[MPlayer-users] Question about 3-pass encoding...

[Hadmut Danisch]

Hi,

just a question about encoding in three passes: 

There are plenty of web pages, howtos and wikis, explaining how to do
the 2-pass encoding to get optimized image quality. Most oft them
recommend to do a 3-pass encoding, where the first pass encodes the 
audio channel to avoid encoding it twice. The second and third 
pass would not encode the audio, but take it from the existing file. 
All examples look like this:

mencoder -dvd 2 -ovc frameno -o frameno.avi -oac mp3lame -lameopts vbr=3
mencoder -dvd 2 -ovc lavc -lavcopts vcodec=mpeg4:vpass=1 -oac copy -o movie.avi
mencoder -dvd 2 -ovc lavc -lavcopts vcodec=mpeg4:vpass=2 -oac copy -o movie.avi


What I do not understand: What makes mencoder take the  preprocessed
audio in the second and third pass?  As I understand the parameters, 
-oac copy would copy the audio unprocessed from the input file. What
would cause mencoder to read frameno.avi?

regards
Hadmut