How to implement fast encoding with ffmpeg?

Question

I want to know that how can I implement fast encoding with ffmpeg. I used this code:

vcodec libx264 -pix_fmt yuv420p -r 30 -g 60 -b:v 1000k -shortest -acodec libmp3lame -b:a 128k -ar 44100 -threads 0 -preset veryfast

But it only uses 50% CPU(dual xeon 2.3 ghz) and 2% (15gb) Ram.

Now I want it to use a lot of cpu and ram for fast encoding, how to do? Thanks everyone

What is the source video for this encoding and where does is come from? — user7860670, Jul 29 '17 at 13:59
Make sure the output doesn't show `using cpu capabilities: none!`. This indicates a misconfigured x264 and slower encoding. — llogan, Jul 30 '17 at 01:11

score 2 · Answer 1 · answered Jul 29 '17 at 11:40

2

How many threads are being used, highly depends on used codec, settings and hardware. Besides that, RAM is used rarely that amount by "just" 1000k bitrate with a small resolution. So you might never need about 15G of RAM.

In your case, you're setting -threads 0 which means "optimal usage" of hardware (will be set automatically by some algorithms). I do not recommend it, but you can try setting -threads 2 for 2 threads, or -threads 4 for 4 threads. As a rule of thumb, you can set one thread per core (if you have 4 cores, use 4 threads, 8 cores - 8 threads, and so on).

Please be aware, that simultaneously encoding video at all cores and audio might result in lower speed, than another "optimal usage" calculated by ffmpeg itself. Just give it a try ;-)

answered Jul 29 '17 at 11:40

Michael Hirschler

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Thanks for the help, i have tried increasing to '-threads 8' but encoding speed has not changed – prodiskieu Jul 29 '17 at 15:17
Okay, maybe the preset defines ``-threads`` too. Try setting ``-preset veryfast -threads 2`` (notice, ``-preset`` comes first, so ``-threads`` will override). – Michael Hirschler Jul 29 '17 at 18:02
Thank you very much, but it's speed of encoding is still constant. I give up: v – prodiskieu Jul 30 '17 at 06:16

How to implement fast encoding with ffmpeg?

1 Answers1