[Feat request] Speed up scene detection for very high res content (4K and above) about av1ador HOT 4 CLOSED

I tested the scene detection with a 4k hdr source and the same but downscaled to 720, the speed was 1.33x vs 1.32x. I knew the bottleneck is the cpu decoding speed.
A possibility is to use the gpu to decode, but in my experience this is unreliable, it fails with some encodes and the gpu variations decode different formats.
But, I still can speed up the detection using more than one process, on my pc the decoding use 25% or less cpu, so at least we can use three processes. I'll do it when I have time because I need to change the worst code in the program xd

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Just for context I ran a quick test on my system (Ryzen 5950x w/ 64GB RAM) and this is how long it took to detect the scenes:

Video 1 (4K, 2h12m): 15min
Video 2 (1080p, 1h47m): 4min

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Haha, ok mate, no problem. Thanks a lot! Any way I can help? I can try to investigate the command line for ffmpeg to add more threads if you point me to the place in the code where it's used.

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Haha, ok mate, no problem. Thanks a lot! Any way I can help? I can try to investigate the command line for ffmpeg to add more threads if you point me to the place in the code where it's used.

Sure but I think ffmpeg doesn't have that option.
I added multhreading to the scene detection when the video is large, with a maximun 3 ffmpeg processes, check if this helps

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