int SDL_BuildAudioCVT(SDL_AudioCVT *cvt, Uint16 src_format, Uint8 src_channels, int src_rate, Uint16 dst_format, Uint8 dst_channels, int dst_rate);
Before an SDL_AudioCVT structure can be used to convert audio data it must be initialized with source and destination information.
src_format and dst_format are the source and destination format of the conversion. (For information on audio formats see SDL_AudioSpec). src_channels and dst_channels are the number of channels in the source and destination formats. Finally, src_rate and dst_rate are the frequency or samples-per-second of the source and destination formats. Once again, see SDL_AudioSpec.
Returns -1 if the filter could not be built or 1 if it could.