[FFmpeg-user] Slowing ffmpeg down

Rich Andrews stuart.r.andrews at gmail.com
Wed Aug 12 04:01:14 EEST 2020

Is there any trick to slow down ffmpeg on a simple stream mapping?

Stream mapping:
  Stream #0:0 -> #0:0 (pcm_s16le (native) -> pcm_s16le (native))

Given an input file that is looped and output with a command such as:

ffmpeg-4.2.1-armhf-static/ffmpeg -y -t 200 -stream_loop -1 -i HoldMusic.wav
-map 0:a:0 -f wav output.wav

ffmpeg can move the data really quickly!

bitrate=1411.2kbits/s speed= 262x

Any way to get that speed down to ~1x?  My purpose is that ffmpeg is being
used as a child subprocess and I would like to be able to test its behavior
in-situ.  There is a lot of timing in my  application between fork and join
and having ffmpeg be slow would be really helpful.

Push comes to shove, I'll just use another program to more slowly copy, but
that wouldn't be as good as using ffmpeg itself since it has a host of
behaviors as a child process regarding signaling and return codes. Come to
think of it, since I built ffmpeg, maybe I can just build a variant that
sleeps frequently?

Thanks for any clever ideas!

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