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Old 23rd November 2021, 15:09   #1  |  Link
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Cutting Video with MKVmerge?


Every once in a while I'll make a remux which has coloured bars or excess padding at the start or end of the movie which really annoys me so I was wondering if anyone could direct or point me to a step by step guide which could help me cut the coloured bars or padding away. I keep seeing cut to iframe etc but am still new to this but do know all the basics. Also I'm using the latest mkvmerge. Any help would be appreciated.
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Old 24th November 2021, 06:57   #2  |  Link
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Cutting at specific frames and cutting at I frames are very different operations. With the current consumer video formats it is actually impossible to cut at a specific frame without losing quality, at least in a few frames near the cut.

Because frames are dependent on the previous frames, you need all the frames up to the last I frame in order to decode a later frame. This is why you sometimes see digital video go into that blocky smeary mess when the connection is poor. The decoder lost the I frame or a previous P frame and is decoding P or B frames without the original reference blocks.

This means frame accurate cutting of video requires decoding and re-encoding of the entire video or only those frames missing reference blocks, which is sometimes called "Smart Rendering".
How to cut video frame accurate without encoding?
madVR options explained
Asmodian is offline   Reply With Quote
Old 24th November 2021, 11:32   #3  |  Link
Matroska find' ich toll
Join Date: Apr 2008
Posts: 1,243
My opinion:

Never ever cut or join/append mkv's, because there is a Matroska design issue which often appears.

The best way is to use ordered chapters. Only with this method/feature you can virtually cut frame accurate!
chapterEditor || Matroska-Playback || hSplit || DiscShare
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Old 25th November 2021, 23:20   #4  |  Link
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Originally Posted by hubblec4 View Post
Never ever cut or join/append mkv's, because there is a Matroska design issue which often appears.
Can you elaborate about this design issue? I often use MKVToolNix to cut at keyframes and never had a problem yet.
karbre is offline   Reply With Quote
Old 29th November 2021, 10:30   #5  |  Link
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I'd be keen to know what the issue is too, as I use MKVToolNixGUI to cut and/or join MKVs regularly without any problem.

If you open an MKV with MPC-HC and navigate with the keyboard left and right arrow keys while holding down the shift key, you'll jump between keyframes.
When you're at the appropriate keyframe, use the Navigate/GoTo menu (CTRL+G) to get the frame number. Use it when cutting with MKVToolNix (split after frame number). Of course there's no guarantee there'll be a keyframe where you want to cut. Sometimes there is, sometimes not.
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