[MPlayer-users] 3pass mencoding creates shorter length video stream than the original

[D Richard Felker III]

On Sun, Jan 12, 2003 at 06:01:48PM +0200, Georgi Hristov wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> hi,
> 
> i'd like to submit some kind of a bugreport, but the bug is in the end file,
> not in the information mencoder prints. for the last 2 movies i made i used
> cvs versions from 2003 01 03 and then from yesterdays cvs with same problem.
> I reencode an ac3 movie to vbr mp3 and lower the video rate to fit 1cd, in 3
> passes. problem is the frameno.avi is fine, and then the resulting movie
> after the 3rd pass is few seconds smaller, and with tottaly unsynced sound.
> i tried audiodumping the frameno, and then combining it with the video of
> the original with virtualdub (plus divx502 reencoding)- the result is fine,
> plus i've done this exercise a lot of times before, and there must be
> something in mencoder these days.
> ---
> Video stream:  702.133 kbit/s  (87766 bps)  size: 617311848 bytes  7033.563
> secs  169266 frames
> 
> ^^^^^^
> Audio stream:  117.456 kbit/s  (14682 bps)  size: 103274160 bytes  7034.040
> secs
> ---
> ^^^^^
> 
> 
> then i got a pretty long list of these in the begining, but this was never a
> problem before, afair.
> ---
> Pos: 515.9s  12934f ( 6%)  22fps Trem: 132min 688mb  A-V:0.000 [644:117]
> Skipping frame!!!
> ---

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.

Rich