[MPlayer-dev-eng] Re: ao_plugin play() problems - fix suggestions

[Stephen Davies]

On Mon, 10 Dec 2001, Stephen Davies wrote:

> (2) ao2 drivers should limit value returned from get_space
> 
> - ao2 drivers should be adjusted to always return a get_space value that
>   is less than MAX_OUTBURST, and that "suits" the driver.
>   For instance, ao_oss would take fragment size into account when
>   calculating a value to return.

Well - I tried this out in ao_oss and it seems to do the job pretty
smoothly for me.

Patch as so:

Index: libao2/ao_oss.c
===================================================================
RCS file: /cvsroot/mplayer/main/libao2/ao_oss.c,v
retrieving revision 1.15
diff -u -r1.15 ao_oss.c
--- libao2/ao_oss.c	4 Dec 2001 17:54:08 -0000	1.15
+++ libao2/ao_oss.c	10 Dec 2001 21:57:35 -0000
@@ -241,7 +241,10 @@
 #ifdef SNDCTL_DSP_GETOSPACE
   if(ioctl(audio_fd, SNDCTL_DSP_GETOSPACE, &zz)!=-1){
       // calculate exact buffer space:
-      return zz.fragments*zz.fragsize;
+      playsize = zz.fragments*zz.fragsize;
+      if (playsize > MAX_OUTBURST)
+	playsize = (MAX_OUTBURST / zz.fragsize) * zz.fragsize;
+      return playsize;
   }
 #endif
 

Shall I commit that?

Anders - you will have trouble, though, if you want to add or subtract
some samples in a plugin, that is, move the data length away from a
multiple of a fragment.  I reckon buffering in ao_plugin is the only
proper fix for that to work.

Steve