[MPlayer-users] mixed ac3 5.1 and 2 channel

[Ariel]

Since no one else replied I guess I have to hack it myself. This patch 
(included below) worked nicely. It basically forces the resampling code to 
always assume everything has 6 channels. (If you ask for 6 channels on the 
command line.) It works perfectly.

I don't understand the point of the resampling code! It certainly doesn't 
seem to be doing anything useful.

Patch:

diff -u -r mplayer-1.0-pre7.orig/liba52/resample_c.c mplayer-1.0-pre7/liba52/resample_c.c
--- mplayer-1.0-pre7.orig/liba52/resample_c.c   2005-10-02 03:27:44.000000000 -0400
+++ mplayer-1.0-pre7/liba52/resample_c.c        2005-10-02 03:28:48.000000000 -0400
@@ -179,5 +179,6 @@
         if(ch==6) return a52_resample_3F_2R_LFE_to_6_C;
         break;
      }
+    if(ch==6) return a52_resample_3F_2R_LFE_to_6_C;
      return NULL;
  }
diff -u -r mplayer-1.0-pre7.orig/liba52/resample_mmx.c mplayer-1.0-pre7/liba52/resample_mmx.c
--- mplayer-1.0-pre7.orig/liba52/resample_mmx.c 2005-10-02 03:28:02.000000000 -0400
+++ mplayer-1.0-pre7/liba52/resample_mmx.c      2005-10-02 03:19:11.000000000 -0400
@@ -512,5 +512,6 @@
         if(ch==6) return a52_resample_3F_2R_LFE_to_6_MMX;
         break;
      }
+    if(ch==6) return a52_resample_3F_2R_LFE_to_6_MMX;
      return NULL;
  }

 	-Ariel


On Fri, 23 Sep 2005, Ariel wrote:

>
> I have a mixed ac3 stereo and 5.1 stream (from an HDTV capture).
>
> Once MPlayer sees that it starts with a stereo stream, it refuses to play the 
> rest in 5.1 (the audio gets quieter at the transition point - so it noticed 
> something, but it's stereo).
>
> If I use avi tools to add in a 1 second 5.1 stream before the avi, and then 
> play that: MPlayer starts with 5.1, then switches to stereo with hissing from 
> the other speakers, then switches back to 5.1.
>
> (Obviously I use -channels 6 it both cases.)
>
> It looks like it needs to see at least a little 5.1 at the start to enable 
> channels 6, otherwise it's forced off.
>
> I would like instead that with channels 6 it's always on. If the stream 
> happens to be stereo, then just play stereo.
>
> As a point of comparison xine does it properly.
>
> With an mpeg MPlayer says:
> Unimplemented resampler for mode 0x2 -> 6 channels conversion - Contact 
> MPlayer developers!
> Unimplemented resampler for mode 0x2 -> 5 channels conversion - Contact 
> MPlayer developers!
> Unimplemented resampler for mode 0x2 -> 4 channels conversion - Contact 
> MPlayer developers!
> Unimplemented resampler for mode 0x2 -> 3 channels conversion - Contact 
> MPlayer developers!
>
> With an avi it seems to look at the avi header - which is wrong, since the 
> file is mixed, and just plays in stereo with no messages. If I edit the avi 
> header to change 2 channels to 6, then MPlayer says the same thing it says 
> with the mpeg.
>
> So basically don't trust the avi header as far as ac3 channels goes.
>
> 	-Ariel
>
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