| .TH "SDL_AudioCVT" "3" "Tue 11 Sep 2001, 22:58" "SDL" "SDL API Reference" |
| .SH "NAME" |
| SDL_AudioCVT \- Audio Conversion Structure |
| .SH "STRUCTURE DEFINITION" |
| .PP |
| .nf |
| \f(CWtypedef struct{ |
| int needed; |
| Uint16 src_format; |
| Uint16 dest_format; |
| double rate_incr; |
| Uint8 *buf; |
| int len; |
| int len_cvt; |
| int len_mult; |
| double len_ratio; |
| void (*filters[10])(struct SDL_AudioCVT *cvt, Uint16 format); |
| int filter_index; |
| } SDL_AudioCVT;\fR |
| .fi |
| .PP |
| .SH "STRUCTURE DATA" |
| .TP 20 |
| \fBneeded\fR |
| Set to one if the conversion is possible |
| .TP 20 |
| \fBsrc_format\fR |
| Audio format of the source |
| .TP 20 |
| \fBdest_format\fR |
| Audio format of the destination |
| .TP 20 |
| \fBrate_incr\fR |
| Rate conversion increment |
| .TP 20 |
| \fBbuf\fR |
| Audio buffer |
| .TP 20 |
| \fBlen\fR |
| Length of the original audio buffer in bytes |
| .TP 20 |
| \fBlen_cvt\fR |
| Length of converted audio buffer in bytes (calculated) |
| .TP 20 |
| \fBlen_mult\fR |
| \fBbuf\fR must be \fBlen\fR*\fBlen_mult\fR bytes in size(calculated) |
| .TP 20 |
| \fBlen_ratio\fR |
| Final audio size is \fBlen\fR*\fBlen_ratio\fR |
| .TP 20 |
| \fBfilters[10](\&.\&.)\fR |
| Pointers to functions needed for this conversion |
| .TP 20 |
| \fBfilter_index\fR |
| Current conversion function |
| .SH "DESCRIPTION" |
| .PP |
| The \fBSDL_AudioCVT\fR is used to convert audio data between different formats\&. A \fBSDL_AudioCVT\fR structure is created with the \fI\fBSDL_BuildAudioCVT\fP\fR function, while the actual conversion is done by the \fI\fBSDL_ConvertAudio\fP\fR function\&. |
| .PP |
| Many of the fields in the \fBSDL_AudioCVT\fR structure should be considered private and their function will not be discussed here\&. |
| .IP "\fBUint8 *\fP\fBbuf\fR" 10This points to the audio data that will be used in the conversion\&. It is both the source and the destination, which means the converted audio data overwrites the original data\&. It also means that the converted data may be larger than the original data (if you were converting from 8-bit to 16-bit, for instance), so you must ensure \fBbuf\fR is large enough\&. See below\&. |
| .IP "\fBint\fP \fBlen\fR" 10This is the length of the original audio data in bytes\&. |
| .IP "\fBint\fP \fBlen_mult\fR" 10As explained above, the audio buffer needs to be big enough to store the converted data, which may be bigger than the original audio data\&. The length of \fBbuf\fR should be \fBlen\fR*\fBlen_mult\fR\&. |
| .IP "\fBdouble\fP \fBlen_ratio\fR" 10When you have finished converting your audio data, you need to know how much of your audio buffer is valid\&. \fBlen\fR*\fBlen_ratio\fR is the size of the converted audio data in bytes\&. This is very similar to \fBlen_mult\fR, however when the convert audio data is shorter than the original \fBlen_mult\fR would be 1\&. \fBlen_ratio\fR, on the other hand, would be a fractional number between 0 and 1\&. |
| .SH "SEE ALSO" |
| .PP |
| \fI\fBSDL_BuildAudioCVT\fP\fR, \fI\fBSDL_ConvertAudio\fP\fR, \fI\fBSDL_AudioSpec\fR\fR |
| .\" created by instant / docbook-to-man, Tue 11 Sep 2001, 22:58 |
