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X264 max CPU usage? - Bartoloni - 12.04.2024

currently i replaced my 3700x with a 3900x (from 16threads to 24threads) to speed up Hybrid jobs...
is see this thread about x265.. : https://forum.selur.net/thread-3269.html?highlight=cpu+usage
and on videohelp this:

[Image: 3.png]


right now Hybrid is taking 80/88 % of cpu during a Temporaldegrain2 + deinterlacing


[Image: 1.png]


and i have tried with 17 threads or 0 ... but without any luck


[Image: 2.png]


there is a way to increase CPU usage or 17 is a fisical (software) limit of X264?

very thnak you for any help.

RE: X264 max CPU usage? - Selur - 12.04.2024

of cpu during a Temporaldegrain2 + deinterlacing
both are rather slow and have parts in them that can't really be multihtreaded that good and might cause a bottleneck

Quote:there is a way to increase CPU usage or 17 is a fisical (software) limit of X264?
iirc.
there is no real thread limit in x264, but depending on:
  • speed the hybrid encoder can acces
  • resolution of the input
  • number of threads (= encoding threads), lookahead-threads, rc-lookahead, sync-lookahead, sliced-threads
(for details you would have to look at https://code.videolan.org/videolan/x264/-/blob/master/encoder/encoder.c)
there is a limit on how much threads acctually can be utilized, also keep in mind that high number of threads can decrease the accuracy of the results an inter-thread communication might slow down the process too. (so higher cpu utilization, does not have to mean higher speed)

Also faster presets will also limit the effective cpu usage since they are streamlined to be fast and efficient an not unecessarily use ressources that are not needed.

maybe not the best analogy, but maybe it helps:
If you have 6 fast cars and you want to transport a sixpack of beer through a tunnel, you could split the bottles to each of your cars and thus increasing the utilization of the ressources, but using one car (which can hold the 6 bottles) is more efficient. (also when you can't drive all cars in parallel through the tunnel bottlenecks might occur)


Cu Selur

RE: X264 max CPU usage? - Bartoloni - 13.04.2024

(12.04.2024, 23:09)Selur Wrote: If you have 6 fast cars and you want to transport a sixpack of beer through a tunnel, you could split the bottles to each of your cars and thus increasing the utilization of the ressources, but using one car (which can hold the 6 bottles) is more efficient. (also when you can't drive all cars in parallel through the tunnel bottlenecks might occur)

this is a very interesting example.. i will take this for my customers Smile

very thank you for the infos Selur, and have a nice weekend.