Video takes over 10 hours to render!

Hi, I’m new to shotcut, and I’m created a video that’s about an hour long. After I was done with it, I left it to render at 7pm and let it render through the night, when I woke up at 6am, the rendering was still at 9%! I look at htop(I’m on Linux, htop is like Task Manager) and saw that Shotcut was still doing /usr/bin/melt -verbose -progress2 -abort <filename>! From my knowledge, that’s only the first stage of rendering! It didn’t even get to do ffmpeg, after more than 10 hours of running! Now, I expect the rendering to take a while, after all, I’m on a Thinkpad T480(Intel core i5-8250U processor), however I don’t expect it to take THAT long… For reference, I edited a 33 minute minute video earlier and it only took about 2 hours to render.
I didn’t do any complex edits, mostly just added text to my video because I made a lot of mistakes when I was recording my video… Here’s the contents of my Shotcut.mlt file as a reference: (I got this from the /tmp/ folder, as a Shotcut. file. Didn’t realize that a .mlt file was just an xml file). I also added the audio normalizing(two pass) filter, so I’m not sure if that’s what’s causing it to take a really long time. Thank you so mcuh for your help!

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That is wrong: melt is using FFmpeg libraries, and there is no second stage using ffmpeg directly.

added text to my video

That adds a lot of processing because images must be composited (text image on top of video image). It will probably go faster if you go to Export > Advanced > Video and enable Parallel Processing before starting the export. It is off by default because there is a small risk it will create some problems in the video output.


Thank you! I’ll try that!

Sorry for bothering you again, but I decided to give up rendering the hour long video(Sunk costs fallacy, didn’t want to waste time rendering something that could take forever on my computer). I tried to reduce the amount of text(limiting it to 3 texts) used in my video, but melt still takes a really long time to run(however, the processes its running isn’t very intensive). After letting it render for about an hour, it was still stuck at 1%. I am curious about what types of editing I should avoid in longer videos, so that in the future I can avoid adding things to my video that will take forever to run. Thank you so much!

This is a curious problem. I haven’t seen simple text filters cause that much slowdown, even on a laptop. What are the source video formats and what is the export format? And is there any chance RAM is insufficient and a lot of time is spent in a swap file?

Let me clarify a little bit, the editing that I tried to do was:

  1. Add a 20 min clip(with a text filter in the beginning) - file format mkv
  2. Because the 20 min clip’s audio wasn’t great, I fixed the audio in audacity(background noise reduction) and tried to merge the the audio in shotcut - audio file, wav
  3. Append a 40 min clip - also mkv
  4. Add a bunch of text filters to that 40 min clip!
    I only have 8GBs of RAM but I checked a screenshot I did while the video was rendering, and saw that melt + shotcut was using only about 7.5 GBs of RAM(I have 8GBs of RAM total) and none of my swap was used.

I tried to just do the first two steps of my editing using Shotcut(with no text filters, and only the audio normalizing filter, I believe) and the progress was stuck at 0% for an hour, and after about one and a half(or two) hours it finally got to 1%. I’m not sure why this is, because I’ve edited two(around 30 minutes each) videos with shotcut earlier and the rendering only took about 1-2 hours each. Just as extra information, I installed Shotcut on Arch Linux using the AUR(maybe it’s an issue with dependencies or something, I looked at the logs and saw that some libraries were not found, but since I rendered two videos just fine, I ignored it).

In the end, I gave up on using Shotcut(for the time being) and just used the ffmpeg command line tool instead because most of my editing is not too complex(aside from adding text filters). So far, doing the first two parts of my editing(fixing the audio of the first clip) that only took a couple of minutes with ffmpeg. Using just the command-line tools seems to work a lot better for me because of my limited needs(for video editing) and the relatively low specs on my computer. I’m not sure why the rendering took absurdly long. Anyways, thank you(again) for responding! Have a great day!

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