop);
+
+            pos += len;  //consume id
+            assert((stop - pos) > 0);
+
+            const long long size = ReadUInt(pReader, pos, len);
+            assert(size >= 0);
+            assert((pos + len) <= stop);
+
+            pos += len + size;  //consume size and payload
+            assert(pos <= stop);
+        }
+    }
+
+    assert(pos == stop);
+}
+
+SegmentInfo::~SegmentInfo()
+{
+    if (m_pMuxingAppAsUTF8)
+    {
+        delete[] m_pMuxingAppAsUTF8;
+        m_pMuxingAppAsUTF8 = NULL;
+    }
+
+    if (m_pWritingAppAsUTF8)
+    {
+        delete[] m_pWritingAppAsUTF8;
+        m_pWritingAppAsUTF8 = NULL;
+    }
+
+    if (m_pTitleAsUTF8)
+    {
+        delete[] m_pTitleAsUTF8;
+        m_pTitleAsUTF8 = NULL;
+    }
+}
+
+long long SegmentInfo::GetTimeCodeScale() const
+{
+    return m_timecodeScale;
+}
+
+
+long long SegmentInfo::GetDuration() const
+{
+    if (m_duration < 0)
+        return -1;
+
+    assert(m_timecodeScale >= 1);
+
+    const double dd = double(m_duration) * double(m_timecodeScale);
+    const long long d = static_cast<long long>(dd);
+
+    return d;
+}
+
+const char* SegmentInfo::GetMuxingAppAsUTF8() const
+{
+    return m_pMuxingAppAsUTF8;
+}
+
+
+const char* SegmentInfo::GetWritingAppAsUTF8() const
+{
+    return m_pWritingAppAsUTF8;
+}
+
+const char* SegmentInfo::GetTitleAsUTF8() const
+{
+    return m_pTitleAsUTF8;
+}
+
+Track::Track(Segment* pSegment, const Info& i) :
+    m_pSegment(pSegment),
+    m_info(i)
+{
+}
+
+Track::~Track()
+{
+    Info& info = const_cast<Info&>(m_info);
+    info.Clear();
+}
+
+Track::Info::Info():
+    type(-1),
+    number(-1),
+    uid(-1),
+    nameAsUTF8(NULL),
+    codecId(NULL),
+    codecPrivate(NULL),
+    codecPrivateSize(0),
+    codecNameAsUTF8(NULL)
+{
+}
+
+
+void Track::Info::Clear()
+{
+    delete[] nameAsUTF8;
+    nameAsUTF8 = NULL;
+
+    delete[] codecId;
+    codecId = NULL;
+
+    delete[] codecPrivate;
+    codecPrivate = NULL;
+
+    codecPrivateSize = 0;
+
+    delete[] codecNameAsUTF8;
+    codecNameAsUTF8 = NULL;
+}
+
+const BlockEntry* Track::GetEOS() const
+{
+    return &m_eos;
+}
+
+long long Track::GetType() const
+{
+    return m_info.type;
+}
+
+long long Track::GetNumber() const
+{
+    return m_info.number;
+}
+
+const char* Track::GetNameAsUTF8() const
+{
+    return m_info.nameAsUTF8;
+}
+
+const char* Track::GetCodecNameAsUTF8() const
+{
+    return m_info.codecNameAsUTF8;
+}
+
+
+const char* Track::GetCodecId() const
+{
+    return m_info.codecId;
+}
+
+const unsigned char* Track::GetCodecPrivate(size_t& size) const
+{
+    size = m_info.codecPrivateSize;
+    return m_info.codecPrivate;
+}
+
+
+long Track::GetFirst(const BlockEntry*& pBlockEntry) const
+{
+    Cluster* pCluster = m_pSegment->GetFirst();
+
+    //If Segment::GetFirst returns NULL, then this must be a network
+    //download, and we haven't loaded any clusters yet.  In this case,
+    //returning NULL from Track::GetFirst means the same thing.
+
+    for (int i = 0; i < 100; ++i)  //arbitrary upper bound
+    {
+        if (pCluster == NULL)
+        {
+            pBlockEntry = GetEOS();
+            return 1;
+        }
+
+        if (pCluster->EOS())
+        {
+            if (m_pSegment->Unparsed() <= 0)  //all clusters have been loaded
+            {
+                pBlockEntry = GetEOS();
+                return 1;
+            }
+
+            pBlockEntry = 0;
+            return E_BUFFER_NOT_FULL;
+        }
+
+        pBlockEntry = pCluster->GetFirst();
+
+        while (pBlockEntry)
+        {
+            const Block* const pBlock = pBlockEntry->GetBlock();
+            assert(pBlock);
+
+            if (pBlock->GetTrackNumber() == m_info.number)
+                return 0;
+
+            pBlockEntry = pCluster->GetNext(pBlockEntry);
+        }
+
+        pCluster = m_pSegment->GetNext(pCluster);
+    }
+
+    //NOTE: if we get here, it means that we didn't find a block with
+    //a matching track number.  We interpret that as an error (which
+    //might be too conservative).
+
+    pBlockEntry = GetEOS();  //so we can return a non-NULL value
+    return 1;
+}
+
+
+long Track::GetNext(
+    const BlockEntry* pCurrEntry,
+    const BlockEntry*& pNextEntry) const
+{
+    assert(pCurrEntry);
+    assert(!pCurrEntry->EOS());  //?
+
+    const Block* const pCurrBlock = pCurrEntry->GetBlock();
+    assert(pCurrBlock->GetTrackNumber() == m_info.number);
+
+    Cluster* pCluster = pCurrEntry->GetCluster();
+    assert(pCluster);
+    assert(!pCluster->EOS());
+
+    pNextEntry = pCluster->GetNext(pCurrEntry);
+
+    for (int i = 0; i < 100; ++i)  //arbitrary upper bound to search
+    {
+        while (pNextEntry)
+        {
+            const Block* const pNextBlock = pNextEntry->GetBlock();
+            assert(pNextBlock);
+
+            if (pNextBlock->GetTrackNumber() == m_info.number)
+                return 0;
+
+            pNextEntry = pCluster->GetNext(pNextEntry);
+        }
+
+        pCluster = m_pSegment->GetNext(pCluster);
+
+        if (pCluster == NULL)
+        {
+            pNextEntry = GetEOS();
+            return 1;
+        }
+
+        if (pCluster->EOS())
+        {
+            if (m_pSegment->Unparsed() <= 0)   //all clusters have been loaded
+            {
+                pNextEntry = GetEOS();
+                return 1;
+            }
+
+            //TODO: there is a potential O(n^2) problem here: we tell the
+            //caller to (pre)load another cluster, which he does, but then he
+            //calls GetNext again, which repeats the same search.  This is
+            //a pathological case, since the only way it can happen is if
+            //there exists a long sequence of clusters none of which contain a
+            // block from this track.  One way around this problem is for the
+            //caller to be smarter when he loads another cluster: don't call
+            //us back until you have a cluster that contains a block from this
+            //track. (Of course, that's not cheap either, since our caller
+            //would have to scan the each cluster as it's loaded, so that
+            //would just push back the problem.)
