Quote:
Originally Posted by benwaggoner
--pmode has a much bigger chance to be helpful, I'd say it's likely useful above 20 threads for 4K if using --frame-threads 1. The more modes being evaluated, the more parallelization for --pmode to take advantage of.
Using only a single frame thread can improve quality, but limits parallelization a lot, and combining it with --pmode can get some of that perf back if you have enough cores.
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Just for fun, I tested frame-threads from 5 (the default for my CPU) to 1 and then with pmode on my 5950X (16C/32T). The effect of pmode on the compression efficiency is much bigger than I anticipated. The speed increase was weird because my CPU usage is already around 90-100% when encoding with the default frame-threads and no pmode.
I ran this test on a 720p encode, normal setup and settings for my 1080p->720p encodes to the media library. I do use some uncommon parameters like --no-limit-modes and --rskip 0 which probably affect the results compared to standard presets.
I seriously need to test the 4K encodes as well.
F 5 - 5718.31 kbps - 7.11 fps
F 4 - 5713.13 kbps - 6.93 fps
F 3 - 5708.73 kbps - 6.74 fps
F 2 - 5715.94 kbps - 6.23 fps (odd that the size went up..)
F 1 - 5695.93 kbps - 4.50 fps
F 1 + pmode - 5490.78 kbps - 5.88 fps
F 2 + pmode - 5521.68 kbps - 7.43 fps
F 3 + pmode - 5515.12 kbps - 7.72 fps
F 4 + pmode - 5519.36 kbps - 7.83 fps
F 5 + pmode - 5521.10 kbps - 8.01 fps