diff docs/man3/SDL_ConvertAudio.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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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/docs/man3/SDL_ConvertAudio.3	Thu Apr 26 16:45:43 2001 +0000
@@ -0,0 +1,95 @@
+.TH "SDL_ConvertAudio" "3" "Mon 12 Mar 2001, 01:02" "SDL" "SDL API Reference" 
+.SH "NAME"
+SDL_ConvertAudio\- Convert audio data to a desired audio format\&.
+.SH "SYNOPSIS"
+.PP
+\fB#include "SDL\&.h"
+.sp
+\fBint \fBSDL_ConvertAudio\fP\fR(\fBSDL_AudioCVT *cvt\fR);
+.SH "DESCRIPTION"
+.PP
+\fBSDL_ConvertAudio\fP takes one parameter, \fBcvt\fR, which was previously initilized\&. Initilizing a \fI\fBSDL_AudioCVT\fR\fR is a two step process\&. First of all, the structure must be passed to \fI\fBSDL_BuildAudioCVT\fP\fR along with source and destination format parameters\&. Secondly, the \fBcvt\fR->\fBbuf\fR and \fBcvt\fR->\fBlen\fR fields must be setup\&. \fBcvt\fR->\fBbuf\fR should point to the audio data and \fBcvt\fR->\fBlen\fR should be set to the length of the audio data in bytes\&. Remember, the length of the buffer pointed to by \fBbuf\fR show be \fBlen\fR*\fBlen_mult\fR bytes in length\&.
+.PP
+Once the \fBSDL_AudioCVT\fRstructure is initilized then we can pass it to \fBSDL_ConvertAudio\fP, which will convert the audio data pointer to by \fBcvt\fR->\fBbuf\fR\&. If \fBSDL_ConvertAudio\fP returned \fB0\fR then the conversion was completed successfully, otherwise \fB-1\fR is returned\&.
+.PP
+If the conversion completed successfully then the converted audio data can be read from \fBcvt\fR->\fBbuf\fR\&. The amount of valid, converted, audio data in the buffer is equal to \fBcvt\fR->\fBlen\fR*\fBcvt\fR->\fBlen_ratio\fR\&.
+.SH "EXAMPLES"
+.PP
+.nf
+\f(CW/* Converting some WAV data to hardware format */
+void my_audio_callback(void *userdata, Uint8 *stream, int len);
+
+SDL_AudioSpec *desired, *obtained;
+SDL_AudioSpec wav_spec;
+SDL_AudioCVT  wav_cvt;
+Uint32 wav_len;
+Uint8 *wav_buf;
+int ret;
+
+/* Allocated audio specs */
+desired=(SDL_AudioSpec *)malloc(sizeof(SDL_AudioSpec));
+obtained=(SDL_AudioSpec *)malloc(sizeof(SDL_AudioSpec));
+
+/* Set desired format */
+desired->freq=22050;
+desired->format=AUDIO_S16LSB;
+desired->samples=8192;
+desired->callback=my_audio_callback;
+desired->userdata=NULL;
+
+/* Open the audio device */
+if ( SDL_OpenAudio(desired, obtained) < 0 ){
+  fprintf(stderr, "Couldn\&'t open audio: %s
+", SDL_GetError());
+  exit(-1);
+}
+        
+free(desired);
+
+/* Load the test\&.wav */
+if( SDL_LoadWAV("test\&.wav", &wav_spec, &wav_buf, &wav_len) == NULL ){
+  fprintf(stderr, "Could not open test\&.wav: %s
+", SDL_GetError());
+  SDL_CloseAudio();
+  free(obtained);
+  exit(-1);
+}
+                                            
+/* Build AudioCVT */
+ret = SDL_BuildAudioCVT(&wav_cvt,
+                        wav_spec\&.format, wav_spec\&.channels, wav_spec\&.freq,
+                        obtained->format, obtained->channels, obtained->freq);
+
+/* Check that the convert was built */
+if(ret==-1){
+  fprintf(stderr, "Couldn\&'t build converter!
+");
+  SDL_CloseAudio();
+  free(obtained);
+  SDL_FreeWAV(wav_buf);
+}
+
+/* Setup for conversion */
+wav_cvt\&.buf=(Uint8 *)malloc(wav_len*wav_cvt\&.len_mult);
+wav_cvt\&.len=wav_len;
+memcpy(wav_cvt\&.buf, wav_buf, wav_len);
+
+/* We can delete to original WAV data now */
+SDL_FreeWAV(wav_buf);
+
+/* And now we\&'re ready to convert */
+SDL_ConvertAudio(&wav_cvt);
+
+/* do whatever */
+\&.
+\&.
+\&.
+\&.
+
+\fR
+.fi
+.PP
+.SH "SEE ALSO"
+.PP
+\fI\fBSDL_BuildAudioCVT\fP\fR, \fI\fBSDL_AudioCVT\fP\fR
+...\" created by instant / docbook-to-man, Mon 12 Mar 2001, 01:02