Since I heard librav1e is kind of the fastest AV1 software encoder, I attempted to use it to convert an old MPEG-4 Visual video to AV1, but the result is way slower than the popular SVT-AV1 encoder. When I was using the default preset and a vbr of ~1200kbps of SVT-AV1 I can get an about 110 fps speed for that video, but when I use librav1e it barely exceeds 8fps, even with
--speed 10. Manually setting thread count or ramping up tiles does not work either. When I examine closely I see my CPU usage is normally 100% all the time with SVT-AV1, but with rav1e I only get about 30%~40% CPU Utilization.
I have confirmed that rav1e is using AVX2 by piping YUV output to a natively-built rav1e, both on Windows and Linux, so now I am quite puzzled by the situation: why does rav1e failed to pump out the full potential of my machine?
For a bit more context I am using a gaming laptop with 5800H CPU.