[FFmpeg-user] Need assistance finding l transcoding

Moritz Barsnick barsnick at gmx.net
Thu Dec 13 21:54:00 EET 2018

On Thu, Dec 13, 2018 at 18:33:02 +0000, James E. Baird wrote:
> I spun up a new server running Ubuntu 18.04.1 LTS and installed
> FFMPEG version which is the current supported version for
> Bionic Beaver.

Though I think that't not the issue, you should grab a much newer
version. You can get a pre-built binary here:
Please use the "git" version from the left hand side.

> Thanks for the suggestions so far. I suspect there is something in
> that command that is causing the high CPU usage. Maybe there is a
> better way to structure the command.

> %CPU 752.2 - %MEM 28.9 - 35:03.24 ffmpeg

Well, at least you seem to be utilizing your 8 CPUs almost as much as
possible, so it doesn't seem to be a threading issue.

> transcoder:~$ ffmpeg -i 'udp://@' -c:v libx264 -x264opts keyint=120:no-scenecut -b:v 6000k -profile:v high -c:a aac -f null /dev/null

Does it need to be fixed bitrate? (Just wondering.)

> frame= 2917 fps= 49 q=31.0 size=N/A time=00:00:48.91 bitrate=N/A speed=0.828x

Is this ultimately the issue? That you can't encode at real time?

At "constant"/average bitrate (-b:v), you should be able to use
libx264's presets to trade off quality for speed. Perhaps you can
achieve >1.0x that way. I don't see how you will do three simultaneous
encodes though.

BTW, eight CPUs to encode 1280x720 at 59.94 in realtime seems sort of
heavy. Are these Atom cores or something similarly weak?

> AMD Opteron(tm) Processor 6282 SE

Oh. Hmm.

> Thoughts?

Not many, sorry.


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