ALSA's idea of a "frame" is the same as SDL's idea of a "sample". The frame is a single sample on a single channel, and we've defined the frames for each channel as being interleaved.
--- a/src/audio/alsa/SDL_alsa_audio.c Tue Oct 13 09:24:05 2009 +0000
+++ b/src/audio/alsa/SDL_alsa_audio.c Tue Oct 13 09:35:37 2009 +0000
@@ -306,16 +306,16 @@
static void ALSA_PlayAudio(_THIS)
{
int status;
- snd_pcm_uframes_t samps_left;
+ snd_pcm_uframes_t frames_left;
const Uint8 *sample_buf = (const Uint8 *) mixbuf;
const int sample_size = ((int) (this->spec.format & 0xFF)) / 8;
swizzle_alsa_channels(this);
- samps_left = ((snd_pcm_uframes_t) this->spec.samples);
+ frames_left = ((snd_pcm_uframes_t) this->spec.samples);
- while ( samps_left > 0 ) {
- status = SDL_NAME(snd_pcm_writei)(pcm_handle, sample_buf, samps_left);
+ while ( frames_left > 0 ) {
+ status = SDL_NAME(snd_pcm_writei)(pcm_handle, sample_buf, frames_left);
if ( status < 0 ) {
if ( status == -EAGAIN ) {
SDL_Delay(1);
@@ -338,7 +338,7 @@
continue;
}
sample_buf += status * sample_size;
- samps_left -= status;
+ frames_left -= status;
}
}