+
+            pNextEntry = NULL;
+            return E_BUFFER_NOT_FULL;
+        }
+
+        pNextEntry = pCluster->GetFirst();
+    }
+
+    //NOTE: if we get here, it means that we didn't find a block with
+    //a matching track number after lots of searching, so we give
+    //up trying.
+
+    pNextEntry = GetEOS();  //so we can return a non-NULL value
+    return 1;
+}
+
+
+Track::EOSBlock::EOSBlock()
+{
+}
+
+
+bool Track::EOSBlock::EOS() const
+{
+    return true;
+}
+
+
+Cluster* Track::EOSBlock::GetCluster() const
+{
+    return NULL;
+}
+
+
+size_t Track::EOSBlock::GetIndex() const
+{
+    return 0;
+}
+
+
+const Block* Track::EOSBlock::GetBlock() const
+{
+    return NULL;
+}
+
+
+bool Track::EOSBlock::IsBFrame() const
+{
+    return false;
+}
+
+
+VideoTrack::VideoTrack(Segment* pSegment, const Info& i) :
+    Track(pSegment, i),
+    m_width(-1),
+    m_height(-1),
+    m_rate(-1)
+{
+    assert(i.type == 1);
+    assert(i.number > 0);
+
+    IMkvReader* const pReader = pSegment->m_pReader;
+
+    const Settings& s = i.settings;
+    assert(s.start >= 0);
+    assert(s.size >= 0);
+
+    long long pos = s.start;
+    assert(pos >= 0);
+
+    const long long stop = pos + s.size;
+
+    while (pos < stop)
+    {
+#ifdef _DEBUG
+        long len;
+        const long long id = ReadUInt(pReader, pos, len);
+        assert(id >= 0);  //TODO: handle error case
+        assert((pos + len) <= stop);
+#endif
+        if (Match(pReader, pos, 0x30, m_width))
+            ;
+        else if (Match(pReader, pos, 0x3A, m_height))
+            ;
+        else if (Match(pReader, pos, 0x0383E3, m_rate))
+            ;
+        else
+        {
+            long len;
+            const long long id = ReadUInt(pReader, pos, len);
+            assert(id >= 0);  //TODO: handle error case
+            assert((pos + len) <= stop);
+
+            pos += len;  //consume id
+
+            const long long size = ReadUInt(pReader, pos, len);
+            assert(size >= 0);  //TODO: handle error case
+            assert((pos + len) <= stop);
+
+            pos += len;  //consume length of size
+            assert((pos + size) <= stop);
+
+            //pos now designates start of payload
+
+            pos += size;  //consume payload
+            assert(pos <= stop);
+        }
+    }
+
+    return;
+}
+
+
+bool VideoTrack::VetEntry(const BlockEntry* pBlockEntry) const
+{
+    assert(pBlockEntry);
+
+    const Block* const pBlock = pBlockEntry->GetBlock();
+    assert(pBlock);
+    assert(pBlock->GetTrackNumber() == m_info.number);
+
+    return pBlock->IsKey();
+}
+
+
+long long VideoTrack::GetWidth() const
+{
+    return m_width;
+}
+
+
+long long VideoTrack::GetHeight() const
+{
+    return m_height;
+}
+
+
+double VideoTrack::GetFrameRate() const
+{
+    return m_rate;
+}
+
+
+AudioTrack::AudioTrack(Segment* pSegment, const Info& i) :
+    Track(pSegment, i),
+    m_rate(0.0),
+    m_channels(0),
+    m_bitDepth(-1)
+{
+    assert(i.type == 2);
+    assert(i.number > 0);
+
+    IMkvReader* const pReader = pSegment->m_pReader;
+
+    const Settings& s = i.settings;
+    assert(s.start >= 0);
+    assert(s.size >= 0);
+
+    long long pos = s.start;
+    assert(pos >= 0);
+
+    const long long stop = pos + s.size;
+
+    while (pos < stop)
+    {
+#ifdef _DEBUG
+        long len;
+        const long long id = ReadUInt(pReader, pos, len);
+        assert(id >= 0);  //TODO: handle error case
+        assert((pos + len) <= stop);
+#endif
+        if (Match(pReader, pos, 0x35, m_rate))
+            ;
+        else if (Match(pReader, pos, 0x1F, m_channels))
+            ;
+        else if (Match(pReader, pos, 0x2264, m_bitDepth))
+            ;
+        else
+        {
+            long len;
+            const long long id = ReadUInt(pReader, pos, len);
+            assert(id >= 0);  //TODO: handle error case
+            assert((pos + len) <= stop);
+
+            pos += len;  //consume id
+
+            const long long size = ReadUInt(pReader, pos, len);
+            assert(size >= 0);  //TODO: handle error case
+            assert((pos + len) <= stop);
+
+            pos += len;  //consume length of size
+            assert((pos + size) <= stop);
+
+            //pos now designates start of payload
+
+            pos += size;  //consume payload
+            assert(pos <= stop);
+        }
+    }
+
+    return;
+}
+
+
+bool AudioTrack::VetEntry(const BlockEntry* pBlockEntry) const
+{
+    assert(pBlockEntry);
+
+    const Block* const pBlock = pBlockEntry->GetBlock();
+    assert(pBlock);
+    assert(pBlock->GetTrackNumber() == m_info.number);
+
+    return true;
+}
+
+
+double AudioTrack::GetSamplingRate() const
+{
+    return m_rate;
+}
+
+
+long long AudioTrack::GetChannels() const
+{
+    return m_channels;
+}
+
+long long AudioTrack::GetBitDepth() const
+{
+    return m_bitDepth;
+}
+
+Tracks::Tracks(Segment* pSegment, long long start, long long size_) :
+    m_pSegment(pSegment),
+    m_start(start),
+    m_size(size_),
+    m_trackEntries(NULL),
+    m_trackEntriesEnd(NULL)
+{
+    long long stop = m_start + m_size;
+    IMkvReader* const pReader = m_pSegment->m_pReader;
+
+    long long pos1 = m_start;
+    int count = 0;
+
+    while (pos1 < stop)
+    {
+        long len;
+        const long long id = ReadUInt(pReader, pos1, len);
+        assert(id >= 0);
+        assert((pos1 + len) <= stop);
+
+        pos1 += len;  //consume id
+
+        const long long size = ReadUInt(pReader, pos1, len);
+        assert(size >= 0);
+        assert((pos1 + len) <= stop);
+
+        pos1 += len;  //consume length of size
+
+        //pos now desinates start of element
+        if (id == 0x2E)  //TrackEntry ID
+            ++count;
+
+        pos1 += size;  //consume payload
+        assert(pos1 <= stop);
+    }
+
+    if (count <= 0)
+        return;
+
+    m_trackEntries = new Track*[count];
+    m_trackEntriesEnd = m_trackEntries;
+
+    long long pos = m_start;
+
+    while (pos < stop)
+    {
+        long len;
+        const long long id = ReadUInt(pReader, pos, len);
+        assert(id >= 0);
+        assert((pos + len) <= stop);
+
+        pos += len;  //consume id
+
+        const long long size1 = ReadUInt(pReader, pos, len);
+        assert(size1 >= 0);
+        assert((pos + len) <= stop);
+
+        pos += len;  //consume length of size
+
+        //pos now desinates start of element
+
+        if (id == 0x2E)  //TrackEntry ID
+            ParseTrackEntry(pos, size1, *m_trackEntriesEnd++);
+
+        pos += size1;  //consume payload
