[FFmpeg-user] -threads 1 seems not work

Cecil Westerhof Cecil at decebal.nl
Mon Sep 12 15:38:03 EEST 2022

Paul B Mahol <onemda at gmail.com> writes:

> On 9/12/22, Cecil Westerhof via ffmpeg-user <ffmpeg-user at ffmpeg.org> wrote:
>> 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)

Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof

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