SDL_AudioSpec

Name

SDL_AudioSpec -- Audio Specification Structure

Structure Definition

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;

Structure Data

freqAudio frequency in samples per second
formatAudio data format
channelsNumber of channels: 1 mono, 2 stereo
silenceAudio buffer silence value (calculated)
samplesAudio buffer size in samples
sizeAudio buffer size in bytes (calculated)
callback(..)Callback function for filling the audio buffer
userdataPointer 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

Unsigned 8-bit samples

AUDIO_S8

Signed 8-bit samples

AUDIO_U16 or AUDIO_U16LSB

Unsigned 16-bit little-endian samples

AUDIO_S16 or AUDIO_S16LSB

Signed 16-bit little-endian samples

AUDIO_U16MSB

Unsigned 16-bit big-endian samples

AUDIO_S16MSB

Signed 16-bit big-endian samples

AUDIO_U16SYS

Either AUDIO_U16LSB or AUDIO_U16MSB depending on you systems endianness

AUDIO_S16SYS

Either AUDIO_S16LSB or AUDIO_S16MSB depending on you systems endianness

channelsThe number of seperate sound channels. 1 is mono (single channel), 2 is stereo (dual channel).
samplesWhen 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.

See Also

SDL_OpenAudio, SDL_LoadWAV