Sometime when I was sleeping test encoding finished:
frame= 7045 fps=0.3 q=27.0 size= 42240KiB time=00:04:53.83 bitrate=1177.6kbits/s speed=0.0124x el[out#0/webm @ 0x8c273d0] video:38966KiB audio:3366KiB subtitle:0KiB other streams:0KiB global headers:0KiB muxing overhead: 0.390187%
frame= 7073 fps=0.3 q=21.0 Lsize= 42498KiB time=00:04:55.00 bitrate=1180.1kbits/s speed=0.0125x elapsed=6:33:50.16
yeah, 6 h 33 min 50 seconds for 4:55 clip (720p, 24 fps, 8 bpc, 4:2:0, vp9)
x265 was going at 0.7 fps but then Termux with ssh session without terminal software like screen was killed by memory pressure from Chrome here, so encoding not finished properly (but fps reading was quite consistent along whole vid for various codecs)
x264 was doing at 5.08 fps (video only) - altivec rule!
mpeg2video was zipping at 24 fps or even 26 if I set g=1
mjpeg/xvid both were slower at 17-14 fps.
asv1 was champion (for being simplest yuv420 only encoder) at 30 fps.
libaom-av1 failed to produce even single frame in minute, so I killed it.
on x86, x86-64 and arm64 situation is better due to SIMD acceleration, but you see the trend.
if av2 continued in this direction - we can set movie to encode and put it into time capsule with writing "open in year 2050" ;)