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>SDL Library Documentation<
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NAME="SDLCONVERTAUDIO"
CLASS="REFNAMEDIV"
NAME="AEN6501"
>SDL_ConvertAudio -- Convert audio
data to a desired audio format.<
/DIV
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>
(SDL_AudioCVT *cvt
);<
/CODE
CLASS="REFSECT1"
NAME="AEN6511"
CLASS="FUNCTION"
> takes one parameter, <
TT
CLASS="PARAMETER"
>, which was previously initilized. Initilizing a <
A
HREF="sdlaudiocvt.html"
CLASS="STRUCTNAME"
> is a two step process. First of all, the structure must be passed to <
A
HREF="sdlbuildaudiocvt.html"
CLASS="FUNCTION"
> along with source and destination format parameters. Secondly, the <
SPAN
CLASS="STRUCTNAME"
CLASS="STRUCTFIELD"
CLASS="STRUCTNAME"
CLASS="STRUCTFIELD"
> fields must be setup. <
SPAN
CLASS="STRUCTNAME"
CLASS="STRUCTFIELD"
> should point to the audio
data and <
SPAN
CLASS="STRUCTNAME"
CLASS="STRUCTFIELD"
> should be set to the length of the audio
data in bytes. Remember, the length of the buffer pointed to by <
TT
CLASS="STRUCTFIELD"
CLASS="STRUCTFIELD"
CLASS="STRUCTFIELD"
CLASS="STRUCTNAME"
>structure is initilized then we can pass it to <
TT
CLASS="FUNCTION"
>, which will convert the audio
data pointer to by <
SPAN
CLASS="STRUCTNAME"
CLASS="STRUCTFIELD"
CLASS="FUNCTION"
CLASS="RETURNVALUE"
> then the conversion was completed successfully, otherwise <
SPAN
CLASS="RETURNVALUE"
>If the conversion completed successfully then the converted audio
data can be read from <
SPAN
CLASS="STRUCTNAME"
CLASS="STRUCTFIELD"
>. The amount of valid, converted, audio
data in the buffer is equal to <
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CLASS="STRUCTFIELD"
CLASS="STRUCTFIELD"
CLASS="STRUCTNAME"
CLASS="REFSECT1"
NAME="AEN6546"
CLASS="PROGRAMLISTING"
>/* 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\n", 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\n", 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!\n");
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 */
.
.
.
.
</PRE
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></A
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>See Also</H2
><P
><A
HREF="sdlbuildaudiocvt.html"
><TT
CLASS="FUNCTION"
>SDL_BuildAudioCVT</TT
></A
>,
<A
HREF="sdlaudiocvt.html"
><TT
CLASS="FUNCTION"
>SDL_AudioCVT</TT
></A
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