x265/ffmpeg efficiency: Zen2 so much faster than Zen(1)+?

guru meditation

Recently I converted about 20 HD videos (1920x1080) with x265/ffmpeg to H265 (preset slow).

On a system with Threadripper (2950X) (Zen+, 16 cores, TDP 180W), it reached around 6 fps. CPU load was around 80-90%

On a Ryzen 3700X (Zen2, 8 cores, TDP 65W), it reached around 9-10 fps. CPU load was around 90%.

Both systems level out at around 4Ghz.

I tried to reduce ffmpeg to use only 8 cores and let 2 instances of ffmpeg run instead, but then I get 2 instances running at 3 fps.

Since the Gentoo is is basically the same: Is the Zen2 architecture so much advanced/optimised compared to the Zen+?

mike155 · Posted: Fri Jan 14, 2022 10:26 pm Post subject:

ffmpeg/x256 prints an info line with the hardware capabilities it uses. On my Zen3 processor, it prints:

Jaglover · Posted: Sat Jan 15, 2022 12:26 am Post subject:

I tortured my Intel CPU with it until nVidia cards got cheaper, I got a GeForce GTX 1660 when prices dropped. 1920x1080 encoding to H.265 goes average 190 FPS.

Edit: Just checked the prices, it was a few years ago, but I'm pretty sure I paid around $120 for my card. The prices are way up.
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guru meditation · Posted: Mon Jan 17, 2022 8:12 pm Post subject:

My ffmpeg shows the same CPU capabilities on both Zen2 and Zen+. 2 AVX2 units instead of 1 seems logical for the increased speed, as some other Linux' ffmpeg (without compiled in AVX supports) drags on forever.

H264/H265 GPU support is fine when you don't have to deal with low bitrates, then GPU encoding early tends to create block artefacts.I use nvidia to burn in timecode in a jiffy, but for movies x265 only.