[MPlayer-users] -oac copy results in out of sync audio with mencoder ?

[a a]

If I transcode
the video but copy the audio the audio ends up totally out of sync. Is
there an option i need to keep the audio in sync when transcoding the
video

mencoder in.mkv -af volume=6:0 -mc 0 -oac copy -ovc x264 -x264encopts
preset=slow:tune=film:crf=15:frameref=15:fast_pskip=0:threads=auto:bitrate=2000
-nosub -vf scale=1280:-10 -o out.mkv
_______________________________________________
MPlayer-users mailing list
MPlaye...@mplayerhq.hu
https://lists.mplayerhq.hu/mailman/listinfo/mplayer-users

[Linards Ticmanis]

On 02/04/2012 01:13 PM, a a wrote:
> If I transcode
> the video but copy the audio the audio ends up totally out of sync. Is
> there an option i need to keep the audio in sync when transcoding the
> video
>
> mencoder in.mkv -af volume=6:0 -mc 0 -oac copy -ovc x264 -x264encopts
> preset=slow:tune=film:crf=15:frameref=15:fast_pskip=0:threads=auto:bitrate=2000
> -nosub -vf scale=1280:-10 -o out.mkv

To quote the manual: "-mc 0 should always be combined with -noskip for
mencoder, otherwise it will almost certainly cause A-V desync."

Also, -af doesn't make sense when you're copying the audio; have you
tried without?

--
Linards Ticmanis

[a a]

Thanks for the suggestion. I will try -noskip tonight and report what happens.

I actually tired without -mc 0 the first time and it did not work then I saw a comment that suggested -mc 0 to fix the issue.

The actual command I used did not have -af but i failed to remove it from the pasted command. I've been working on a small script to transcode but I keep running into 1 off issues (here the transcoded sound is really bad so I want to do a direct copy of the audio track).
-
After your comment about the manual I re-checked the man page and I do not see the comment that indicates one should use -noskip with -mc 0; can you provide a pointer to the manual that I should be using.

Thanks!

--- On Sat, 2/4/12, Linards Ticmanis <ticm...@gmx.de> wrote:

[Linards Ticmanis]

On 02/04/2012 04:43 PM, a a wrote:

> After your comment about the manual I re-checked the man page and I do not see the comment that indicates one should use -noskip with -mc 0; can you provide a pointer to the manual that I should be using.

It's in the man page of the current SVN version. Maybe it's not yet
there in the official release version you're probably using.

[a a]

noskip doesn't seem to help - i used this command line:

mencoder in.mkv -mc 0 -noskip -oac copy -ovc x264 -x264encopts preset=slow:tune=film:crf=15:frameref=15:fast_pskip=0:threads=auto:bitrate=2000 -nosub -vf scale=1280:-10 -of avi -o x.avi

Appreciate any other suggestions you might have.

--- On Sat, 2/4/12, Linards Ticmanis <ticm...@gmx.de> wrote:

From: Linards Ticmanis <ticm...@gmx.de>
Subject: Re: [MPlayer-users] -oac copy results in out of sync audio with mencoder ?
To: "MPlayer usage questions, feature requests, bug reports" <mplaye...@mplayerhq.hu>

[Linards Ticmanis]

On 02/04/2012 10:10 PM, a a wrote:
> noskip doesn't seem to help - i used this command line:
>
> mencoder in.mkv -mc 0 -noskip -oac copy -ovc x264 -x264encopts preset=slow:tune=film:crf=15:frameref=15:fast_pskip=0:threads=auto:bitrate=2000 -nosub -vf scale=1280:-10 -of avi -o x.avi
>
> Appreciate any other suggestions you might have.

Hmmm.... I don't really have any other "good" ideas. As for a
"not-so-good" idea, try encircling the problem - remove all options that
aren't 100% essential for what you're trying to do, then add them one by
one to see which causes the problem. Play around with the other stuff -
for example, what happens when you encode to to divx instead of x264, is
the problem still there. What happens when you do -ovc copy. What
happens when the input file is avi or mpeg instead of mkv. Try filters
that deal with FPS stuff - for example the harddup filter is sometimes
helpful. You get the idea, you just have to be an experimenting
scientist so to speak. Go on from there.

[Ron Johnson]

On 02/04/2012 03:10 PM, a a wrote:
> noskip doesn't seem to help - i used this command line:
>
>
> mencoder in.mkv -mc 0 -noskip -oac copy -ovc x264 -x264encopts preset=slow:tune=film:crf=15:frameref=15:fast_pskip=0:threads=auto:bitrate=2000 -nosub -vf scale=1280:-10 -of avi -o x.avi
>
> Appreciate any other suggestions you might have.
>

When converting MJPEG .mov files to DVD-compatible MPEG2 files, I was
faced with a similar problem. The solution was a 2-step conversion:

VCODEC="vcodec=mpeg2video:aspect=4/3:vbitrate=6000:trell:nr=100"
mencoder \
*.mov \
-o ${FOO}.avi \
-ovc lavc -lavcopts $VCODEC \
-oac pcm -channels 1 -srate 8000

ffmpeg -i ${FOO}.avi -target ntsc-dvd ${FOO}-0.0.mpeg

This example is tuned to my specific circumstance, but should be
adjustable to yours.

--
How does being physically handicapped make me Differently-Abled?
What different abilities do I have?

[a a]

I'm not sure if I understand what hte second pass is doing here;but if I use pcm or anything but copy for oac then the audio is in sync. Its only when I try to copy the audio that it ends up out of sync.

I can't get mencoder to just copy the video; but I was thinking I could use mkvextra and merge to insert the original audio track.

Still I don't understand why the copy ends up with the audio out of sync :(

--- On Sat, 2/4/12, Ron Johnson <ron.l....@cox.net> wrote:

From: Ron Johnson <ron.l....@cox.net>
Subject: Re: [MPlayer-users] -oac copy results in out of sync audio with mencoder ?
To: "MPlayer usage questions, feature requests, bug reports" <mplaye...@mplayerhq.hu>

[a a]

It seems that running mkvmerge as a second pass fixes the issue

mkvmerge -o x.mkv  in.avi
-
no clue why but sounds like an issue with the keyframes ? The new file is marginally smaller (about 1%).

--- On Sun, 2/5/12, a a <you2...@yahoo.com> wrote:

[mx2927]

Have you tried -mc 0 -vf harddup (no -noskip) in mencoder ?