expected performance for software encoding

[realies]

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after weeks of fighting with amd 9950x igpu passthrough to a windows vm, and the never ending amd gpu reset issues that make it impossible to use the igpu if the vm restarts or shuts down without power cycling the host first, i decided to give sunshine software encoding a try

unfortunately, i'm getting about 7-30fps on 1080p with the fastest ffmpeg presets and moonlight set to either 60 or 120fps

is this expected? the 16 threads dedicated to this vm are barely using 2% of the cpu, is there something else that could be the bottleneck?

[ReenigneArcher]

Software encoding is slow and will never come close to gpu encoding. You might need to lower the resolution a little more.

[realies]

is this because ffmpeg can't encode in realtime?

[vjdw]

In Sunshine Advanced settings tab what have you got "Minimum CPU Thread Count" set to? Does it work any better if you lower the bitrate?

[realies]

I remember trying all presets and low/high bitrates. It felt there's a too big of a delay with all configurations. Not sure if relevant and haven't looked at the software encoding implementation but I think the default sw encoding buffers for FFmpeg have too big of an input buffer for this purpose.

[vjdw]

Yes, I think I have a similar problem to what you were seeing. I'm running moonlight at 1440p, 150mbps over ethernet. Sunshine is on a machine with 12C/24T. With software encoding when I set minimum thread count to 4 I get about 20fps. When I set it to 8 threads I get about 30 fps. When I set it to 12 I get about 35 fps. So it's a case of diminishing returns, and I don't really want to go beyond 12 threads just on video encoding.

AMF encoding on my 5700xt gives me a solid 60fps so I'll stick with that. I think in theory software encoding can give a better picture quality than hardware encoding, but that's no good if I'm only going to get 30fps!

[ReenigneArcher]

Performance can probably improve greatly by lowering the resolution and bitrate. Software (CPU) encoding is just a lot slower than GPU encoding, so anything you can to do to make it easier on the CPU will help. Software encoding will never be close to the performance you get with GPU encoding though.