services/camera/libcameraservice/camera2/JpegProcessor.cpp - platform/frameworks/av - Git at Google

 /*
  * Copyright (C) 2012 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #define LOG_TAG "Camera2-JpegProcessor"
 #define ATRACE_TAG ATRACE_TAG_CAMERA
 //#define LOG_NDEBUG 0

 #include <netinet/in.h>

 #include <binder/MemoryBase.h>
 #include <binder/MemoryHeapBase.h>
 #include <utils/Log.h>
 #include <utils/Trace.h>

 #include "JpegProcessor.h"
 #include <gui/Surface.h>
 #include "../CameraDeviceBase.h"
 #include "../Camera2Client.h"


 namespace android {
 namespace camera2 {

 JpegProcessor::JpegProcessor(
     sp<Camera2Client> client,
     wp<CaptureSequencer> sequencer):
         Thread(false),
         mDevice(client->getCameraDevice()),
         mSequencer(sequencer),
         mId(client->getCameraId()),
         mCaptureAvailable(false),
         mCaptureStreamId(NO_STREAM) {
 }

 JpegProcessor::~JpegProcessor() {
     ALOGV("%s: Exit", __FUNCTION__);
     deleteStream();
 }

 void JpegProcessor::onFrameAvailable() {
     Mutex::Autolock l(mInputMutex);
     if (!mCaptureAvailable) {
         mCaptureAvailable = true;
         mCaptureAvailableSignal.signal();
     }
 }

 status_t JpegProcessor::updateStream(const Parameters &params) {
     ATRACE_CALL();
     ALOGV("%s", __FUNCTION__);
     status_t res;

     Mutex::Autolock l(mInputMutex);

     sp<CameraDeviceBase> device = mDevice.promote();
     if (device == 0) {
         ALOGE("%s: Camera %d: Device does not exist", __FUNCTION__, mId);
         return INVALID_OPERATION;
     }

     // Find out buffer size for JPEG
     camera_metadata_ro_entry_t maxJpegSize =
             params.staticInfo(ANDROID_JPEG_MAX_SIZE);
     if (maxJpegSize.count == 0) {
         ALOGE("%s: Camera %d: Can't find ANDROID_JPEG_MAX_SIZE!",
                 __FUNCTION__, mId);
         return INVALID_OPERATION;
     }

     if (mCaptureConsumer == 0) {
         // Create CPU buffer queue endpoint
         mCaptureConsumer = new CpuConsumer(1);
         mCaptureConsumer->setFrameAvailableListener(this);
         mCaptureConsumer->setName(String8("Camera2Client::CaptureConsumer"));
         mCaptureWindow = new Surface(
             mCaptureConsumer->getProducerInterface());
         // Create memory for API consumption
         mCaptureHeap = new MemoryHeapBase(maxJpegSize.data.i32[0], 0,
                                        "Camera2Client::CaptureHeap");
         if (mCaptureHeap->getSize() == 0) {
             ALOGE("%s: Camera %d: Unable to allocate memory for capture",
                     __FUNCTION__, mId);
             return NO_MEMORY;
         }
     }

     if (mCaptureStreamId != NO_STREAM) {
         // Check if stream parameters have to change
         uint32_t currentWidth, currentHeight;
         res = device->getStreamInfo(mCaptureStreamId,
                 &currentWidth, &currentHeight, 0);
         if (res != OK) {
             ALOGE("%s: Camera %d: Error querying capture output stream info: "
                     "%s (%d)", __FUNCTION__,
                     mId, strerror(-res), res);
             return res;
         }
         if (currentWidth != (uint32_t)params.pictureWidth ||
                 currentHeight != (uint32_t)params.pictureHeight) {
             ALOGV("%s: Camera %d: Deleting stream %d since the buffer dimensions changed",
                 __FUNCTION__, mId, mCaptureStreamId);
             res = device->deleteStream(mCaptureStreamId);
             if (res != OK) {
                 ALOGE("%s: Camera %d: Unable to delete old output stream "
                         "for capture: %s (%d)", __FUNCTION__,
                         mId, strerror(-res), res);
                 return res;
             }
             mCaptureStreamId = NO_STREAM;
         }
     }

     if (mCaptureStreamId == NO_STREAM) {
         // Create stream for HAL production
         res = device->createStream(mCaptureWindow,
                 params.pictureWidth, params.pictureHeight,
                 HAL_PIXEL_FORMAT_BLOB, maxJpegSize.data.i32[0],
                 &mCaptureStreamId);
         if (res != OK) {
             ALOGE("%s: Camera %d: Can't create output stream for capture: "
                     "%s (%d)", __FUNCTION__, mId,
                     strerror(-res), res);
             return res;
         }

