Bug Report: Parallel processing doesn't seem to work if export resolution is different from video mode

Help/How To
1

Windows 10 Pro 64bit - 22H2
Shotcut version 22.11.25 64bit

When I just re-encode a video without changing the resolution then Shotcut uses nearly 100% of my CPU power either way, however I have a couple of 1080p videos here that I’m re-encoding and upscaling (lanczos) to 2160p. That job only uses like half my CPU power - but if I turn on parallel processing then it uses almost 100% again and thus is much faster - however this only works if I go to video mode and change it to 2160p as well.
So if I just set the export resolution to 2160p then I get like half CPU usage and it takes really long, if I go to video mode and set it to 2160p then it uses all my CPU power and is much faster - even tho the exported video is the same 2160p video in both cases.

2

Not a bug. When your export resolution or aspect ratio is different than your video mode, then it processes the timeline at video mode resolution using parallel processing but then it scales to export resolution on a single thread with multiple slices. It’s just different. I only recommend that you change the export resolution when you do not use Playlist or Timeline and instead use only the Source player with Automatic Video Mode.

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