From cff45873ec91f0d16c486f210c101f3bb35d53e8 Mon Sep 17 00:00:00 2001 From: Sam Lantinga Date: Sun, 4 Jan 2004 15:40:50 +0000 Subject: [PATCH] Editors Note: The original patch was modified to use SDL_Delay() instead of nanosleep because nanosleep may not be portable to all systems using SDL with the ALSA backend. This may be a moot point with the switch to blocking writes anyway... Date: Sat, 27 Dec 2003 21:47:36 +0100 From: Michel Daenzer To: Debian Bug Tracking System Subject: [SDL] Bug#225252: [PATCH] ALSA fixes Package: libsdl1.2debian-all Version: 1.2.6-2 Severity: normal Tags: patch For SDL 1.2.6, the ALSA backend was changed to call snd_pcm_open() with SND_PCM_NONBLOCK. That's a good idea per se, however, it causes high CPU usage, interrupted sound and stuttering in some games here. Taking a nanosleep whenever snd_pcm_writei() returns -EAGAIN fixes this, but I think it's more efficient to use blocking mode for the actual sound playback. Feedback from the SDL and ALSA lists appreciated. The patch also fixes the default ALSA device to be used. --- src/audio/alsa/SDL_alsa_audio.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/src/audio/alsa/SDL_alsa_audio.c b/src/audio/alsa/SDL_alsa_audio.c index b147480aa..cc9861535 100644 --- a/src/audio/alsa/SDL_alsa_audio.c +++ b/src/audio/alsa/SDL_alsa_audio.c @@ -45,7 +45,7 @@ #define DRIVER_NAME "alsa" /* The default ALSA audio driver */ -#define DEFAULT_DEVICE "plughw:0,0" +#define DEFAULT_DEVICE "default" /* Audio driver functions */ static int ALSA_OpenAudio(_THIS, SDL_AudioSpec *spec); @@ -146,17 +146,19 @@ static void ALSA_PlayAudio(_THIS) int status; int sample_len; signed short *sample_buf; - + sample_len = this->spec.samples; sample_buf = (signed short *)mixbuf; while ( sample_len > 0 ) { status = snd_pcm_writei(pcm_handle, sample_buf, sample_len); if ( status < 0 ) { if ( status == -EAGAIN ) { + SDL_Delay(1); continue; } if ( status == -ESTRPIPE ) { do { + SDL_Delay(1); status = snd_pcm_resume(pcm_handle); } while ( status == -EAGAIN ); } @@ -316,6 +318,9 @@ static int ALSA_OpenAudio(_THIS, SDL_AudioSpec *spec) /* Get the parent process id (we're the parent of the audio thread) */ parent = getpid(); + /* Switch to blocking mode for playback */ + snd_pcm_nonblock(pcm_handle, 0); + /* We're ready to rock and roll. :-) */ return(0); }