     }
     return OK;
 }

 status_t JpegProcessor::deleteStream() {
     ATRACE_CALL();

     Mutex::Autolock l(mInputMutex);

     if (mCaptureStreamId != NO_STREAM) {
         sp<CameraDeviceBase> device = mDevice.promote();
         if (device == 0) {
             ALOGE("%s: Camera %d: Device does not exist", __FUNCTION__, mId);
             return INVALID_OPERATION;
         }

         device->deleteStream(mCaptureStreamId);

         mCaptureHeap.clear();
         mCaptureWindow.clear();
         mCaptureConsumer.clear();

         mCaptureStreamId = NO_STREAM;
     }
     return OK;
 }

 int JpegProcessor::getStreamId() const {
     Mutex::Autolock l(mInputMutex);
     return mCaptureStreamId;
 }

 void JpegProcessor::dump(int /*fd*/, const Vector<String16>& /*args*/) const {
 }

 bool JpegProcessor::threadLoop() {
     status_t res;

     {
         Mutex::Autolock l(mInputMutex);
         while (!mCaptureAvailable) {
             res = mCaptureAvailableSignal.waitRelative(mInputMutex,
                     kWaitDuration);
             if (res == TIMED_OUT) return true;
         }
         mCaptureAvailable = false;
     }

     do {
         res = processNewCapture();
     } while (res == OK);

     return true;
 }

 status_t JpegProcessor::processNewCapture() {
     ATRACE_CALL();
     status_t res;
     sp<Camera2Heap> captureHeap;

     CpuConsumer::LockedBuffer imgBuffer;

     res = mCaptureConsumer->lockNextBuffer(&imgBuffer);
     if (res != OK) {
         if (res != BAD_VALUE) {
             ALOGE("%s: Camera %d: Error receiving still image buffer: "
                     "%s (%d)", __FUNCTION__,
                     mId, strerror(-res), res);
         }
         return res;
     }

     ALOGV("%s: Camera %d: Still capture available", __FUNCTION__,
             mId);

     if (imgBuffer.format != HAL_PIXEL_FORMAT_BLOB) {
         ALOGE("%s: Camera %d: Unexpected format for still image: "
                 "%x, expected %x", __FUNCTION__, mId,
                 imgBuffer.format,
                 HAL_PIXEL_FORMAT_BLOB);
         mCaptureConsumer->unlockBuffer(imgBuffer);
         return OK;
     }

     // Find size of JPEG image
     size_t jpegSize = findJpegSize(imgBuffer.data, imgBuffer.width);
     if (jpegSize == 0) { // failed to find size, default to whole buffer
         jpegSize = imgBuffer.width;
     }
     size_t heapSize = mCaptureHeap->getSize();
     if (jpegSize > heapSize) {
         ALOGW("%s: JPEG image is larger than expected, truncating "
                 "(got %d, expected at most %d bytes)",
                 __FUNCTION__, jpegSize, heapSize);
         jpegSize = heapSize;
     }

     // TODO: Optimize this to avoid memcopy
     sp<MemoryBase> captureBuffer = new MemoryBase(mCaptureHeap, 0, jpegSize);
     void* captureMemory = mCaptureHeap->getBase();
     memcpy(captureMemory, imgBuffer.data, jpegSize);

     mCaptureConsumer->unlockBuffer(imgBuffer);

     sp<CaptureSequencer> sequencer = mSequencer.promote();
     if (sequencer != 0) {
         sequencer->onCaptureAvailable(imgBuffer.timestamp, captureBuffer);
     }

     return OK;
 }

 /*
  * JPEG FILE FORMAT OVERVIEW.
  * http://www.jpeg.org/public/jfif.pdf
  * (JPEG is the image compression algorithm, actual file format is called JFIF)
  *
  * "Markers" are 2-byte patterns used to distinguish parts of JFIF files.  The
  * first byte is always 0xFF, and the second byte is between 0x01 and 0xFE
  * (inclusive).  Because every marker begins with the same byte, they are
  * referred to by the second byte's value.
  *
  * JFIF files all begin with the Start of Image (SOI) marker, which is 0xD8.
  * Following it, "segment" sections begin with other markers, followed by a
  * 2-byte length (in network byte order), then the segment data.
  *
  * For our purposes we will ignore the data, and just use the length to skip to
  * the next segment.  This is necessary because the data inside segments are
  * allowed to contain the End of Image marker (0xFF 0xD9), preventing us from
  * naievely scanning until the end.
  *
  * After all the segments are processed, the jpeg compressed image stream begins.
  * This can be considered an opaque format with one requirement: all 0xFF bytes
  * in this stream must be followed with a 0x00 byte.  This prevents any of the
  * image data to be interpreted as a segment.  The only exception to this is at
  * the end of the image stream there is an End of Image (EOI) marker, which is
  * 0xFF followed by a non-zero (0xD9) byte.
  */

