Incorrect video cut timing on MKV video with lossless quality

[may5224]

Hi,

I REALLY do not know the search term for my problem, have been searching for one day now and can't find what I'm looking for.
Please redirect me if this post already exists somewhere on the internet.

So, with that being said, here's the issue I'm facing:

I am trying to cut a part of an MKV file with lossless quality. I have been using the program "Lossless Cut" and MKVMerge to cut MKV videos. But this time it does not work properly.

Here's the scenario:
I have an MKV file, the intro of this video is about 20 seconds long and I want to remove it by cutting it out of the video.

Whenever I specify the time in MKVMERGE to 00:00:20, it cuts the video properly into two files. But when I open the edit file, it still plays a couple of seconds of the intro. It doesn't cut the exact time from it. When I try to increase it from 00:00:20 to let's say 00:00:22, it just skips too much of the video.

It's like there is a gap in my MKV video. When I watch the unedited video and skip to let's say 25 minutes forward, it just skips more like 25 minutes and 3 seconds (not the exact time I give it).

It's like the audio file is longer than the video file but they're still in sync or the other way around.

How can I fix this? I have this with multiple files but not all.
If you don't understand my question then let me know, I will do my best to explain it better then. (as I said, it's hard for me to describe)

P.S. When I try to watch the video from start to finish without skipping, it works and loads properly without any issues.

How can I fix this issue? And what can cause this problem?

Hope you get the point... thanks in advance.


EDIT: to put it simply, I want to cut off the first 20 seconds of a video precisely and am not able to do that using "Lossless Cutter" or "MKVMerge" or "MKV Cutter" In a fast way without reencoding the entire video. It should only take me a couple of seconds to cut. (I'm looking for a program that might be able to do this if this exists or is even possible.)

[jagabo]

Lossless cutters can only cut on keframes. Keyframes may be several seconds apart.

https://en.wikipedia.org/wiki/Group_of_pictures

Players can seek to any frame but often have a setting that lets it seek to the nearest keyframe (because decoding is faster that way).

[sambat]

https://www.videohelp.com/software/MKV-Cutter

Has to be h264, so might not be suitable for your case.
The "cutter' part refers to the part that is to be saved (select Start Cut and End Cut).
Only the cut point is re-encoded.
I've used this to cut up an mkv file that was out of sync in one section, so that I could re-sync the part then merge all the cut parts back together.

How to, is here.
https://forum.selur.net/Thread-INFO-MKV-Cutter-tool-to-cut-h-264-mkv-files-frame-accurate

[Ennio]

Maybe you can also try in avidemux. It can recode-only the necessary frames at the cutting points, should they not be keyframes.

[may5224]

Maybe you can also try in avidemux. It can recode-only the necessary frames at the cutting points, should they not be keyframes.

Hi, thank you for your reply. I did test this program but it did not work for me. Maybe I am doing something wrong so I will tell you how I've tried to do it.

I took these steps:

1. Open and select the file you want to split (File / Open).
2. Then, with the bar below, select the point where we want to start our video and clicking on the letter A using icon ( or press [ ) and mark point B ( or press ] ) where you want to end (cut) your video.
3. Finally from the menu select File / Save / Save Video

It does cut the video, but still with inaccurately. Do you have any other suggestions or did I do something wrong?

Thanks either way!

EDIT: I did change the "Video Output" option at the left-corner from "copy" to "MPEG 4 AVC", just for testing purposes. And this time it worked. But the issue now is that it is encoding the entire video. That's not really what I am looking for. Can I do it in another way using this program? I think that this program has the potential to solve my issue but I don't know how yet.

[may5224]

https://www.videohelp.com/software/MKV-Cutter

Has to be h264, so might not be suitable for your case.
The "cutter' part refers to the part that is to be saved (select Start Cut and End Cut).
Only the cut point is re-encoded.
I've used this to cut up an mkv file that was out of sync in one section, so that I could re-sync the part then merge all the cut parts back together.

How to, is here.
https://forum.selur.net/Thread-INFO-MKV-Cutter-tool-to-cut-h-264-mkv-files-frame-accurate

Hi, thanks for your reply.

I did try this tool. But it did not work for me, unfortunately.
Whenever I try to load the MKV video it gives me the error: "No keyframes found (C:\\directory\dummy\dummy\name.mkv)" <-- dummy directory example

The codec info of the video I am trying to cut is: H264 - MPEG-4 AVC (part 10) (avc1)
I Google'd the error and couldn't really find anything. Do you have any suggestions or things you notice that cause this issue?

Thanks again!

[may5224]

Lossless cutters can only cut on keframes. Keyframes may be several seconds apart.

https://en.wikipedia.org/wiki/Group_of_pictures

Players can seek to any frame but often have a setting that lets it seek to the nearest keyframe (because decoding is faster that way).

I see, thank you for your reply. So to put the question as simple as possible; is there a way that I can cut off the first 20-seconds a video precisely without having to reencode the entire MKV video using a program?

I already tried:
- MKVMerge
- Lossless Cutter
- MKV Cutter
- AviDemux <-- (works, sort of, but uses encoding to achieve results instead of copying exists video values.)

Thanks either way!

[poisondeathray]

You'd have to use a smart renderer eg. videoredo, tmpgenc smart renderer, solveigmm video splitter

They don't re-encode the entire video, only the frames in the affected section are re-encoded up to the nearest IDR keyframe. The rest of the video is passed through untouched (stream copy)

But in theory, you can have a video with 1 keyframe (infinite) with open GOP's . This means essentially the entire video would have to be re-encoded because you have no other keyframes. The problem with that is the way the video is encoded

[may5224]

You'd have to use a smart renderer eg. videoredo, tmpgenc smart renderer, solveigmm video splitter

They don't re-encode the entire video, only the frames in the affected section are re-encoded up to the nearest IDR keyframe. The rest of the video is passed through untouched (stream copy)

But in theory, you can have a video with 1 keyframe (infinite) with open GOP's . This means essentially the entire video would have to be re-encoded because you have no other keyframes. The problem with that is the way the video is encoded

Hi, thanks for your reply.

The first option works, I didn't try the others because the first one already did the job. But. Is there a free alternative? I don't mind paying for software but I won't be using it a lot. Just every once in a while. For example now, to remove a 20-second intro. Checked the others out too but all are "shareware".

Because of your post, it was clear that it is not possible to cut a video precisely with lossless quality.
LINK 1: https://forum.videohelp.com/threads/345340-Cutting-video-sections-with-Virtualdub-with...-recompressing
LINK 2: https://avidemux.org/smif/index.php?topic=18144.0
(There were some more but couldn't find them anymore.)

If you have any free suggestions left, let me know.

Thanks for all your help until so far.