+        assert(pos <= stop);
+    }
+}
+
+
+unsigned long Tracks::GetTracksCount() const
+{
+    const ptrdiff_t result = m_trackEntriesEnd - m_trackEntries;
+    assert(result >= 0);
+
+    return static_cast<unsigned long>(result);
+}
+
+
+void Tracks::ParseTrackEntry(
+    long long start,
+    long long size,
+    Track*& pTrack)
+{
+    IMkvReader* const pReader = m_pSegment->m_pReader;
+
+    long long pos = start;
+    const long long stop = start + size;
+
+    Track::Info i;
+
+    Track::Settings videoSettings;
+    videoSettings.start = -1;
+    videoSettings.size = 0;
+
+    Track::Settings audioSettings;
+    audioSettings.start = -1;
+    audioSettings.size = 0;
+
+    while (pos < stop)
+    {
+#ifdef _DEBUG
+        long len;
+        const long long id = ReadUInt(pReader, pos, len);
+        len;
+        id;
+#endif
+        if (Match(pReader, pos, 0x57, i.number))
+            assert(i.number > 0);
+        else if (Match(pReader, pos, 0x33C5, i.uid))
+            ;
+        else if (Match(pReader, pos, 0x03, i.type))
+            ;
+        else if (Match(pReader, pos, 0x136E, i.nameAsUTF8))
+            assert(i.nameAsUTF8);
+        else if (Match(pReader, pos, 0x06, i.codecId))
+            ;
+        else if (Match(pReader,
+                       pos,
+                       0x23A2,
+                       i.codecPrivate,
+                       i.codecPrivateSize))
+            ;
+        else if (Match(pReader, pos, 0x058688, i.codecNameAsUTF8))
+            assert(i.codecNameAsUTF8);
+        else
+        {
+            long len;
+
+            const long long id = ReadUInt(pReader, pos, len);
+            assert(id >= 0);  //TODO: handle error case
+            assert((pos + len) <= stop);
+
+            pos += len;  //consume id
+
+            const long long size = ReadUInt(pReader, pos, len);
+            assert(size >= 0);  //TODO: handle error case
+            assert((pos + len) <= stop);
+
+            pos += len;  //consume length of size
+            const long long start = pos;
+
+            pos += size;  //consume payload
+            assert(pos <= stop);
+
+            if (id == 0x60)
+            {
+                videoSettings.start = start;
+                videoSettings.size = size;
+            }
+            else if (id == 0x61)
+            {
+                audioSettings.start = start;
+                audioSettings.size = size;
+            }
+        }
+    }
+
+    assert(pos == stop);
+    //TODO: propertly vet info.number, to ensure both its existence,
+    //and that it is unique among all tracks.
+    assert(i.number > 0);
+
+    //TODO: vet settings, to ensure that video settings (0x60)
+    //were specified when type = 1, and that audio settings (0x61)
+    //were specified when type = 2.
+    if (i.type == 1)  //video
+    {
+        assert(audioSettings.start < 0);
+        assert(videoSettings.start >= 0);
+
+        i.settings = videoSettings;
+
+        VideoTrack* const t = new VideoTrack(m_pSegment, i);
+        assert(t);  //TODO
+        pTrack = t;
+    }
+    else if (i.type == 2)  //audio
+    {
+        assert(videoSettings.start < 0);
+        assert(audioSettings.start >= 0);
+
+        i.settings = audioSettings;
+
+        AudioTrack* const t = new  AudioTrack(m_pSegment, i);
+        assert(t);  //TODO
+        pTrack = t;
+    }
+    else
+    {
+        // for now we do not support other track types yet.
+        // TODO: support other track types
+        i.Clear();
+
+        pTrack = NULL;
+    }
+
+    return;
+}
+
+
+Tracks::~Tracks()
+{
+    Track** i = m_trackEntries;
+    Track** const j = m_trackEntriesEnd;
+
+    while (i != j)
+    {
+        Track* const pTrack = *i++;
+        delete pTrack;
+    }
+
+    delete[] m_trackEntries;
+}
+
+
+Track* Tracks::GetTrackByNumber(unsigned long tn_) const
+{
+    const long long tn = tn_;
+
+    Track** i = m_trackEntries;
+    Track** const j = m_trackEntriesEnd;
+
+    while (i != j)
+    {
+        Track* const pTrack = *i++;
+
+        if (pTrack == NULL)
+            continue;
+
+        if (tn == pTrack->GetNumber())
+            return pTrack;
+    }
+
+    return NULL;  //not found
+}
+
+
+Track* Tracks::GetTrackByIndex(unsigned long idx) const
+{
+    const ptrdiff_t count = m_trackEntriesEnd - m_trackEntries;
+
+    if (idx >= static_cast<unsigned long>(count))
+         return NULL;
+
+    return m_trackEntries[idx];
+}
+
+
+void Cluster::Load()
+{
+    assert(m_pSegment);
+    assert(m_pos);
+    assert(m_size);
+
+    if (m_pos > 0)  //loaded
+    {
+        assert(m_size > 0);
+        assert(m_timecode >= 0);
+        return;
+    }
+
+    assert(m_pos < 0);  //not loaded yet
+    assert(m_size < 0);
+    assert(m_timecode < 0);
+
+    IMkvReader* const pReader = m_pSegment->m_pReader;
+
+    m_pos *= -1;                                  //relative to segment
+    long long pos = m_pSegment->m_start + m_pos;  //absolute
+
+    long len;
+
+    const long long id_ = ReadUInt(pReader, pos, len);
+    assert(id_ >= 0);
+    assert(id_ == 0x0F43B675);  //Cluster ID
+
+    pos += len;  //consume id
+
+    const long long size_ = ReadUInt(pReader, pos, len);
+    assert(size_ >= 0);
+
+    pos += len;  //consume size
+
+    m_size = size_;
+    const long long stop = pos + size_;
+
+    long long timecode = -1;
+
+    while (pos < stop)
+    {
+        if (Match(pReader, pos, 0x67, timecode))
+            break;
+        else
+        {
+            const long long id = ReadUInt(pReader, pos, len);
+            assert(id >= 0);  //TODO
+            assert((pos + len) <= stop);
+
+            pos += len;  //consume id
+
+            const long long size = ReadUInt(pReader, pos, len);
+            assert(size >= 0);  //TODO
+            assert((pos + len) <= stop);
+
+            pos += len;  //consume size
+
+            if (id == 0x20)  //BlockGroup ID
+                break;
+
+            if (id == 0x23)  //SimpleBlock ID
+                break;
+
+            pos += size;  //consume payload
+            assert(pos <= stop);
+        }
+    }
+
+    assert(pos <= stop);
+    assert(timecode >= 0);
+
+    m_timecode = timecode;
+}
+
+
+Cluster* Cluster::Parse(
+    Segment* pSegment,
+    long idx,
+    long long off)
+{
+    assert(pSegment);
+    assert(off >= 0);
+    assert(off < pSegment->m_size);
+
+    Cluster* const pCluster = new Cluster(pSegment, idx, -off);
+    assert(pCluster);
+
+    return pCluster;
+}
+
+
+Cluster::Cluster() :
+    m_pSegment(NULL),
