[MPlayer-dev-eng] Patch to prevent blocking in ao_oss

[Fredrik Kuivinen]

Hello

Attached is a small patch that disables sound if the audio device is used by
another program. Instead of blocking which mplayer currently do.

BTW currently a lot of things are detected at compile time such as MMX, DGA, 
3DNOW etc. And in the sources there are lots of #ifdef MMX etc... Are there
any plans of changing this into runtime detection instead?

/ Fredrik Kuivinen

-------------- next part --------------
--- /home/ksorim/src/MPlayer-20011023/libao2/ao_oss.c	Thu Oct  4 20:25:50 2001
+++ libao2/ao_oss.c	Fri Oct 26 16:56:05 2001
@@ -7,6 +7,7 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
+#include <errno.h>
 //#include <sys/soundcard.h>
 
 #include "../config.h"
@@ -112,12 +113,21 @@
   if (verbose)
     printf("audio_setup: using '%s' dsp device\n", dsp);
 
-  audio_fd=open(dsp, O_WRONLY);
+  /* The open call will block if some other program is using the device if we
+   * don't pass O_NONBLOCK to open */
+  audio_fd=open(dsp, O_WRONLY|O_NONBLOCK);
   if(audio_fd<0){
-    printf("Can't open audio device %s  -> nosound\n",dsp);
+    printf("Can't open audio device %s: %s  -> nosound\n", dsp, strerror(errno));
     return 0;
   }
 
+  /* Remove O_NONBLOCK that we got from open */
+  if(fcntl(audio_fd, F_SETFL, 0) != 0) {
+      printf("fcntl failed: %s This should never happen. " \
+             "Please report as a bug\n");
+      return 0;
+  }
+
   ao_format=format;
   ioctl (audio_fd, SNDCTL_DSP_SETFMT, &ao_format);
   if(format == AFMT_AC3 && ao_format != AFMT_AC3) {
@@ -191,17 +201,25 @@
 // stop playing and empty buffers (for seeking/pause)
 static void reset(){
     uninit();
-    audio_fd=open(dsp, O_WRONLY);
+    audio_fd=open(dsp, O_WRONLY|O_NONBLOCK);
     if(audio_fd<0){
-	printf("\nFatal error: *** CANNOT RE-OPEN / RESET AUDIO DEVICE ***\n");
+	printf("\nFatal error: %s *** CANNOT RE-OPEN / RESET AUDIO DEVICE " \
+               "***\n", strerror(errno));
 	return;
     }
 
-  ioctl (audio_fd, SNDCTL_DSP_SETFMT, &ao_format);
-  if(ao_format != AFMT_AC3) {
-  ioctl (audio_fd, SNDCTL_DSP_STEREO, &ao_channels);
-  ioctl (audio_fd, SNDCTL_DSP_SPEED, &ao_samplerate);
-  }
+    if(fcntl(audio_fd, F_SETFL, 0) != 0) {
+        printf("Error during fcntl: %s While re-opening audio device. This " \
+               "should never happen. Please report as a bug.\n", 
+               strerror(errno));
+        return;
+    }
+
+    ioctl (audio_fd, SNDCTL_DSP_SETFMT, &ao_format);
+    if(ao_format != AFMT_AC3) {
+        ioctl (audio_fd, SNDCTL_DSP_STEREO, &ao_channels);
+        ioctl (audio_fd, SNDCTL_DSP_SPEED, &ao_samplerate);
+    }
 }
 
 // stop playing, keep buffers (for pause)