[FFmpeg-user] Trying to understand ffmpeg cpu usage in this case of capturing rtsp streams

[Jim Ruxton]

Thanks so much for the help. Not sure why but when I try to upgrade ffmpeg
using the ppa as you suggested I get:

ffmpeg is already the newest version (7:4.4.2-0ubuntu0.22.04.1+esm5).

however if I check with "ffmpeg -version " I get :

ffmpeg version 4.4.2-0ubuntu0.22.04.1+esm5 Copyright (c) 2000-2021 the
FFmpeg developers
built with gcc 11 (Ubuntu 11.4.0-1ubuntu1~22.04)

There is no 7 showing up in the version number, though  maybe I already
have the newest version installed?


On Thu, Nov 7, 2024 at 6:37 PM Ferdi Scholten <ferdi at sttc-nlp.nl> wrote:

> I'm using Ubuntu 22.04 and ffmpeg version 4.4.2-0
> > I'm capturing 3 rtsp streams as shown at the bottom .
> > Stream A resolution is 1600x1200
> > Stream B and Stream C resolution is 384x192 .
> > Stream A and B are coming from one device (ip address) and Stream C is
> > coming from a second device (ip address)
> >
> > When I start Stream A and capture it with the command below I get a cpu
> > usage of around 90% using the top command. If I then start stream B
> > simultaneously it shows about 25% cpu usage in another ffmpeg instance.
> >
> > Then with the other 2 streams running I start Stream C and it shows about
> > 90% cpu usage.
> >
> > If I start Stream B on it's own it shows 90% cpu usage.
> >
> > In other words it doesn't seem to matter what the resolution of the video
> > coming in is but rather which stream starts first that determines the cpu
> > usage. Does it matter that Stream A an B are coming from the same ip
> > address and that explains why the second stream uses less cpu? My
> > expectation is that Stream B and C would have the same cpu usage since
> they
> > are the same resolution just coming from different devices.  Can anyone
> > explain what I see as strange behaviour. Stream commands follow.
> >
> >
> > Stream A: ffmpeg -f rtsp -irtsp://192.168.35.243:8086/?camera=world  -f
> > v4l2 /dev/video2
> >
> > Stream B: ffmpeg -f rtsp -irtsp://192.168.35.243:8086/?camera=eyes  -vf
> > format=yuv420p  -f v4l2 /dev/video3
> >
> > Stream C: ffmpeg -f rtsp -irtsp://192.168.35.247:8086/?camera=eyes  -vf
> > format=yuv420p  -f v4l2 /dev/video5
> >
> > Thanks,
> > Jim
> > _______________________________________________
> >
> Does this also happen if you use a less antique version of ffmpeg?
> Either a static build or build it from git master or use a ppa? were at
> version 7.1 now.
> Current versions are much better in using multiple threads and there
> have been numerous changes to internal code to improve the resource usage.
>
> for ease of use this ppa delivers ffmpeg 7.1 for ubuntu 22.04
> https://ubuntuhandbook.org/index.php/2024/04/ffmpeg-7-0-ppa-ubuntu/
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