[FFmpeg-user] Bug in FFMPEG Alsa?

christina zou zou.christina at gmail.com
Sun Feb 19 12:18:41 EET 2017

Hi Nicolas,

> I suspect the difference might be related to the period time. FFmpeg
uses the lowest possible period time to allow low-latency uses, but it
makes for heavier CPU consumption.

I actually ran a test where I ran Arecord using FFMPEG's period_size and
buffer_size settings. Even when those settings are identical, FFMPEG still
takes 95% CPU and Arecord takes 5%.

You can see the full console results of this test in my FFMPEG bug file, if
you scroll to the 2 console output logs: https://trac.ffmpeg.org/ticket/6156

> For your next tests, I urge you to make sure no audio conversions
happens. You can do that with -c copy.

I also ran tests where I did 0 audio conversion in FFMPEG. Simply -c copy.
Incredibly, this still uses 95% CPU!


ffmpeg -loglevel debug -f alsa -acodec pcm_s32le -i mic_sv -c copy -f null -

Full console output: http://vpaste.net/N1U5b



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