+    m_index(0),
+    m_pos(0),
+    m_size(0),
+    m_timecode(0),
+    m_entries(NULL),
+    m_entriesCount(0)
+{
+}
+
+
+Cluster::Cluster(
+    Segment* pSegment,
+    long idx,
+    long long off) :
+    m_pSegment(pSegment),
+    m_index(idx),
+    m_pos(off),
+    m_size(-1),
+    m_timecode(-1),
+    m_entries(NULL),
+    m_entriesCount(0)
+{
+}
+
+
+Cluster::~Cluster()
+{
+    BlockEntry** i = m_entries;
+    BlockEntry** const j = m_entries + m_entriesCount;
+
+    while (i != j)
+    {
+         BlockEntry* p = *i++;
+         assert(p);
+
+         delete p;
+    }
+
+    delete[] m_entries;
+}
+
+
+bool Cluster::EOS() const
+{
+    return (m_pSegment == NULL);
+}
+
+
+void Cluster::LoadBlockEntries()
+{
+    if (m_entries)
+        return;
+
+    assert(m_pSegment);
+    assert(m_pos);
+    assert(m_size);
+    assert(m_entriesCount == 0);
+
+    IMkvReader* const pReader = m_pSegment->m_pReader;
+
+    if (m_pos < 0)
+        m_pos *= -1;  //relative to segment
+
+    long long pos = m_pSegment->m_start + m_pos;  //absolute
+
+    {
+        long len;
+
+        const long long id = ReadUInt(pReader, pos, len);
+        id;
+        assert(id >= 0);
+        assert(id == 0x0F43B675);  //Cluster ID
+
+        pos += len;  //consume id
+
+        const long long size = ReadUInt(pReader, pos, len);
+        assert(size > 0);
+
+        pos += len;  //consume size
+
+        //pos now points to start of payload
+
+        if (m_size >= 0)
+            assert(size == m_size);
+        else
+            m_size = size;
+    }
+
+    const long long stop = pos + m_size;
+    long long timecode = -1;  //of cluster itself
+
+    //First count the number of entries
+
+    long long idx = pos;  //points to start of payload
+    m_entriesCount = 0;
+
+    while (idx < stop)
+    {
+        if (Match(pReader, idx, 0x67, timecode))
+        {
+            if (m_timecode >= 0)
+                assert(timecode == m_timecode);
+            else
+                m_timecode = timecode;
+        }
+        else
+        {
+            long len;
+
+            const long long id = ReadUInt(pReader, idx, len);
+            assert(id >= 0);  //TODO
+            assert((idx + len) <= stop);
+
+            idx += len;  //consume id
+
+            const long long size = ReadUInt(pReader, idx, len);
+            assert(size >= 0);  //TODO
+            assert((idx + len) <= stop);
+
+            idx += len;  //consume size
+
+            if (id == 0x20)  //BlockGroup ID
+                ++m_entriesCount;
+            else if (id == 0x23)  //SimpleBlock ID
+                ++m_entriesCount;
+
+            idx += size;  //consume payload
+            assert(idx <= stop);
+        }
+    }
+
+    assert(idx == stop);
+    assert(m_timecode >= 0);
+
+    if (m_entriesCount == 0)  //TODO: handle empty clusters
+        return;
+
+    m_entries = new BlockEntry*[m_entriesCount];
+    size_t index = 0;
+
+    while (pos < stop)
+    {
+        if (Match(pReader, pos, 0x67, timecode))
+            assert(timecode == m_timecode);
+        else
+        {
+            long len;
+            const long long id = ReadUInt(pReader, pos, len);
+            assert(id >= 0);  //TODO
+            assert((pos + len) <= stop);
+
+            pos += len;  //consume id
+
+            const long long size = ReadUInt(pReader, pos, len);
+            assert(size >= 0);  //TODO
+            assert((pos + len) <= stop);
+
+            pos += len;  //consume size
+
+            if (id == 0x20)  //BlockGroup ID
+                ParseBlockGroup(pos, size, index++);
+            else if (id == 0x23)  //SimpleBlock ID
+                ParseSimpleBlock(pos, size, index++);
+
+            pos += size;  //consume payload
+            assert(pos <= stop);
+        }
+    }
+
+    assert(pos == stop);
+    assert(timecode >= 0);
+    assert(index == m_entriesCount);
+}
+
+
+
+long long Cluster::GetTimeCode()
+{
+    Load();
+    return m_timecode;
+}
+
+
+long long Cluster::GetTime()
+{
+    const long long tc = GetTimeCode();
+    assert(tc >= 0);
+
+    const SegmentInfo* const pInfo = m_pSegment->GetInfo();
+    assert(pInfo);
+
+    const long long scale = pInfo->GetTimeCodeScale();
+    assert(scale >= 1);
+
+    const long long t = m_timecode * scale;
+
+    return t;
+}
+
+
+long long Cluster::GetFirstTime()
+{
+    const BlockEntry* const pEntry = GetFirst();
+
+    if (pEntry == NULL)  //empty cluster
+        return GetTime();
+
+    const Block* const pBlock = pEntry->GetBlock();
+    assert(pBlock);
+
+    return pBlock->GetTime(this);
+}
+
+
+long long Cluster::GetLastTime()
+{
+    const BlockEntry* const pEntry = GetLast();
+
+    if (pEntry == NULL)  //empty cluster
+        return GetTime();
+
+    const Block* const pBlock = pEntry->GetBlock();
+    assert(pBlock);
+
+    return pBlock->GetTime(this);
+}
+
+
+void Cluster::ParseBlockGroup(long long start, long long size, size_t index)
+{
+    assert(m_entries);
+    assert(m_entriesCount);
+    assert(index < m_entriesCount);
+
+    BlockGroup* const pGroup =
+        new (std::nothrow) BlockGroup(this, index, start, size);
+    assert(pGroup);  //TODO
+
+    m_entries[index] = pGroup;
+}
+
+
+
+void Cluster::ParseSimpleBlock(long long start, long long size, size_t index)
+{
+    assert(m_entries);
+    assert(m_entriesCount);
+    assert(index < m_entriesCount);
+
+    SimpleBlock* const pSimpleBlock =
+        new (std::nothrow) SimpleBlock(this, index, start, size);
+    assert(pSimpleBlock);  //TODO
+
+    m_entries[index] = pSimpleBlock;
+}
+
+
+const BlockEntry* Cluster::GetFirst()
+{
+    LoadBlockEntries();
+    //assert(m_entries);
+    //assert(m_entriesCount >= 1);
+
+    if ((m_entries == NULL) || (m_entriesCount == 0))
+        return NULL;
+
+    const BlockEntry* const pFirst = m_entries[0];
+    assert(pFirst);
+
+    return pFirst;
+}
+
+
+const BlockEntry* Cluster::GetLast()
+{
+    LoadBlockEntries();
+    //assert(m_entries);
+    //assert(m_entriesCount >= 1);
+
+    if ((m_entries == NULL) || (m_entriesCount == 0))
+        return NULL;
+
+    const size_t idx = m_entriesCount - 1;
+
+    const BlockEntry* const pLast = m_entries[idx];
+    assert(pLast);
+
+    return pLast;
+}
+
+
+const BlockEntry* Cluster::GetNext(const BlockEntry* pEntry) const
+{
+    assert(pEntry);
+    assert(m_entries);
+    assert(m_entriesCount);
+
+    size_t idx = pEntry->GetIndex();
+    assert(idx < m_entriesCount);
+    assert(m_entries[idx] == pEntry);
+
+    ++idx;
+
+    if (idx >= m_entriesCount)
