Pointer the user data which is passed to the callback function
DESCRIPTION
The SDL_AudioSpec structure is used to describe the format of some audio data. This structure is used by SDL_OpenAudio and SDL_LoadWAV. While all fields are used by SDL_OpenAudio only freq, format, samples and channels are used by SDL_LoadWAV. We will detail these common members here.
freq
The number of samples sent to the sound device every second. Common values are 11025, 22050 and 44100. The higher the better.
format
Specifies the size and type of each sample element
AUDIO_U8
AUDIO_S8
AUDIO_U16 or AUDIO_U16LSB
AUDIO_S16 or AUDIO_S16LSB
AUDIO_U16MSB
AUDIO_S16MSB
AUDIO_U16SYS
AUDIO_S16SYS
channels
The number of seperate sound channels. 1 is mono (single channel), 2 is stereo (dual channel).
samples
When used with SDL_OpenAudio this refers to the size of the audio buffer in samples. A sample a chunk of audio data of the size specified in format mulitplied by the number of channels. When the SDL_AudioSpec is used with SDL_LoadWAVsamples is set to 4096.