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annotate docs/man3/SDL_AudioCVT.3 @ 4159:a1b03ba2fcd0 SDL-1.2
Updated copyright date
| author | Sam Lantinga <slouken@libsdl.org> |
|---|---|
| date | Mon, 08 Dec 2008 00:25:42 +0000 |
| parents | 4e3b250c950e |
| children | 1238da4a7112 |
| rev | line source |
|---|---|
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1 .TH "SDL_AudioCVT" "3" "Tue 11 Sep 2001, 22:58" "SDL" "SDL API Reference" |
| 0 | 2 .SH "NAME" |
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Erik Heckers fixed bug #493
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3 SDL_AudioCVT \- Audio Conversion Structure |
| 0 | 4 .SH "STRUCTURE DEFINITION" |
| 5 .PP | |
| 6 .nf | |
| 7 \f(CWtypedef struct{ | |
| 8 int needed; | |
| 9 Uint16 src_format; | |
| 10 Uint16 dest_format; | |
| 11 double rate_incr; | |
| 12 Uint8 *buf; | |
| 13 int len; | |
| 14 int len_cvt; | |
| 15 int len_mult; | |
| 16 double len_ratio; | |
| 17 void (*filters[10])(struct SDL_AudioCVT *cvt, Uint16 format); | |
| 18 int filter_index; | |
| 19 } SDL_AudioCVT;\fR | |
| 20 .fi | |
| 21 .PP | |
| 22 .SH "STRUCTURE DATA" | |
| 23 .TP 20 | |
| 24 \fBneeded\fR | |
| 25 Set to one if the conversion is possible | |
| 26 .TP 20 | |
| 27 \fBsrc_format\fR | |
| 28 Audio format of the source | |
| 29 .TP 20 | |
| 30 \fBdest_format\fR | |
| 31 Audio format of the destination | |
| 32 .TP 20 | |
| 33 \fBrate_incr\fR | |
| 34 Rate conversion increment | |
| 35 .TP 20 | |
| 36 \fBbuf\fR | |
| 37 Audio buffer | |
| 38 .TP 20 | |
| 39 \fBlen\fR | |
| 40 Length of the original audio buffer in bytes | |
| 41 .TP 20 | |
| 42 \fBlen_cvt\fR | |
| 43 Length of converted audio buffer in bytes (calculated) | |
| 44 .TP 20 | |
| 45 \fBlen_mult\fR | |
| 46 \fBbuf\fR must be \fBlen\fR*\fBlen_mult\fR bytes in size(calculated) | |
| 47 .TP 20 | |
| 48 \fBlen_ratio\fR | |
| 49 Final audio size is \fBlen\fR*\fBlen_ratio\fR | |
| 50 .TP 20 | |
| 51 \fBfilters[10](\&.\&.)\fR | |
| 52 Pointers to functions needed for this conversion | |
| 53 .TP 20 | |
| 54 \fBfilter_index\fR | |
| 55 Current conversion function | |
| 56 .SH "DESCRIPTION" | |
| 57 .PP | |
| 58 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\&. | |
| 59 .PP | |
| 60 Many of the fields in the \fBSDL_AudioCVT\fR structure should be considered private and their function will not be discussed here\&. | |
| 61 .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\&. | |
| 62 .IP "\fBint\fP \fBlen\fR" 10This is the length of the original audio data in bytes\&. | |
| 63 .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\&. | |
| 64 .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\&. | |
| 65 .SH "SEE ALSO" | |
| 66 .PP | |
| 67 \fI\fBSDL_BuildAudioCVT\fP\fR, \fI\fBSDL_ConvertAudio\fP\fR, \fI\fBSDL_AudioSpec\fR\fR | |
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68 ...\" created by instant / docbook-to-man, Tue 11 Sep 2001, 22:58 |