+      return NULL;
+
+    return m_entries[idx];
+}
+
+
+const BlockEntry* Cluster::GetEntry(const Track* pTrack)
+{
+    assert(pTrack);
+
+    if (m_pSegment == NULL)  //EOS
+        return pTrack->GetEOS();
+
+    LoadBlockEntries();
+
+    if ((m_entries == NULL) || (m_entriesCount == 0))
+        return NULL;
+
+    BlockEntry** i = m_entries;
+    assert(i);
+
+    BlockEntry** const j = i + m_entriesCount;
+
+    while (i != j)
+    {
+        const BlockEntry* const pEntry = *i++;
+        assert(pEntry);
+        assert(!pEntry->EOS());
+
+        const Block* const pBlock = pEntry->GetBlock();
+        assert(pBlock);
+
+        if (pBlock->GetTrackNumber() != pTrack->GetNumber())
+            continue;
+
+        if (pTrack->VetEntry(pEntry))
+            return pEntry;
+    }
+
+    return pTrack->GetEOS();  //no satisfactory block found
+}
+
+
+const BlockEntry*
+Cluster::GetEntry(
+    const CuePoint& cp,
+    const CuePoint::TrackPosition& tp)
+{
+    assert(m_pSegment);
+
+    LoadBlockEntries();
+
+    if (m_entries == NULL)
+        return NULL;
+
+    const long long count = m_entriesCount;
+
+    if (count <= 0)
+        return NULL;
+
+    const long long tc = cp.GetTimeCode();
+
+    if ((tp.m_block > 0) && (tp.m_block <= count))
+    {
+        const size_t block = static_cast<size_t>(tp.m_block);
+        const size_t index = block - 1;
+
+        const BlockEntry* const pEntry = m_entries[index];
+        assert(pEntry);
+        assert(!pEntry->EOS());
+
+        const Block* const pBlock = pEntry->GetBlock();
+        assert(pBlock);
+
+        if ((pBlock->GetTrackNumber() == tp.m_track) &&
+            (pBlock->GetTimeCode(this) == tc))
+        {
+            return pEntry;
+        }
+    }
+
+    const BlockEntry* const* i = m_entries;
+    const BlockEntry* const* const j = i + count;
+
+    while (i != j)
+    {
+        const BlockEntry* const pEntry = *i++;
+        assert(pEntry);
+        assert(!pEntry->EOS());
+
+        const Block* const pBlock = pEntry->GetBlock();
+        assert(pBlock);
+
+        if (pBlock->GetTrackNumber() != tp.m_track)
+            continue;
+
+        const long long tc_ = pBlock->GetTimeCode(this);
+
+        if (tc_ < tc)
+            continue;
+
+        if (tc_ > tc)
+            return NULL;
+
+        const Tracks* const pTracks = m_pSegment->GetTracks();
+        assert(pTracks);
+
+        const long tn = static_cast<long>(tp.m_track);
+        const Track* const pTrack = pTracks->GetTrackByNumber(tn);
+
+        if (pTrack == NULL)
+            return NULL;
+
+        const long long type = pTrack->GetType();
+
+        if (type == 2)  //audio
+            return pEntry;
+
+        if (type != 1)  //not video
+            return NULL;
+
+        if (!pBlock->IsKey())
+            return NULL;
+
+        return pEntry;
+    }
+
+    return NULL;
+}
+
+
+const BlockEntry* Cluster::GetMaxKey(const VideoTrack* pTrack)
+{
+    assert(pTrack);
+
+    if (m_pSegment == NULL)  //EOS
+        return pTrack->GetEOS();
+
+    LoadBlockEntries();
+    //assert(m_entries);
+
+    BlockEntry** i = m_entries + m_entriesCount;
+    BlockEntry** const j = m_entries;
+
+    while (i != j)
+    {
+        const BlockEntry* const pEntry = *--i;
+        assert(pEntry);
+        assert(!pEntry->EOS());
+
+        const Block* const pBlock = pEntry->GetBlock();
+        assert(pBlock);
+
+        if (pBlock->GetTrackNumber() != pTrack->GetNumber())
+            continue;
+
+        if (pBlock->IsKey())
+            return pEntry;
+    }
+
+    return pTrack->GetEOS();  //no satisfactory block found
+}
+
+
+
+BlockEntry::BlockEntry()
+{
+}
+
+
+BlockEntry::~BlockEntry()
+{
+}
+
+
+SimpleBlock::SimpleBlock(
+    Cluster* pCluster,
+    size_t idx,
+    long long start,
+    long long size) :
+    m_pCluster(pCluster),
+    m_index(idx),
+    m_block(start, size, pCluster->m_pSegment->m_pReader)
+{
+}
+
+
+bool SimpleBlock::EOS() const
+{
+    return false;
+}
+
+
+Cluster* SimpleBlock::GetCluster() const
+{
+    return m_pCluster;
+}
+
+
+size_t SimpleBlock::GetIndex() const
+{
+    return m_index;
+}
+
+
+const Block* SimpleBlock::GetBlock() const
+{
+    return &m_block;
+}
+
+
+bool SimpleBlock::IsBFrame() const
+{
+    return false;
+}
+
+
+BlockGroup::BlockGroup(
+    Cluster* pCluster,
+    size_t idx,
+    long long start,
+    long long size_) :
+    m_pCluster(pCluster),
+    m_index(idx),
+    m_prevTimeCode(0),
+    m_nextTimeCode(0),
+    m_pBlock(NULL)  //TODO: accept multiple blocks within a block group
+{
+    IMkvReader* const pReader = m_pCluster->m_pSegment->m_pReader;
+
+    long long pos = start;
+    const long long stop = start + size_;
+
+    bool bSimpleBlock = false;
+    bool bReferenceBlock = false;
+
+    while (pos < stop)
+    {
+        short t;
+
+        if (Match(pReader, pos, 0x7B, t))
+        {
+            if (t < 0)
+                m_prevTimeCode = t;
+            else if (t > 0)
+                m_nextTimeCode = t;
+            else
+                assert(false);
+
+            bReferenceBlock = true;
+        }
+        else
+        {
+            long len;
+            const long long id = ReadUInt(pReader, pos, len);
+            assert(id >= 0);  //TODO
+            assert((pos + len) <= stop);
+
+            pos += len;  //consume ID
+
+            const long long size = ReadUInt(pReader, pos, len);
+            assert(size >= 0);  //TODO
+            assert((pos + len) <= stop);
+
+            pos += len;  //consume size
+
+            switch (id)
+            {
+                case 0x23:  //SimpleBlock ID
+                    bSimpleBlock = true;
+                    //YES, FALL THROUGH TO NEXT CASE
+
+                case 0x21:  //Block ID
+                    ParseBlock(pos, size);
+                    break;
+
+                default:
+                    break;
+            }
+
+            pos += size;  //consume payload
+            assert(pos <= stop);
+        }
+    }
+
+    assert(pos == stop);
+    assert(m_pBlock);
+
+    if (!bSimpleBlock)
+        m_pBlock->SetKey(!bReferenceBlock);
+}
+
+
+BlockGroup::~BlockGroup()
+{
+    delete m_pBlock;
+}
+
+
+void BlockGroup::ParseBlock(long long start, long long size)
+{
+    IMkvReader* const pReader = m_pCluster->m_pSegment->m_pReader;
+
+    Block* const pBlock = new Block(start, size, pReader);
+    assert(pBlock);  //TODO
+
+    //TODO: the Matroska spec says you have multiple blocks within the
+    //same block group, with blocks ranked by priority (the flag bits).
