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alsa: Simplified PlayDevice and CaptureFromDevice.

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This commit is contained in:
Ryan C. Gordon
2023-09-30 12:23:28 -04:00
parent 776d9d0ee3
commit 0471a93706
1 changed files with 26 additions and 45 deletions
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65
src/audio/alsa/SDL_alsa_audio.c
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@@ -364,32 +364,22 @@ static int ALSA_PlayDevice(SDL_AudioDevice *device, const Uint8 *buffer, int buf
device->hidden->swizzle_func(device, sample_buf, frames_left); device->hidden->swizzle_func(device, sample_buf, frames_left);
while ((frames_left > 0) && !SDL_AtomicGet(&device->shutdown)) { while ((frames_left > 0) && !SDL_AtomicGet(&device->shutdown)) {
int status = ALSA_snd_pcm_writei(device->hidden->pcm_handle, const int rc = ALSA_snd_pcm_writei(device->hidden->pcm_handle, sample_buf, frames_left);
sample_buf, frames_left); //SDL_Log("ALSA PLAYDEVICE: WROTE %d of %d bytes", (rc >= 0) ? ((int) (rc * frame_size)) : rc, (int) (frames_left * frame_size));
//SDL_Log("ALSA PLAYDEVICE: WROTE %d of %d bytes", (status >= 0) ? ((int) (status * frame_size)) : status, (int) (frames_left * frame_size)); SDL_assert(rc != 0); // assuming this can't happen if we used snd_pcm_wait and queried for available space.
if (status < 0) { if (rc < 0) {
if (status == -EAGAIN) { // !!! FIXME: should this happen if we used snd_pcm_wait and queried for available space?! SDL_assert(rc != -EAGAIN); // assuming this can't happen if we used snd_pcm_wait and queried for available space. snd_pcm_recover won't handle it!
// Apparently snd_pcm_recover() doesn't handle this case - does it assume snd_pcm_wait() above? const int status = ALSA_snd_pcm_recover(device->hidden->pcm_handle, rc, 0);
SDL_Delay(1);
continue;
}
status = ALSA_snd_pcm_recover(device->hidden->pcm_handle, status, 0);
if (status < 0) { if (status < 0) {
// Hmm, not much we can do - abort // Hmm, not much we can do - abort
SDL_LogError(SDL_LOG_CATEGORY_AUDIO, SDL_LogError(SDL_LOG_CATEGORY_AUDIO, "ALSA write failed (unrecoverable): %s", ALSA_snd_strerror(rc));
"ALSA write failed (unrecoverable): %s",
ALSA_snd_strerror(status));
return -1; return -1;
} }
continue; continue;
} else if (status == 0) {
// !!! FIXME: should this happen if we used snd_pcm_wait and queried for available space?!
// No frames were written (no available space in pcm device). Allow other threads to catch up.
SDL_Delay((frames_left / 2 * 1000) / device->spec.freq);
} }
sample_buf += status * frame_size; sample_buf += rc * frame_size;
frames_left -= status; frames_left -= rc;
} }
return 0; return 0;
@@ -409,40 +399,31 @@ static Uint8 *ALSA_GetDeviceBuf(SDL_AudioDevice *device, int *buffer_size)
static int ALSA_CaptureFromDevice(SDL_AudioDevice *device, void *buffer, int buflen) static int ALSA_CaptureFromDevice(SDL_AudioDevice *device, void *buffer, int buflen)
{ {
Uint8 *sample_buf = (Uint8 *)buffer;
const int frame_size = SDL_AUDIO_FRAMESIZE(device->spec); const int frame_size = SDL_AUDIO_FRAMESIZE(device->spec);
const int total_frames = buflen / frame_size;
snd_pcm_uframes_t frames_left = total_frames;
SDL_assert((buflen % frame_size) == 0); SDL_assert((buflen % frame_size) == 0);
while ((frames_left > 0) && !SDL_AtomicGet(&device->shutdown)) { const snd_pcm_sframes_t total_available = ALSA_snd_pcm_avail(device->hidden->pcm_handle);
int status = ALSA_snd_pcm_readi(device->hidden->pcm_handle, const int total_frames = SDL_min(buflen / frame_size, total_available);
sample_buf, frames_left);
if (status == -EAGAIN) { const int rc = ALSA_snd_pcm_readi(device->hidden->pcm_handle, buffer, total_frames);
break; // Can this even happen? Go back to WaitCaptureDevice, where the device lock isn't held.
} else if (status < 0) { SDL_assert(rc != -EAGAIN); // assuming this can't happen if we used snd_pcm_wait and queried for available space. snd_pcm_recover won't handle it!
//printf("ALSA: capture error %d\n", status);
status = ALSA_snd_pcm_recover(device->hidden->pcm_handle, status, 0); if (rc < 0) {
const int status = ALSA_snd_pcm_recover(device->hidden->pcm_handle, rc, 0);
if (status < 0) { if (status < 0) {
// Hmm, not much we can do - abort // Hmm, not much we can do - abort
SDL_LogError(SDL_LOG_CATEGORY_AUDIO, SDL_LogError(SDL_LOG_CATEGORY_AUDIO, "ALSA read failed (unrecoverable): %s\n", ALSA_snd_strerror(rc));
"ALSA read failed (unrecoverable): %s\n",
ALSA_snd_strerror(status));
return -1; return -1;
} }
break; // Go back to WaitCaptureDevice, where the device lock isn't held. return 0; // go back to WaitDevice and try again.
} else if (rc > 0) {
device->hidden->swizzle_func(device, buffer, total_frames - rc);
} }
//printf("ALSA: captured %d bytes\n", status * frame_size); //SDL_Log("ALSA: captured %d bytes\n", rc * frame_size);
sample_buf += status * frame_size;
frames_left -= status;
}
device->hidden->swizzle_func(device, buffer, total_frames - frames_left); return rc * frame_size;
return (total_frames - frames_left) * frame_size;
} }
static void ALSA_FlushCapture(SDL_AudioDevice *device) static void ALSA_FlushCapture(SDL_AudioDevice *device)