[MEncoder-users] mkv to hard sub avi to m4v command line options and sync problems

[Reimar Döffinger]

On Sun, Jan 17, 2010 at 09:40:39AM -0600, James Hastings-Trew wrote:
> Reimar Döffinger wrote:
> >On Sun, Jan 17, 2010 at 07:55:06AM -0600, James Hastings-Trew wrote:
> >>Reimar Döffinger wrote:
> >>>On Sun, Jan 17, 2010 at 07:17:06AM -0600, James Hastings-Trew wrote:
> >>>>v4r4n wrote:
> >>>>>$> mencoder -oac copy -ovc raw -sub subtitles.srt -sub-bg-alpha 255 -utf8 -o
> >>>>>output.srt.avi input.avi
> >>>>>
> >>>>>to make a large raw with baked subtitles, then Handbrake to re-encode that
> >>>>>into an iPod .m4v file.  This works well enough, but the original visual
> >>>>>artifacts that I saw in the raw are still there.
> >>>>I'm not sure how you could expect it to be otherwise. That command
> >>>>line leads me to believe the artifacts are part of the original .mkv
> >>>>file, since raw would not add any artifacts of it's own.
> >>>Wrong, it will introduce decoding errors if you do not use -noskip.
> >>Are you saying that it will skip decoding frames, not just skip
> >>storing them?
> >
> >?? No idea what you mean.
> >I mean it will skip storing the encoded data belong to whatever
> >frame it decides to drop, and that frame may have been referenced
> >by later encoded frames which is does copy - this breaks decoding
> >of those frames.
> >So with -ovc raw and an encoded format a skipped frame (as can happen
> >when you do not use -noskip) can mean there is one frame missing in
> >the resulting frame and there are possible another several 100
> >that are there bug can not be decoded correctly.
> >For those that can not be decoded correctly, FFmpeg uses error-concealment
> >and since that is quite good you usually see it only as the output
> >looking blocky, blurry or otherwise low quality.
> >The error-concealment can be tuned with -lavdopts ec=...  but it seems
> >it can't be disabled...
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> >MEncoder-users at mplayerhq.hu
> >https://lists.mplayerhq.hu/mailman/listinfo/mencoder-users
> >
> I thought -ovc raw just stored uncompressed video, not encoded frames.

Argh. Yes you are completely right.
I somehow thought of -ovc copy, please disregard anything I said unless you
want to know something about -ovc copy.
Sorry.