[FFmpeg-user] ffmpeg/libx264 thread management

Tim Nicholson tim.nicholson at bbc.co.uk
Tue Feb 7 13:15:35 CET 2012

I have noticed that when ffmpeg is allowed to do its own thing and 
create subthreads it creates those subthreads with a nice value of 0, as 
per the master thread. However if performing a libx264 encode, these 
threads are niced up to 10. This means I end up with lots of threads but 
still no maxed out CPU. I can run 2nd and 3rd transcodes and each one 
runs at the same speed as the first to max out the cpu, but how can I 
max out the CPU for just the one?

Manually upping the thread count just increases the kernel cpu load as 
it tries to manage all the threads without increasing throughput...

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