The calculated values in this structure are calculated by SDL_OpenAudio().
Defined in SDL_audio.h
typedef struct SDL_AudioSpec
{
int freq; /**< DSP frequency -- samples per second */
SDL_AudioFormat format; /**< Audio data format */
Uint8 channels; /**< Number of channels: 1 mono, 2 stereo */
Uint8 silence; /**< Audio buffer silence value (calculated) */
Uint16 samples; /**< Audio buffer size in sample FRAMES (total samples divided by channel count) */
Uint16 padding; /**< Necessary for some compile environments */
Uint32 size; /**< Audio buffer size in bytes (calculated) */
SDL_AudioCallback callback; /**< Callback that feeds the audio device (NULL to use SDL_QueueAudio()). */
void *userdata; /**< Userdata passed to callback (ignored for NULL callbacks). */
} SDL_AudioSpec;For multi-channel audio, the default SDL channel mapping is:
2: FL FR (stereo)
3: FL FR LFE (2.1 surround)
4: FL FR BL BR (quad)
5: FL FR LFE BL BR (4.1 surround)
6: FL FR FC LFE SL SR (5.1 surround - last two can also be BL BR)
7: FL FR FC LFE BC SL SR (6.1 surround)
8: FL FR FC LFE BL BR SL SR (7.1 surround)
SDL_AudioSpec want, have;
SDL_AudioDeviceID dev;
extern void SDLCALL MyAudioCallback(void *userdata, Uint8 *stream, int len);
SDL_memset(&want, 0, sizeof(want)); /* or SDL_zero(want) */
want.freq = 48000;
want.format = AUDIO_F32;
want.channels = 2;
want.samples = 4096;
want.callback = MyAudioCallback; // you wrote this function elsewhere.
dev = SDL_OpenAudioDevice(NULL, 0, &want, &have, SDL_AUDIO_ALLOW_FORMAT_CHANGE);