[MEncoder-users] Skipping frames while copying video [BUGREPORT]

Aaron Digulla digulla at hepe.com
Mon Aug 7 20:19:47 CEST 2006

RC wrote:

>> The key point: It doesn't. By skipping frames, I end up with more
>> audio than video. 
> Well I could have said "trying to maintain sync", but I assumed that
> would be clear.  Most importantly, did you try disabling it by adding
> "-mc 0" (with/without -noskip)? You did not mention what effect
> it had, if any.

-mc 0 solved the problem and I ended up with a video where the audio and
the video had exactly the same "length".

> You said it was also duplicating frames, so it's not (just) shortening
> the video.  Do you know audio was exactly the same length as video in
> all your source files to begin with?  

The source material should have the same length for both streams; that's
why I was wondering why mencoder would want to drop/duplicate frames.

And it's dropping much more frames than it's duplicating.

>> Maybe this is a bug. Do you want to have a look at the input material?
>> I could upload a small file (4MB) which doesn't work.
> Always a good idea.

I uploaded a demo video as "copy-loosing-sync.mov" on the FTP server.
It's about 9MB and contains many skips and two duplicates.

The command I used to copy from Quicktime to an AVI container:

mencoder -ovc copy -oac pcm -o test.avi copy-loosing-sync.mov

Afterwards, I have 8.9s video and 9.5s audio. With "-mc 0", I get no
dropped or duplicated frames and the video and audio streams have the
same length.

I would expect mencoder not to drop or duplicate any frames while simply
copying a stream into a new container type.


Aaron "Optimizer" Digulla a.k.a. Philmann Dark
"It's not the universe that's limited, it's our imagination.
Follow me and I'll show you something beyond the limits."

More information about the MEncoder-users mailing list