+
+    assert(m_pBlock == NULL);
+    m_pBlock = pBlock;
+}
+
+
+bool BlockGroup::EOS() const
+{
+    return false;
+}
+
+
+Cluster* BlockGroup::GetCluster() const
+{
+    return m_pCluster;
+}
+
+
+size_t BlockGroup::GetIndex() const
+{
+    return m_index;
+}
+
+
+const Block* BlockGroup::GetBlock() const
+{
+    return m_pBlock;
+}
+
+
+short BlockGroup::GetPrevTimeCode() const
+{
+    return m_prevTimeCode;
+}
+
+
+short BlockGroup::GetNextTimeCode() const
+{
+    return m_nextTimeCode;
+}
+
+
+bool BlockGroup::IsBFrame() const
+{
+    return (m_nextTimeCode > 0);
+}
+
+
+
+Block::Block(long long start, long long size_, IMkvReader* pReader) :
+    m_start(start),
+    m_size(size_)
+{
+    long long pos = start;
+    const long long stop = start + size_;
+
+    long len;
+
+    m_track = ReadUInt(pReader, pos, len);
+    assert(m_track > 0);
+    assert((pos + len) <= stop);
+
+    pos += len;  //consume track number
+    assert((stop - pos) >= 2);
+
+    m_timecode = Unserialize2SInt(pReader, pos);
+
+    pos += 2;
+    assert((stop - pos) >= 1);
+
+    const long hr = pReader->Read(pos, 1, &m_flags);
+    assert(hr == 0L);
+
+    ++pos;
+    assert(pos <= stop);
+
+    m_frameOff = pos;
+
+    const long long frame_size = stop - pos;
+
+    assert(frame_size <= 2147483647L);
+
+    m_frameSize = static_cast<long>(frame_size);
+}
+
+
+long long Block::GetTimeCode(Cluster* pCluster) const
+{
+    assert(pCluster);
+
+    const long long tc0 = pCluster->GetTimeCode();
+    assert(tc0 >= 0);
+
+    const long long tc = tc0 + static_cast<long long>(m_timecode);
+    assert(tc >= 0);
+
+    return tc;  //unscaled timecode units
+}
+
+
+long long Block::GetTime(Cluster* pCluster) const
+{
+    assert(pCluster);
+
+    const long long tc = GetTimeCode(pCluster);
+
+    const Segment* const pSegment = pCluster->m_pSegment;
+    const SegmentInfo* const pInfo = pSegment->GetInfo();
+    assert(pInfo);
+
+    const long long scale = pInfo->GetTimeCodeScale();
+    assert(scale >= 1);
+
+    const long long ns = tc * scale;
+
+    return ns;
+}
+
+
+long long Block::GetTrackNumber() const
+{
+    return m_track;
+}
+
+
+bool Block::IsKey() const
+{
+    return ((m_flags & static_cast<unsigned char>(1 << 7)) != 0);
+}
+
+unsigned char Block::Flags() const {
+    return m_flags;
+}
+
+void Block::SetKey(bool bKey)
+{
+    if (bKey)
+        m_flags |= static_cast<unsigned char>(1 << 7);
+    else
+        m_flags &= 0x7F;
+}
+
+
+long long Block::GetOffset() const
+{
+  return m_frameOff;
+}
+
+
+long Block::GetSize() const
+{
+    return m_frameSize;
+}
+
+
+long Block::Read(IMkvReader* pReader, unsigned char* buf) const
+{
+
+    assert(pReader);
+    assert(buf);
+
+    const long hr = pReader->Read(m_frameOff, m_frameSize, buf);
+
+    return hr;
+}
+
+
+}  //end namespace mkvparser
diff --git a/mkvparser/mkvparser.hpp b/mkvparser/mkvparser.hpp
new file mode 100644
index 0000000..f7d8948
--- /dev/null
+++ b/mkvparser/mkvparser.hpp
@@ -0,0 +1,556 @@
+// Copyright (c) 2010 The WebM project authors. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the LICENSE file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS.  All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+
+#ifndef MKVPARSER_HPP
+#define MKVPARSER_HPP
+
+#include <cstdlib>
+#include <cstdio>
+
+namespace mkvparser
+{
+
+const int E_FILE_FORMAT_INVALID = -2;
+const int E_BUFFER_NOT_FULL = -3;
+
+class IMkvReader
+{
+public:
+    virtual int Read(long long pos, long len, unsigned char* buf) = 0;
+    virtual int Length(long long* total, long long* available) = 0;
+protected:
+    virtual ~IMkvReader();
+};
+
+long long GetUIntLength(IMkvReader*, long long, long&);
+long long ReadUInt(IMkvReader*, long long, long&);
+long long SyncReadUInt(IMkvReader*, long long pos, long long stop, long&);
+long long UnserializeUInt(IMkvReader*, long long pos, long long size);
+float Unserialize4Float(IMkvReader*, long long);
+double Unserialize8Double(IMkvReader*, long long);
+short Unserialize2SInt(IMkvReader*, long long);
+signed char Unserialize1SInt(IMkvReader*, long long);
+bool Match(IMkvReader*, long long&, unsigned long, long long&);
+bool Match(IMkvReader*, long long&, unsigned long, char*&);
+bool Match(IMkvReader*, long long&, unsigned long,unsigned char*&, size_t&);
+bool Match(IMkvReader*, long long&, unsigned long, double&);
+bool Match(IMkvReader*, long long&, unsigned long, short&);
+
+void GetVersion(int& major, int& minor, int& build, int& revision);
+
+struct EBMLHeader
+{
+    EBMLHeader();
+    ~EBMLHeader();
+    long long m_version;
+    long long m_readVersion;
+    long long m_maxIdLength;
+    long long m_maxSizeLength;
+    char* m_docType;
+    long long m_docTypeVersion;
+    long long m_docTypeReadVersion;
+
+    long long Parse(IMkvReader*, long long&);
+};
+
+
+class Segment;
+class Track;
+class Cluster;
+
+class Block
+{
+    Block(const Block&);
+    Block& operator=(const Block&);
+
+public:
+    const long long m_start;
+    const long long m_size;
+
+    Block(long long start, long long size, IMkvReader*);
+
+    long long GetTrackNumber() const;
+    long long GetTimeCode(Cluster*) const;  //absolute, but not scaled
+    long long GetTime(Cluster*) const;      //absolute, and scaled (ns units)
+    bool IsKey() const;
+    void SetKey(bool);
+
+    unsigned char Flags() const;
+
+    long long GetOffset() const;
+    long GetSize() const;
+    long Read(IMkvReader*, unsigned char*) const;
+
+private:
+    long long m_track;   //Track::Number()
+    short m_timecode;  //relative to cluster
