[MPlayer-users] Mencoder audio pass messes up video pass

[Sumant S.R. Oemrawsingh]

On Fri, Jul 04, 2003 at 10:49:23PM -0400, D Richard Felker III wrote:
> > However, when I completely skip the first (audio) pass and directly encode
> > the video first (with oac copy), the dvd is nicely encoded. But then I have
> > a52 (AC3) audio, which takes a bit too much space, which I'd rather spend on
> > audio.[4,5]
> 
> If you skip the audio pass at the beginning (and I would definitely
> recommend skipping it), then don't use -oac copy for the video passes.
> Actually, you can perhaps use it for the first video pass for speed,
> since you'll be throwing away the output of that one anyway, but for
> the final pass, use -oac mp3lame with your desired -lameopts.

Hi,

Thank you very much for your help. Do you recommend to always skip the
audio pass, or do you only recommend it to avoid this problem? If you
recommend to always skip the audio pass, why?

This, indeed, works on this particular DVD I have here. But three-pass
encoding works well for other DVD's. It gives me the advantage of not having
to use a constant audio bitrate and use the video bitrate that mencoder
suggests. Usually when I use abr with a bitrate of, say, 128, it averages
out at around 118 or even lower. I have even fooled around with vbr and
quality (on DVD's where I found sound to be more important than video).  So
if I calculate the videobitrate in advance, mencoder always suggests a
higher bitrate to fill the CD. And very often, I've noticed that this makes
some difference. That's why I find the first (audio) pass useful.

Anyway, I can circumvent the problem for this particular DVD with your
solution. But I'd still like to know: is this a `feature' in mencoder, the
decoding libraries or the DVD?

Thanks again,
Sumant
 
-- 
Sumant S. R. Oemrawsingh
Sumant.Oemrawsingh at WolMail.NL