diff docs/man3/SDL_AudioCVT.3 @ 0:74212992fb08

Initial revision
author Sam Lantinga <slouken@lokigames.com>
date Thu, 26 Apr 2001 16:45:43 +0000
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children 55f1f1b3e27d
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+.TH "SDL_AudioCVT" "3" "Mon 12 Mar 2001, 01:02" "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, Mon 12 Mar 2001, 01:02