+    unsigned char m_flags;
+    long long m_frameOff;
+    long m_frameSize;
+
+};
+
+
+class BlockEntry
+{
+    BlockEntry(const BlockEntry&);
+    BlockEntry& operator=(const BlockEntry&);
+
+public:
+    virtual ~BlockEntry();
+    virtual bool EOS() const = 0;
+    virtual Cluster* GetCluster() const = 0;
+    virtual size_t GetIndex() const = 0;
+    virtual const Block* GetBlock() const = 0;
+    virtual bool IsBFrame() const = 0;
+
+protected:
+    BlockEntry();
+
+};
+
+
+class SimpleBlock : public BlockEntry
+{
+    SimpleBlock(const SimpleBlock&);
+    SimpleBlock& operator=(const SimpleBlock&);
+
+public:
+    SimpleBlock(Cluster*, size_t, long long start, long long size);
+
+    bool EOS() const;
+    Cluster* GetCluster() const;
+    size_t GetIndex() const;
+    const Block* GetBlock() const;
+    bool IsBFrame() const;
+
+protected:
+    Cluster* const m_pCluster;
+    const size_t m_index;
+    Block m_block;
+
+};
+
+
+class BlockGroup : public BlockEntry
+{
+    BlockGroup(const BlockGroup&);
+    BlockGroup& operator=(const BlockGroup&);
+
+public:
+    BlockGroup(Cluster*, size_t, long long, long long);
+    ~BlockGroup();
+
+    bool EOS() const;
+    Cluster* GetCluster() const;
+    size_t GetIndex() const;
+    const Block* GetBlock() const;
+    bool IsBFrame() const;
+
+    short GetPrevTimeCode() const;  //relative to block's time
+    short GetNextTimeCode() const;  //as above
+
+protected:
+    Cluster* const m_pCluster;
+    const size_t m_index;
+
+private:
+    BlockGroup(Cluster*, size_t, unsigned long);
+    void ParseBlock(long long start, long long size);
+
+    short m_prevTimeCode;
+    short m_nextTimeCode;
+
+    //TODO: the Matroska spec says you can have multiple blocks within the
+    //same block group, with blocks ranked by priority (the flag bits).
+    //For now we just cache a single block.
+#if 0
+    typedef std::deque<Block*> blocks_t;
+    blocks_t m_blocks;  //In practice should contain only a single element.
+#else
+    Block* m_pBlock;
+#endif
+
+};
+
+
+class Track
+{
+    Track(const Track&);
+    Track& operator=(const Track&);
+
+public:
+    Segment* const m_pSegment;
+    virtual ~Track();
+
+    long long GetType() const;
+    long long GetNumber() const;
+    const char* GetNameAsUTF8() const;
+    const char* GetCodecNameAsUTF8() const;
+    const char* GetCodecId() const;
+    const unsigned char* GetCodecPrivate(size_t&) const;
+
+    const BlockEntry* GetEOS() const;
+
+    struct Settings
+    {
+        long long start;
+        long long size;
+    };
+
+    struct Info
+    {
+        long long type;
+        long long number;
+        long long uid;
+        char* nameAsUTF8;
+        char* codecId;
+        unsigned char* codecPrivate;
+        size_t codecPrivateSize;
+        char* codecNameAsUTF8;
+        Settings settings;
+        Info();
+        void Clear();
+    };
+
+    long GetFirst(const BlockEntry*&) const;
+    long GetNext(const BlockEntry* pCurr, const BlockEntry*& pNext) const;
+    virtual bool VetEntry(const BlockEntry*) const = 0;
+
+protected:
+    Track(Segment*, const Info&);
+    const Info m_info;
+
+    class EOSBlock : public BlockEntry
+    {
+    public:
+        EOSBlock();
+
+        bool EOS() const;
+        Cluster* GetCluster() const;
+        size_t GetIndex() const;
+        const Block* GetBlock() const;
+        bool IsBFrame() const;
+    };
+
+    EOSBlock m_eos;
+
+};
+
+
+class VideoTrack : public Track
+{
+    VideoTrack(const VideoTrack&);
+    VideoTrack& operator=(const VideoTrack&);
+
+public:
+    VideoTrack(Segment*, const Info&);
+    long long GetWidth() const;
+    long long GetHeight() const;
+    double GetFrameRate() const;
+
+    bool VetEntry(const BlockEntry*) const;
+
+private:
+    long long m_width;
+    long long m_height;
+    double m_rate;
+
+};
+
+
+class AudioTrack : public Track
+{
+    AudioTrack(const AudioTrack&);
+    AudioTrack& operator=(const AudioTrack&);
+
+public:
+    AudioTrack(Segment*, const Info&);
+    double GetSamplingRate() const;
+    long long GetChannels() const;
+    long long GetBitDepth() const;
+    bool VetEntry(const BlockEntry*) const;
+
+private:
+    double m_rate;
+    long long m_channels;
+    long long m_bitDepth;
+};
+
+
+class Tracks
+{
+    Tracks(const Tracks&);
+    Tracks& operator=(const Tracks&);
+
+public:
+    Segment* const m_pSegment;
+    const long long m_start;
+    const long long m_size;
+
+    Tracks(Segment*, long long start, long long size);
+    virtual ~Tracks();
+
+    Track* GetTrackByNumber(unsigned long tn) const;
+    Track* GetTrackByIndex(unsigned long idx) const;
+
+private:
+    Track** m_trackEntries;
+    Track** m_trackEntriesEnd;
+
+    void ParseTrackEntry(long long, long long, Track*&);
+
+public:
+    unsigned long GetTracksCount() const;
+};
+
+
+class SegmentInfo
+{
+    SegmentInfo(const SegmentInfo&);
+    SegmentInfo& operator=(const SegmentInfo&);
+
+public:
+    Segment* const m_pSegment;
+    const long long m_start;
+    const long long m_size;
+
+    SegmentInfo(Segment*, long long start, long long size);
+    ~SegmentInfo();
+    long long GetTimeCodeScale() const;
+    long long GetDuration() const;  //scaled
+    const char* GetMuxingAppAsUTF8() const;
+    const char* GetWritingAppAsUTF8() const;
+    const char* GetTitleAsUTF8() const;
+
+private:
+    long long m_timecodeScale;
+    double m_duration;
+    char* m_pMuxingAppAsUTF8;
+    char* m_pWritingAppAsUTF8;
+    char* m_pTitleAsUTF8;
+};
+
+class Cues;
+class CuePoint
+{
+    friend class Cues;
+
