This is an orange pi 5 without cooling. Perhaps it can’t reach the maximum because it has a thermal throttle? The CPU temperature is 42 ºC.
I’m using the same program in another computer and it uses more CPU and in a more consistent way. Without the lines being all over the place.
There could be a bunch of bottlenecks. Disk I/O to memory, memory I/O to the CPU, and the number of threads the program uses.
It appears that there’s a -threads option in ffmpeg you could set to 8.
One great tool for finding out if you’re being stalled by disk IO as well as other things is glances under Linux. If it’s an Io wait issue, you might be able to improve things by closing processes that are eating up memory, or by tuning swappiness or other memory parameters.
Yup, I agree.
It looks like ffmpeg is using about 1/3 of the processing power, but this is likely intentional, because if it froze your computer you’d be pissed.