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changeset 765:4c2ba6161939

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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.
author Sam Lantinga <slouken@libsdl.org>
date Sun, 04 Jan 2004 15:40:50 +0000
parents 974c0fb74bf8
children ed57c876700d
files src/audio/alsa/SDL_alsa_audio.c
diffstat 1 files changed, 7 insertions(+), 2 deletions(-) [+]
line wrap: on
line diff
--- a/src/audio/alsa/SDL_alsa_audio.c	Sun Jan 04 15:18:08 2004 +0000
+++ b/src/audio/alsa/SDL_alsa_audio.c	Sun Jan 04 15:40:50 2004 +0000
@@ -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 @@
 	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 @@
 	/* 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);
 }