 const uint8_t MARK = 0xFF; // First byte of marker
 const uint8_t SOI = 0xD8; // Start of Image
 const uint8_t EOI = 0xD9; // End of Image
 const size_t MARKER_LENGTH = 2; // length of a marker

 #pragma pack(push)
 #pragma pack(1)
 typedef struct segment {
     uint8_t marker[MARKER_LENGTH];
     uint16_t length;
 } segment_t;
 #pragma pack(pop)

 /* HELPER FUNCTIONS */

 // check for Start of Image marker
 bool checkJpegStart(uint8_t* buf) {
     return buf[0] == MARK && buf[1] == SOI;
 }
 // check for End of Image marker
 bool checkJpegEnd(uint8_t *buf) {
     return buf[0] == MARK && buf[1] == EOI;
 }
 // check for arbitrary marker, returns marker type (second byte)
 // returns 0 if no marker found. Note: 0x00 is not a valid marker type
 uint8_t checkJpegMarker(uint8_t *buf) {
     if (buf[0] == MARK && buf[1] > 0 && buf[1] < 0xFF) {
         return buf[1];
     }
     return 0;
 }

 // Return the size of the JPEG, 0 indicates failure
 size_t JpegProcessor::findJpegSize(uint8_t* jpegBuffer, size_t maxSize) {
     size_t size;

     // First check for JPEG transport header at the end of the buffer
     uint8_t *header = jpegBuffer + (maxSize - sizeof(struct camera2_jpeg_blob));
     struct camera2_jpeg_blob *blob = (struct camera2_jpeg_blob*)(header);
     if (blob->jpeg_blob_id == CAMERA2_JPEG_BLOB_ID) {
         size = blob->jpeg_size;
         if (size > 0 && size <= maxSize - sizeof(struct camera2_jpeg_blob)) {
             // Verify SOI and EOI markers
             size_t offset = size - MARKER_LENGTH;
             uint8_t *end = jpegBuffer + offset;
             if (checkJpegStart(jpegBuffer) && checkJpegEnd(end)) {
                 ALOGV("Found JPEG transport header, img size %d", size);
                 return size;
             } else {
                 ALOGW("Found JPEG transport header with bad Image Start/End");
             }
         } else {
             ALOGW("Found JPEG transport header with bad size %d", size);
         }
     }

     // Check Start of Image
     if ( !checkJpegStart(jpegBuffer) ) {
         ALOGE("Could not find start of JPEG marker");
         return 0;
     }

     // Read JFIF segment markers, skip over segment data
     size = 0;
     while (size <= maxSize - MARKER_LENGTH) {
         segment_t *segment = (segment_t*)(jpegBuffer + size);
         uint8_t type = checkJpegMarker(segment->marker);
         if (type == 0) { // invalid marker, no more segments, begin JPEG data
             ALOGV("JPEG stream found beginning at offset %d", size);
             break;
         }
         if (type == EOI || size > maxSize - sizeof(segment_t)) {
             ALOGE("Got premature End before JPEG data, offset %d", size);
             return 0;
         }
         size_t length = ntohs(segment->length);
         ALOGV("JFIF Segment, type %x length %x", type, length);
         size += length + MARKER_LENGTH;
     }

     // Find End of Image
     // Scan JPEG buffer until End of Image (EOI)
     bool foundEnd = false;
     for ( ; size <= maxSize - MARKER_LENGTH; size++) {
         if ( checkJpegEnd(jpegBuffer + size) ) {
             foundEnd = true;
             size += MARKER_LENGTH;
             break;
         }
     }
     if (!foundEnd) {
         ALOGE("Could not find end of JPEG marker");
         return 0;
     }

     if (size > maxSize) {
         ALOGW("JPEG size %d too large, reducing to maxSize %d", size, maxSize);
         size = maxSize;
     }
     ALOGV("Final JPEG size %d", size);
     return size;
 }

