[MEncoder-users] -ss and -endpos cutting creates very visible h264 artifacts

[Marc MERLIN]

On Tue, Feb 23, 2010 at 11:37:57PM -0800, Marc MERLIN wrote:
> I sometimes trim videos like this:
> mencoder -oac copy -ovc copy  -ss 0 -endpos 4:00 source.avi -o dest.avi
> 
> This worked fine until I started doing it with h264 encoded videos.
> 
> Problem is that the first resulting keyframe isn't computed right and
> you get very visible artifacts like here:
> http://www.youtube.com/watch?v=AZJkFHWaTRI
> (see upper right of the picture for the first 10 seconds)
> 
> I'm using SVN-r29237-4.4.1.
> 
> Is there a fix to this problem?

I've been working on that one a bit more.

Is whoever is using h264 using other tools to cut an h264 video?

Looking at it again, it may just be that cutting an h264 video without
re-encoding it, is not possible due to the time between consecutive
keyframes. Is that correct?

Thanks,
Marc
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