[FFmpeg-devel] is it possible that avfilter graph updates its setting in realtime?

Moritz Barsnick barsnick at gmx.net
Wed Oct 26 00:50:08 EEST 2016

On Tue, Oct 25, 2016 at 14:24:34 +0800, qw wrote:
> I have one question about some rare usage for avfilter graph:

Wrong list for usage.

> Sometimes, I want to change the setting in avfilter graph. For
> example, fps filter is used to set output frame rate, and it's
> expected that fps can be changed in accordance to real needs.
> Sometimes, fps is set to 25, and later 15 as network bandwidth is not
> good. Is it possible that avfilter graph updates its setting in
> realtime, such as fps in fps filter, and widthxheight in scale
> filter?

Have a look at the zmq filter. I gave an example here:

It seems it doesn't actually work for the fps filter (patch perhaps

Good luck,

P.S.: Syntax for two parameters: Something like
      echo 'Parsed_scale_1 width 600 height 400' | tools/zmqsend
P.P.S.: I recall some patch for actually changing the filter *graph*
      (i.e. chain(s)) during runtime, don't know where, or what

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