 }; // namespace camera2
 }; // namespace android
	/*
	* Copyright (C) 2012 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#define LOG_TAG "Camera2-JpegProcessor"
	#define ATRACE_TAG ATRACE_TAG_CAMERA
	//#define LOG_NDEBUG 0

	#include <netinet/in.h>

	#include <binder/MemoryBase.h>
	#include <binder/MemoryHeapBase.h>
	#include <utils/Log.h>
	#include <utils/Trace.h>

	#include "JpegProcessor.h"
	#include <gui/Surface.h>
	#include "../CameraDeviceBase.h"
	#include "../Camera2Client.h"


	namespace android {
	namespace camera2 {

	JpegProcessor::JpegProcessor(
	sp<Camera2Client> client,
	wp<CaptureSequencer> sequencer):
	Thread(false),
	mDevice(client->getCameraDevice()),
	mSequencer(sequencer),
	mId(client->getCameraId()),
	mCaptureAvailable(false),
	mCaptureStreamId(NO_STREAM) {
	}

	JpegProcessor::~JpegProcessor() {
	ALOGV("%s: Exit", __FUNCTION__);
	deleteStream();
	}

	void JpegProcessor::onFrameAvailable() {
	Mutex::Autolock l(mInputMutex);
	if (!mCaptureAvailable) {
	mCaptureAvailable = true;
	mCaptureAvailableSignal.signal();
	}
	}

	status_t JpegProcessor::updateStream(const Parameters &params) {
	ATRACE_CALL();
	ALOGV("%s", __FUNCTION__);
	status_t res;

	Mutex::Autolock l(mInputMutex);

	sp<CameraDeviceBase> device = mDevice.promote();
	if (device == 0) {
	ALOGE("%s: Camera %d: Device does not exist", __FUNCTION__, mId);
	return INVALID_OPERATION;
	}

	// Find out buffer size for JPEG
	camera_metadata_ro_entry_t maxJpegSize =
	params.staticInfo(ANDROID_JPEG_MAX_SIZE);
	if (maxJpegSize.count == 0) {
	ALOGE("%s: Camera %d: Can't find ANDROID_JPEG_MAX_SIZE!",
	__FUNCTION__, mId);
	return INVALID_OPERATION;
	}

	if (mCaptureConsumer == 0) {
	// Create CPU buffer queue endpoint
	mCaptureConsumer = new CpuConsumer(1);
	mCaptureConsumer->setFrameAvailableListener(this);
	mCaptureConsumer->setName(String8("Camera2Client::CaptureConsumer"));
	mCaptureWindow = new Surface(
	mCaptureConsumer->getProducerInterface());
	// Create memory for API consumption
	mCaptureHeap = new MemoryHeapBase(maxJpegSize.data.i32[0], 0,
	"Camera2Client::CaptureHeap");
	if (mCaptureHeap->getSize() == 0) {
	ALOGE("%s: Camera %d: Unable to allocate memory for capture",
	__FUNCTION__, mId);
	return NO_MEMORY;
	}
	}

	if (mCaptureStreamId != NO_STREAM) {
	// Check if stream parameters have to change
	uint32_t currentWidth, currentHeight;
	res = device->getStreamInfo(mCaptureStreamId,
	&currentWidth, &currentHeight, 0);
	if (res != OK) {
	ALOGE("%s: Camera %d: Error querying capture output stream info: "
	"%s (%d)", __FUNCTION__,
	mId, strerror(-res), res);
	return res;
	}
	if (currentWidth != (uint32_t)params.pictureWidth \|\|
	currentHeight != (uint32_t)params.pictureHeight) {
	ALOGV("%s: Camera %d: Deleting stream %d since the buffer dimensions changed",
	__FUNCTION__, mId, mCaptureStreamId);
	res = device->deleteStream(mCaptureStreamId);
	if (res != OK) {
	ALOGE("%s: Camera %d: Unable to delete old output stream "
	"for capture: %s (%d)", __FUNCTION__,
	mId, strerror(-res), res);
	return res;
	}
	mCaptureStreamId = NO_STREAM;
	}
	}

	if (mCaptureStreamId == NO_STREAM) {
	// Create stream for HAL production
	res = device->createStream(mCaptureWindow,
	params.pictureWidth, params.pictureHeight,
	HAL_PIXEL_FORMAT_BLOB, maxJpegSize.data.i32[0],
	&mCaptureStreamId);
	if (res != OK) {
	ALOGE("%s: Camera %d: Can't create output stream for capture: "
	"%s (%d)", __FUNCTION__, mId,
	strerror(-res), res);
	return res;
	}

