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

[Martijn van Beurden]

Marc MERLIN schreef:
> On Sun, Feb 28, 2010 at 08:30:20AM +0100, Reimar Döffinger wrote:
>   
>> On Sat, Feb 27, 2010 at 11:23:16PM -0800, Marc MERLIN wrote:
>>     
>>>> Copying the video completely into a different format forst, e.g. mkv, with ffmpeg or mkvmerge
>>>> or so might fix it...
>>>>         
>>> Yes, if I re-encode it will likely work. It just takes a long time to
>>> re-encode and loses quality :)
>>>       
>> Not re-encoding (mkvmerge can't even do encoding AFAIK), just copying it.
>> It won't allow you to cut more precisely, but at least there should be
>> no artefacts.
>>     
>
> Thanks. It was worth a shot.
>
> I tried this:
> mkvmerge -o out.mkv 491_Keystone2_treerun_fall.avi 
> mencoder -ss 0:1:20 -endpos 0:0:30 -oac copy -ovc copy out.mkv -o out2.mkv 
>
> And it's the same problem, out2.mkv still seems to be missing a keyframe and
> the video only looks ok after about 10 seconds.
>
> Marc
>   

I think he meant copy the whole video (without ss and endpos) to another 
container, which rebuilds the index, and then trying to transcode with 
ss and endpos. You could try it with an EDL and -hr-edl-seek too, as 
that decodes the whole video, but encodes just the parts you need. As 
this looks like a decode problem, that should work.