Suggestions for Smaller Filesize Without Losing Quality?

I REALLY like the way that Shotcut handles some of the editing workflow but I have an issue that restrains me from using it as primary editor.

I am wondering if there are any suggestions as to improving the rendered filesize without sacrificing quality. I used Shotcut for editing one of my videos from my YouTube channel and I noticed a very large difference in filesize when compared to Kdenlive.

Tested Video Duration: 10:07

I rendered the same video with both Shotcut and Kdenlive, here are the results.

Render Time:
Shotcut = 14:00 to 20:00 (depending on settings)
Kdenlive = 3:00 to 4:00

Filesize (First Run):
Shotcut = 226.7 MB
Kdenlive = 61.3 MB (baseline, only rendered once)

Filesize (Additional Run via Lower Quality Percentage):
Shotcut 50% = 168.1 MB
Shotcut 40% = 119.3 MB
Shotcut 30% = 80.7 MB

The quality drop is very significant with the 30% setting and it is still more in filesize than the Kdenlive version.

I also created an .mlt file and moved over flags from kdenlive to render with Shotcut but it doesn’t seem to improve the rendering.

Kdenlive and Shotcut both use MLT to process/render the videos so I am curious why there is such a significant difference in efficiency with render times, filesize and quality?

Any chance seeing the two results?
Also, what does Mediainfo report about both rendered files, can you compare?

Generally I’m happy with the files I edit with Shotcut not being large, they are certainly a lot smaller than the source .mov or .mts I typically import.

I am having same problem. To test, here is what i did:

  1. Recorded a screencast via sharex (size: 1.70mb)
  2. Imported in Shotcut
  3. Export with default settings (size: 5.5mb)

I’m using Shotcut version 18.01.02
Any suggestions?

add this to Export > H.264 High Profile > Other


and see if it gets better, it will be slower, but it should look alot better

Level depends on the resolution and frame rate. Better to not set this and let the codec automatically select it as it will not affect quality - just the correctness of signaling.


This is the important part to address the question.

I think one thing that most people overlook when trying to reduce size is the GOP setting. Shotcut uses a very low value per YouTube’s recommendation. The Hybrid tool mentioned in the linked thread is using 250 wtih 3 B-frames. Compare that with Shotcut’s default GOP of 13 frames with 2 B-frames.
Also, people are not comparing rate control modes. Shotcut defaults to quality-based VBR while the others are probably using ABR or bitrate-constrained VBR.

yeah levels, i set it to 4.1 mainly due to compatibility with hardware decoding but can be removed, also youtube will re encode regardless, also adding ref=9 & rescale=hyper will also improve quality

I use H.264 Main Profile and set
Tab Video is 1280x720
Tab Codec

  • Control Rate is Constrained VBR
  • Bitrate 512k
  • Buffer size 224.0 KB (default)
  • Quality 60% (default)
  • GOP 999 (max. because so high so good)
  • B frames 3 (default)
    my clip about 5 mins. from 48 MB it’s reduce to 11 MB.
    Try it.