	}
	return OK;
	}

	status_t JpegProcessor::deleteStream() {
	ATRACE_CALL();

	Mutex::Autolock l(mInputMutex);

	if (mCaptureStreamId != NO_STREAM) {
	sp<CameraDeviceBase> device = mDevice.promote();
	if (device == 0) {
	ALOGE("%s: Camera %d: Device does not exist", __FUNCTION__, mId);
	return INVALID_OPERATION;
	}

	device->deleteStream(mCaptureStreamId);

	mCaptureHeap.clear();
	mCaptureWindow.clear();
	mCaptureConsumer.clear();

	mCaptureStreamId = NO_STREAM;
	}
	return OK;
	}

	int JpegProcessor::getStreamId() const {
	Mutex::Autolock l(mInputMutex);
	return mCaptureStreamId;
	}

	void JpegProcessor::dump(int /fd/, const Vector<String16>& /args/) const {
	}

	bool JpegProcessor::threadLoop() {
	status_t res;

	{
	Mutex::Autolock l(mInputMutex);
	while (!mCaptureAvailable) {
	res = mCaptureAvailableSignal.waitRelative(mInputMutex,
	kWaitDuration);
	if (res == TIMED_OUT) return true;
	}
	mCaptureAvailable = false;
	}

	do {
	res = processNewCapture();
	} while (res == OK);

	return true;
	}

	status_t JpegProcessor::processNewCapture() {
	ATRACE_CALL();
	status_t res;
	sp<Camera2Heap> captureHeap;

	CpuConsumer::LockedBuffer imgBuffer;

	res = mCaptureConsumer->lockNextBuffer(&imgBuffer);
	if (res != OK) {
	if (res != BAD_VALUE) {
	ALOGE("%s: Camera %d: Error receiving still image buffer: "
	"%s (%d)", __FUNCTION__,
	mId, strerror(-res), res);
	}
	return res;
	}

	ALOGV("%s: Camera %d: Still capture available", __FUNCTION__,
	mId);

	if (imgBuffer.format != HAL_PIXEL_FORMAT_BLOB) {
	ALOGE("%s: Camera %d: Unexpected format for still image: "
	"%x, expected %x", __FUNCTION__, mId,
	imgBuffer.format,
	HAL_PIXEL_FORMAT_BLOB);
	mCaptureConsumer->unlockBuffer(imgBuffer);
	return OK;
	}

	// Find size of JPEG image
	size_t jpegSize = findJpegSize(imgBuffer.data, imgBuffer.width);
	if (jpegSize == 0) { // failed to find size, default to whole buffer
	jpegSize = imgBuffer.width;
	}
	size_t heapSize = mCaptureHeap->getSize();
	if (jpegSize > heapSize) {
	ALOGW("%s: JPEG image is larger than expected, truncating "
	"(got %d, expected at most %d bytes)",
	__FUNCTION__, jpegSize, heapSize);
	jpegSize = heapSize;
	}

	// TODO: Optimize this to avoid memcopy
	sp<MemoryBase> captureBuffer = new MemoryBase(mCaptureHeap, 0, jpegSize);
	void* captureMemory = mCaptureHeap->getBase();
	memcpy(captureMemory, imgBuffer.data, jpegSize);

	mCaptureConsumer->unlockBuffer(imgBuffer);

	sp<CaptureSequencer> sequencer = mSequencer.promote();
	if (sequencer != 0) {
	sequencer->onCaptureAvailable(imgBuffer.timestamp, captureBuffer);
	}

	return OK;
	}

	/*
	* JPEG FILE FORMAT OVERVIEW.
	* http://www.jpeg.org/public/jfif.pdf
	* (JPEG is the image compression algorithm, actual file format is called JFIF)
	*
	* "Markers" are 2-byte patterns used to distinguish parts of JFIF files. The
	* first byte is always 0xFF, and the second byte is between 0x01 and 0xFE
	* (inclusive). Because every marker begins with the same byte, they are
	* referred to by the second byte's value.
	*
	* JFIF files all begin with the Start of Image (SOI) marker, which is 0xD8.
	* Following it, "segment" sections begin with other markers, followed by a
	* 2-byte length (in network byte order), then the segment data.
	*
	* For our purposes we will ignore the data, and just use the length to skip to
	* the next segment. This is necessary because the data inside segments are
	* allowed to contain the End of Image marker (0xFF 0xD9), preventing us from
	* naievely scanning until the end.
	*
	* After all the segments are processed, the jpeg compressed image stream begins.
	* This can be considered an opaque format with one requirement: all 0xFF bytes
	* in this stream must be followed with a 0x00 byte. This prevents any of the
	* image data to be interpreted as a segment. The only exception to this is at
	* the end of the image stream there is an End of Image (EOI) marker, which is
	* 0xFF followed by a non-zero (0xD9) byte.
	*/