+    CuePoint(size_t, long long);
+    ~CuePoint();
+
+    CuePoint(const CuePoint&);
+    CuePoint& operator=(const CuePoint&);
+
+public:
+    void Load(IMkvReader*);
+
+    long long GetTimeCode() const;      //absolute but unscaled
+    long long GetTime(Segment*) const;  //absolute and scaled (ns units)
+
+    struct TrackPosition
+    {
+        long long m_track;
+        long long m_pos;  //of cluster
+        long long m_block;
+        //codec_state  //defaults to 0
+        //reference = clusters containing req'd referenced blocks
+        //  reftime = timecode of the referenced block
+
+        void Parse(IMkvReader*, long long, long long);
+    };
+
+    const TrackPosition* Find(const Track*) const;
+
+private:
+    const size_t m_index;
+    long long m_timecode;
+    TrackPosition* m_track_positions;
+    size_t m_track_positions_count;
+
+};
+
+
+class Cues
+{
+    friend class Segment;
+
+    Cues(Segment*, long long start, long long size);
+    ~Cues();
+
+    Cues(const Cues&);
+    Cues& operator=(const Cues&);
+
+public:
+    Segment* const m_pSegment;
+    const long long m_start;
+    const long long m_size;
+
+    bool Find(  //lower bound of time_ns
+        long long time_ns,
+        const Track*,
+        const CuePoint*&,
+        const CuePoint::TrackPosition*&) const;
+
+#if 0
+    bool FindNext(  //upper_bound of time_ns
+        long long time_ns,
+        const Track*,
+        const CuePoint*&,
+        const CuePoint::TrackPosition*&) const;
+#endif
+
+    const CuePoint* GetFirst() const;
+    const CuePoint* GetLast() const;
+
+    const CuePoint* GetNext(const CuePoint*) const;
+
+    const BlockEntry* GetBlock(
+                        const CuePoint*,
+                        const CuePoint::TrackPosition*) const;
+
+private:
+    void Init() const;
+    bool LoadCuePoint() const;
+    void PreloadCuePoint(size_t&, long long) const;
+
+    mutable CuePoint** m_cue_points;
+    mutable size_t m_count;
+    mutable size_t m_preload_count;
+    mutable long long m_pos;
+
+};
+
+
+class Cluster
+{
+    Cluster(const Cluster&);
+    Cluster& operator=(const Cluster&);
+
+public:
+    Segment* const m_pSegment;
+
+public:
+    static Cluster* Parse(Segment*, long, long long off);
+
+    Cluster();  //EndOfStream
+    ~Cluster();
+
+    bool EOS() const;
+
+    long long GetTimeCode();   //absolute, but not scaled
+    long long GetTime();       //absolute, and scaled (nanosecond units)
+    long long GetFirstTime();  //time (ns) of first (earliest) block
+    long long GetLastTime();   //time (ns) of last (latest) block
+
+    const BlockEntry* GetFirst();
+    const BlockEntry* GetLast();
+    const BlockEntry* GetNext(const BlockEntry*) const;
+    const BlockEntry* GetEntry(const Track*);
+    const BlockEntry* GetEntry(
+        const CuePoint&,
+        const CuePoint::TrackPosition&);
+    const BlockEntry* GetMaxKey(const VideoTrack*);
+
+protected:
+    Cluster(Segment*, long, long long off);
+
+public:
+    //TODO: these should all be private, with public selector functions
+    long m_index;
+    long long m_pos;
+    long long m_size;
+
+private:
+    long long m_timecode;
+    BlockEntry** m_entries;
+    size_t m_entriesCount;
+
+    void Load();
+    void LoadBlockEntries();
+    void ParseBlockGroup(long long, long long, size_t);
+    void ParseSimpleBlock(long long, long long, size_t);
+
+};
+
+
+class Segment
+{
+    friend class Cues;
+
+    Segment(const Segment&);
+    Segment& operator=(const Segment&);
+
+private:
+    Segment(IMkvReader*, long long pos, long long size);
+
+public:
+    IMkvReader* const m_pReader;
+    const long long m_start;  //posn of segment payload
+    const long long m_size;   //size of segment payload
+    Cluster m_eos;  //TODO: make private?
+
+    static long long CreateInstance(IMkvReader*, long long, Segment*&);
+    ~Segment();
+
+    long Load();  //loads headers and all clusters
+
+    //for incremental loading (splitter)
+    long long Unparsed() const;
+    long long ParseHeaders();  //stops when first cluster is found
+    long LoadCluster();        //loads one cluster
+
+#if 0
+    //This pair parses one cluster, but only changes the state of the
+    //segment object when the cluster is actually added to the index.
+    long ParseCluster(Cluster*&, long long& newpos) const;
+    bool AddCluster(Cluster*, long long);
+#endif
+
+    Tracks* GetTracks() const;
+    const SegmentInfo* GetInfo() const;
+    const Cues* GetCues() const;
+
+    long long GetDuration() const;
+
+    unsigned long GetCount() const;
+    Cluster* GetFirst();
+    Cluster* GetLast();
+    Cluster* GetNext(const Cluster*);
+
+    Cluster* FindCluster(long long time_nanoseconds);
+    const BlockEntry* Seek(long long time_nanoseconds, const Track*);
+
+private:
+
+    long long m_pos;  //absolute file posn; what has been consumed so far
+    SegmentInfo* m_pInfo;
+    Tracks* m_pTracks;
+    Cues* m_pCues;
+    Cluster** m_clusters;
+    long m_clusterCount;         //number of entries for which m_index >= 0
+    long m_clusterPreloadCount;  //number of entries for which m_index < 0
+    long m_clusterSize;          //array size
+
+    void AppendCluster(Cluster*);
+    void PreloadCluster(Cluster*, ptrdiff_t);
+
+    void ParseSeekHead(long long pos, long long size);
+    void ParseSeekEntry(long long pos, long long size);
+    void ParseCues(long long);
+
+    const BlockEntry* GetBlock(
+        const CuePoint&,
+        const CuePoint::TrackPosition&);
+
+};
+
+
+}  //end namespace mkvparser
+
+#endif  //MKVPARSER_HPP