[MEncoder-users] HDTV transcode loses 5.1 ac3 Audio

R.L. Horn lists at eastcheap.org
Mon Sep 1 03:01:58 CEST 2008

On Sat, 30 Aug 2008, Dan Shoup wrote:

> Mencoder.exe -i "E:\Dir\filename.mpg” -of avi -oac copy -ovc xvid 
> -xvidencopts fixed_quant=4 -vf scale=1024:576 -o “E:\Dir\filename.avi”
> This works, but I only get 2-channel audio. I have also tried adding 
> "–channels 6"

The -channels option isn't meaningful with the framecopy "encoder."

-oac copy merely copies the audio stream without alteration.  If it's 
6-channel in, you should get 6-channel out, and I don't see how mencoder 
could do otherwise.

> MEncoder dev-SVN-rUNKNOWN-4.2.1-sjlj (C) 2000-2007 MPlayer Team

Hmm, that's not good.  Not only is it an older mencoder version, but we've 
no clue as to which version it is...

> AUDIO: 48000 Hz, 2 ch, s16le, 384.0 kbit/25.00% (ratio: 48000->192000)

> audiocodec: framecopy (format=2000 chans=2 rate=48000 bits=16 B/s=48000 
> sample-1 )

I think you can safely ignore these messages.  liba52, by default, 
downmixes to two channels, which affects the information it returns about 
a stream (the number of channels is a bit of an abstraction with AC3). 
However, you're not decoding the stream, just copying it.  If you play the 
resulting file with mplayer -channels 6, you should get your six-channel 

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