	const uint8_t MARK = 0xFF; // First byte of marker
	const uint8_t SOI = 0xD8; // Start of Image
	const uint8_t EOI = 0xD9; // End of Image
	const size_t MARKER_LENGTH = 2; // length of a marker

	#pragma pack(push)
	#pragma pack(1)
	typedef struct segment {
	uint8_t marker[MARKER_LENGTH];
	uint16_t length;
	} segment_t;
	#pragma pack(pop)

	/* HELPER FUNCTIONS */

	// check for Start of Image marker
	bool checkJpegStart(uint8_t* buf) {
	return buf[0] == MARK && buf[1] == SOI;
	}
	// check for End of Image marker
	bool checkJpegEnd(uint8_t *buf) {
	return buf[0] == MARK && buf[1] == EOI;
	}
	// check for arbitrary marker, returns marker type (second byte)
	// returns 0 if no marker found. Note: 0x00 is not a valid marker type
	uint8_t checkJpegMarker(uint8_t *buf) {
	if (buf[0] == MARK && buf[1] > 0 && buf[1] < 0xFF) {
	return buf[1];
	}
	return 0;
	}

	// Return the size of the JPEG, 0 indicates failure
	size_t JpegProcessor::findJpegSize(uint8_t* jpegBuffer, size_t maxSize) {
	size_t size;

	// First check for JPEG transport header at the end of the buffer
	uint8_t *header = jpegBuffer + (maxSize - sizeof(struct camera2_jpeg_blob));
	struct camera2_jpeg_blob blob = (struct camera2_jpeg_blob)(header);
	if (blob->jpeg_blob_id == CAMERA2_JPEG_BLOB_ID) {
	size = blob->jpeg_size;
	if (size > 0 && size <= maxSize - sizeof(struct camera2_jpeg_blob)) {
	// Verify SOI and EOI markers
	size_t offset = size - MARKER_LENGTH;
	uint8_t *end = jpegBuffer + offset;
	if (checkJpegStart(jpegBuffer) && checkJpegEnd(end)) {
	ALOGV("Found JPEG transport header, img size %d", size);
	return size;
	} else {
	ALOGW("Found JPEG transport header with bad Image Start/End");
	}
	} else {
	ALOGW("Found JPEG transport header with bad size %d", size);
	}
	}

	// Check Start of Image
	if ( !checkJpegStart(jpegBuffer) ) {
	ALOGE("Could not find start of JPEG marker");
	return 0;
	}

	// Read JFIF segment markers, skip over segment data
	size = 0;
	while (size <= maxSize - MARKER_LENGTH) {
	segment_t segment = (segment_t)(jpegBuffer + size);
	uint8_t type = checkJpegMarker(segment->marker);
	if (type == 0) { // invalid marker, no more segments, begin JPEG data
	ALOGV("JPEG stream found beginning at offset %d", size);
	break;
	}
	if (type == EOI \|\| size > maxSize - sizeof(segment_t)) {
	ALOGE("Got premature End before JPEG data, offset %d", size);
	return 0;
	}
	size_t length = ntohs(segment->length);
	ALOGV("JFIF Segment, type %x length %x", type, length);
	size += length + MARKER_LENGTH;
	}

	// Find End of Image
	// Scan JPEG buffer until End of Image (EOI)
	bool foundEnd = false;
	for ( ; size <= maxSize - MARKER_LENGTH; size++) {
	if ( checkJpegEnd(jpegBuffer + size) ) {
	foundEnd = true;
	size += MARKER_LENGTH;
	break;
	}
	}
	if (!foundEnd) {
	ALOGE("Could not find end of JPEG marker");
	return 0;
	}

	if (size > maxSize) {
	ALOGW("JPEG size %d too large, reducing to maxSize %d", size, maxSize);
	size = maxSize;
	}
	ALOGV("Final JPEG size %d", size);
	return size;
	}

	}; // namespace camera2
	}; // namespace android