Partial Remux

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iamgap

New Member
Sorry if this has been asked and answered, but not finding the correct query to get results.

First, praise to whomever engineered the remux tool. I have yet to find another encoder that can make the same quality video with approximately the same file size.

I would love to have the ability to add a start and stop point when remuxing a MKV file. Currently I am using Premier Pro to edit or grab the middle out of a recording, which pretty much quadruples the file size, even when taking less than half the original recording. I end up using the 'low bit-rate' option to get an acceptable file size.

In this forum I found a suggestion to install Handbrake, and it does a decent job, but still has a larger file size on a shorting video. It will be my go-to until (if) partial remux is an option.

I prefer not to set automatic split points, as then I would need to combine those together for the full recording.
 
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rockbottom

Active Member
YW!

That's the first stop & most of the time the last stop for my recordings. Pretty much only need to use my NLE for syncing external audio sources.
 
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iamgap

New Member
rockbottom said:
Use Avidemux for remuxing duties. Just make sure you're cutting on Keyframes or the file will get re-encoded instead of remuxed.
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This is great!! Thanks!!!

Took me a bit to figure out how to 'cutting on keyframes' (basically just use the Copy option), but it works wonderfully. It's a bit wonky getting to the keyframes I wanted (it wouldn't let me select a specific spot), but once I got close and removed the unwanted sections, it did what I wanted it to do.


gap
 
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rockbottom

Active Member
Previous/Next Keyframe navigation in red.
1709766884929.png
 
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rockbottom

Active Member
I record with my Keyframes set @ 1 second when using advanced mode, in the Custom Output, I set it @ half a second. This allows for much closer edits/cuts with Avidemux.
 
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Lawrence_SoCal

Active Member
iamgap said:
First, praise to whomever engineered the remux tool. I have yet to find another encoder that can make the same quality video with approximately the same file size.
Click to expand...
in part that is often (ex MKV to MP4) OBS Studio remux tool is NOT re-encoding... just swapping out the video wrapper (video itself is untouched)

The beauty of (and a key driver to use) Avidemux is that it also does NOT typically re-encode the video when simply trimming at correct framing point

Why might you have an issue not selecting the EXACT frame you want?
basics of video files... each video frame is not stored 'separately'. A full frame of video is stored occasionally (ex 1-2 seconds), then 'difference' (P- or B-)frames are saved in-between. So depending on a variety of factors, you won't be able to trim at one of the intermediate frames (as without re-encoding the frame, an intermediate frame is not really usable without all preceding frames back to I-frame)
 
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iamgap

New Member
Lawrence_SoCal said:
Why might you have an issue not selecting the EXACT frame you want?
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When I was saying frame, I was referring to the frames as seen in After Effects. Basically I like to cut a video at a spot that doesn't show a portion what I am cutting out.

As an example, we use OBS to stream and record our Sunday services. The Church just switched to Subsplash, so they want both the whole service and the Sermon only. I want to split it just before the Pastor starts the message, without capturing the previous song/instrumental. And then cut again at the end of his prayer without his calling everyone to stand and sing.

With Avidemux, I can now edit out the pre-service music and countdown that is recorded during the stream.


gap
 
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