[FFmpeg-user] -threads 1 seems not work
Paul B Mahol
onemda at gmail.com
Mon Sep 12 15:43:56 EEST 2022
On 9/12/22, Cecil Westerhof via ffmpeg-user <ffmpeg-user at ffmpeg.org> wrote:
> Paul B Mahol <onemda at gmail.com> writes:
>> On 9/12/22, Cecil Westerhof via ffmpeg-user <ffmpeg-user at ffmpeg.org>
>>> For a certain conversion I use '-threads 1'. As I understand it ffmpeg
>>> should then only use one CPU. I see that the CPU usage is lower as
>>> without this parameter, but it goes up to 180%. So clearly it is using
>>> at least two CPU's.
>>> Or am I understanding this parameter wrongly?
>>> I am using ffmpeg version 4.3.4-0+deb11u1. (Debian always lags a
>>> little bit behind to be more stable.)
>> threads can be used for input decoding, output encoding and filtering.
>> You need to use threads = 1 for all 3 of them.
> I see:
> But nothing for input decoding and output decoding.
> By the way: does this mean that ffmpeg can always use 4 CPU's?
> (input, output, filtering and complex filtering)
No, ffmpeg may use sometimes only 1 or sometimes all available CPUs.
That depends on many factors.
-threads is both input and output option.
> Cecil Westerhof
> Senior Software Engineer
> LinkedIn: http://www.linkedin.com/in/cecilwesterhof
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