Audio specification structure
typedef struct{
int freq;
Uint16 format;
Uint8 channels;
Uint8 silence;
Uint16 samples;
Uint32 size;
void (*callback)(void *userdata, Uint8 *stream, int len);
void *userdata;
} SDL_AudioSpec;
freq
Audio frequency in samples per second
format
Audio data format
channels
Number of channels: 1 mono, 2 stereo
silence
Audio buffer silence value (calculated)
samples
Audio buffer size in samples
size
Audio buffer size in bytes (calculated)
callback(..)
Callback function for filling the audio buffer
userdata
Pointer the user data which is passed to the callback function
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
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_LoadWAV samples is set to 4096.
SDL_OpenAudio, SDL_LoadWAV