Adding LUT makes preview 75% speed


first off i just want to say i love what is being done with ShotCut, it’s awesome!

So, i downloaded a few LUT’s from and whenever i apply one to a clip the preview plays in 75% speed.

Can someone else try these and see if you encounter the same issue or if it’s just me?


Works fine for me.
Bug reports need a lot more information.

Cool, then it’s just me! I’ll collect all the details later and submit here to see if there is anything apparent that is causing this behaviour!


Same issue happens to me under certain circumstances. If the video clip and the timeline/project resolution are the same, I get no stutter or speed change, and the CPU usage due to the LUT effect goes up only 2%. But if the video clip and the timeline are different resolutions, the video slows to 75%, the audio stutters, CPU usage goes up 13%, but overall CPU is only 25% and no single core is at 100%.

This even happens if the timeline resolution is 1080p 29.97fps and my video clips are 360p 29.97fps proxies. Playback without the LUT is flawless and uses only 11% CPU. If I change the timeline to 360p, playback with the LUT is flawless too. On a 1080p timeline… no go.

I echo that Shotcut is awesome and 19.02.28 has been very stable for me.

Windows 7, Shotcut 19.02.28, 16 cores, 16 GB RAM.

This is normal and not a bug. All filters require processing power. It is not able to consume all your CPU due to lack of full optimization. Again, not a bug. It’s just the way it is in preview.

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