[MPlayer-users] RE: 3pass mencoding creates shorter length video

[Georgi Hristov]

>You need a lot more info for us to really help. For example, do you
>see a lot of skipped or duplicated frame messages? What format is the
>original movie? I assume it's a DVD, but is it NTSC or PAL? If it's
>NTSC from a theatrical movie, you need -ofps 23.976. If it's
>made-for-tv NTSC, it should work without any special options. Normal
>PAL should also work as-is, but some PAL DVDs are 50 fps
>field-encoded, in which case 3pass encoding DOES NOT WORK and you have
>to just do normal encoding without the -ovc frameno pre-pass. If this
>is the case you can do something like:

>mencoder -dvd 1 -oac copy -ovc lavc -lavcopts vpass=1:...
>mencoder -dvd 1 -oac mp3lame -ovc lavc -lavcopts vpass=2:...

>to avoid wasting time encoding audio twice. But be aware that you MUST
>use some sort of audio on the first pass; -nosound will ruin A/V sync.

>If these tips don't help, post back with a full report.

hi,

no, it's a 2cd ac3 avi, which i'm converting to a 1cd vbr mp3, with a little
lower video bitrate. it's just a normal 23.976 framerate movie, and the
thing that made me report it is that virtualdub did handle it ok. to arpi's
question - yes, i did get lots of skipped frames in the begining at about 6%
of the job, but for what i remember it was not a problem in other cases.

here is the script i used:

#!/bin/bash
mencoder -ovc frameno -oac mp3lame -lameopts vbr=3:br=128:vol=3
"sim1.avi" -o "frameno.avi"
mencoder -ovc lavc -oac copy -lavcopts vbitrate=702:vcodec=mpeg4:vpass=1
"sim1.avi" -o "out.avi"
mencoder -ovc lavc -oac copy -lavcopts vbitrate=702:vcodec=mpeg4:vpass=2
"sim1.avi" -o "out.avi"

 ( i did have a pause between pass 1 & 2 to get the bitrate of 702 from the
recomendations )

the strange thing is that i've used the same routine for other movies, and
it never failed - so it's either wrong frames in the movie, or some new bug.
i'll do some more tests (though they take helluva time) and if it repeats
with other movies, i'll report to you.

regards,
joro