[MEncoder-users] HDTV transcode loses 5.1 ac3 Audio

Dan Shoup deshoup at hotmail.com
Mon Sep 1 15:46:42 CEST 2008

Thanks for the help!  ...I think that means I have a new question...why won't my file play in mplayer using 5.1 audio?  I play it in GBPVR and it comes out in 5.1 (this was originally the only player I had tested it in as this was my end goal).  When I play it in mencoder I get 2-channel stereo...so it's no wonder it is transcoding in 2-channel.  So I started playing with different audio players.  VLC media player and Mpeg2Cut also give me 2-channel audio.  Microsoft MediaPlayer won't play the file at all.  In case it helps, my GBPVR player is configured to use the NVIDIA Audio Decoder (which does AC3 pass through to my digital receiver).  However, with GBPVR I most definitely get 5.1 output (receiver indicates this, but I can also hear the difference), so I know the information is there in the file, but it is obviously hard for some players to see that.  Any suggestions?  I assume if I can get mplayer to output 5.1 audio I would be able to transcode with the -aoc copy command and end up with 5.1 as well?

> Date: Sun, 31 Aug 2008 20:01:58 -0500> From: lists at eastcheap.org> To: mencoder-users at mplayerhq.hu> Subject: Re: [MEncoder-users] HDTV transcode loses 5.1 ac3 Audio> > 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 > audio.
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