Kdenlive renders massive file sizes: how can I fix this?

I’ve made a screen recording with OBS that capped in at about 16 megs. I wanted to trim the ends of it (starting the recording, ending the recording), but didn’t know how to do that, so I just installed Kdenlive (which I’d been meaning to do anyways) and did it there. I selected the clip, hit Project, and rendered as per a short tutorial I found. The shorter clip ended up being a whopping 50 megs. How does this work? How can I ensure that a shorter video is, in fact, smaller? For context, the original recording was saved as an MKV, whereas the final render was an MPEG-4

Thank you in advance!

For such tasks I recommend ffmpeg CLI (see an example here or search for ffmpeg trim video).

Or, any of the GUI tools for ffmpeg that are out there.

One of the possible reasons for the increase in size is that OBS recorded using a variable frame rate. Kdenlive uses a fixed frame rate (e.g. 24 or 30). So it has to fill the gaps OBS left which, of course, requires more space.

BTW, MKV and MP4 are just containers or wrappers, not codecs (and codecs are responsible for the quality and size of the video).

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Just one of the tools that came highly recommended for simple trimming: GitHub - mifi/lossless-cut: The swiss army knife of lossless video/audio editing

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While I understand that there may be a more “optimal” tool out there, I was asking about this issue primarily with Kdenlive because I intend to use it as my go-to video editor, and I currently feel like the added friction of learning a second tool for “quick fixes” would be more trouble than it’s worth. Is there a setting I can adjust for Kdenlive to make it a little less resource-intense?

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You can get a smaller output by moving the “quality” and “encoder speed” slider to the left.

But as berndmj said, kdenlive isn’t best suited for this. You can use a dedicated video cutting program (search “linux video cutter”) or ffmpeg. They are much faster as they don’t do any re-encoding.

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Trying LosslessCut, it seems it’s very ill-suited for the job. It appears its whole deal is trimming w/o re-encoding, which requires cutting at key frames. When I’m trying to trim off the first second-and-a-half of footage, it just doesn’t cut at all - do you have any other software recs that might allow tight trimming, without massively increasing file size?

Have you tried the ffmpeg CLI option I posted above?

I understand that you prefer a tool with a nice GUI, but there may not be one out there …

i’m using loseless cut… it’s free and mutiplatform