[MPlayer-users] reencoding of audio?

[D Richard Felker III]

On Tue, Feb 25, 2003 at 12:33:59AM +0000, Martin Collins wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> On Tue, 25 Feb 2003 00:33:01 +0100
> Konstantinos Blatzonis <Kosta at gmxpro.net> wrote:
> 
> > I encoded some VOBs to one divx_avi. When I did this I forgott to
> > raise up the inputgainlevel of mencoder, so that the sound is - even
> > when mixer is on 100% - not loud enought. What can I do gain up the
> > sound?
> 
> I had to do this once. First split out the audio:
> mplayer -ao pcm -aofile quiet.wav -ovc dummy quietmovie.avi
> 
> Then hike the volume:
> sox -v 1.5 quiet.wav loud.wav
> 
> Then mux the audio back in with the video:
> mencoder -oac mp3lame -audiofile loud.wav -ovc copy -o loudmovie.avi quietmovie.avi
> 
> Or something like that. Adjust the details to your needs.

Huh? This is nonsense and will probably desync A/V! Just use the
-lameopts vol=... option to reencode. Or, if you want to try demuxing
and remuxing (and hope A/V sync doesn't break), you can dump the mp3
track out, then use a lossless mp3 volume adjustor (there's one on
freshcrap, iirc) and remux it. Then you won't lose quality like with
reencoding...

Rich