SDL_BuildAudioCVT
Use this function to initialize an SDL_AudioCVT structure for conversion.
Contents
Syntax
int SDL_BuildAudioCVT(SDL_AudioCVT* cvt,
SDL_AudioFormat src_format,
Uint8 src_channels,
int src_rate,
SDL_AudioFormat dst_format,
Uint8 dst_channels,
int dst_rate)
Function Parameters
cvt |
an SDL_AudioCVT structure filled in with audio conversion information |
src_format |
the source format of the audio data; for more info see SDL_AudioFormat |
src_channels |
the number of channels in the source |
src_rate |
the frequency (samples-frames-per-second) of the source |
dst_format |
the destination format of the audio data; for more info see SDL_AudioFormat |
dst_channels |
the number of channels in the destination |
dst_rate |
the frequency (samples-frames-per-second) of the destination |
Return Value
Returns 1 if the audio filter is prepared, 0 if no conversion is needed, or a negative error code on failure; call SDL_GetError() for more information.
Code Examples
// Change 1024 stereo sample frames at 48000Hz from float32 to int16.
SDL_AudioCVT cvt;
SDL_BuildAudioCVT(&cvt, AUDIO_F32, 2, 48000, AUDIO_S16, 2, 48000);
SDL_assert(cvt.needed); // obviously, this one is always needed.
cvt.len = 1024 * 2 * 4; // 1024 stereo float32 sample frames.
cvt.buf = (Uint8 *) SDL_malloc(cvt.len * cvt.len_mult);
// read your float32 data into cvt.buf here.
SDL_ConvertAudio(&cvt);
// cvt.buf has cvt.len_cvt bytes of converted data now.
Remarks
Before an SDL_AudioCVT structure can be used to convert audio data it must be initialized with source and destination information.
This function will zero out every field of the SDL_AudioCVT, so it must be called before the application fills in the final buffer information.
Once this function has returned successfully, and reported that a conversion is necessary, the application fills in the rest of the fields in SDL_AudioCVT, now that it knows how large a buffer it needs to allocate, and then can call SDL_ConvertAudio() to complete the conversion.
