[FFmpeg-user] How to scale FFmpeg

[Peter White]

First off, please do not top-post here.

On Fri, Mar 12, 2021 at 10:50:51AM +0200, imalkevich at gmail.com wrote:
> Hi,
> 
> Here are the three commands used:
> ffmpeg -threads 0 -loglevel repeat+level+verbose -f lavfi -i testsrc2=s=1920x1080:r=30 -f lavfi -i sine -c:a aac -ar 48000 -b:a 64k -c:v libx264 -crf 18 -preset medium -tune zerolatency -pix_fmt yuv420p -f mpegts - > NUL1
> ffmpeg -threads 0 -loglevel repeat+level+verbose -f lavfi -i testsrc2=s=1920x1080:r=30 -f lavfi -i sine -c:a aac -ar 48000 -b:a 64k -c:v libx264 -crf 18 -preset medium -tune zerolatency -pix_fmt yuv420p -f mpegts - > NUL2
> ffmpeg -threads 0 -loglevel repeat+level+verbose -f lavfi -i testsrc2=s=1920x1080:r=30 -f lavfi -i sine -c:a aac -ar 48000 -b:a 64k -c:v libx264 -crf 18 -preset medium -tune zerolatency -pix_fmt yuv420p -f mpegts - > NUL3
> 
> All the presets are 'medium' now.
> 
> And here are the outputs:
> [info] frame= 2222 fps= 25 q=17.0 size=  124402kB time=00:01:14.03 bitrate=13765.4kbits/s speed=0.835x
> [info] frame= 3441 fps= 19 q=18.0 size=  192778kB time=00:01:54.68 bitrate=13769.8kbits/s speed=0.631x
> [info] frame= 2632 fps= 17 q=18.0 size=  147456kB time=00:01:27.70 bitrate=13773.6kbits/s speed=0.582x
> 
> Thanks for the note about tee muxer, I read that it can send output to multiple locations, but in my particular example I'm trying leverage a case when I have multiple sources to be streamed to different locations.
> 
> The main question I have is - what if I want to stream to N different locations from one machine? If the quality of the output will be decreasing when each next process is starting, then it leaves me with running only one process on a machine?

You are using a rather resource hungry codec (x264), so the more
instances you run simultaneously the slower *all* of them get.

What are those sources you talk about? If they are already encoded
material then transcoding way be unnecessary and the copy codec, which
requires hardly any CPU power can be used.

Or do you want to stream *one* source to multiple outputs? If so, the
mentioned tee muxer can be used in a single instance of ffmpeg.

> -----Original Message-----
> From: ffmpeg-user <ffmpeg-user-bounces at ffmpeg.org> On Behalf Of Carl Eugen Hoyos
> Sent: Friday, March 12, 2021 9:59 AM
> To: FFmpeg user questions <ffmpeg-user at ffmpeg.org>
> Subject: Re: [FFmpeg-user] How to scale FFmpeg
> 
> 
> 
> > Am 12.03.2021 um 08:27 schrieb <imalkevich at gmail.com> <imalkevich at gmail.com>:
> > 
> > I'm trying to run the following command:
> 
> When asking questions on this mailing list, please do not attach screenshots of your console output, instead post the command line you tested (without using the hidebanner option!) together with the complete, uncut console output.
> 
> A few random comments:
> mpegts and mp4 are not the same things.
> You generally cannot request an FPS rate.
> When you use the x264 preset „slow“ do not expect it to work in real-time.
> There is a tee muxer and it is mentioned in the documentation.