[FFmpeg-user] Best place for despill filter?

Michael Koch astroelectronic at t-online.de
Wed Nov 18 16:48:28 EET 2020

Am 18.11.2020 um 14:40 schrieb Moritz Barsnick:
> On Mon, Nov 16, 2020 at 20:15:54 +0100, Michael Koch wrote:
>> Oh, what a pity. We need more filters with support for commands. Now
>> that I have found out how to send zmq commands from C# code, there are
>> so many nice things that could be done with FFmpeg in real time.
>> Especially when adjusting parameters that need visual feedback, for
>> example brightness, contrast, gamma, color corrections, colorkey
>> parameters, despill parameters and so on...
> Paul has worked heavily over the last few months to add command support
> to filters (and to properly document it). I guess it just isn't trivial
> in many cases, as the filters sometimes have not been designed with
> runtime reconfiguration in mind. (Any it may not be possible at all in
> certain cases.)

Yes, I know that Paul has added command support to many filters and I 
really appreciate this work!
Paul, is it possible to add command support also for the despill filter?
I'm asking because I've written a C# tool for bluescreening in real 
time. The foreground video comes from a camera via HDMI to USB converter 
(these cheap chinese converters are great!). The background comes from a 
file and is played in an endless loop. I have attached a screenshot. The 
color bars are the built-in test image from the HDMI to USB converter. 
All parameters can be adjusted with the scrollbars in real time and are 
sent to the FFmpeg process as zmq messages. It's already running fine. 
The only problem is that the despill parameters can't be updated in real 
time. They become effective after stopping and re-starting FFmpeg (which 
takes about 2 seconds).

If you want to see how this was programmed, have a look at chapter 2.56 
of my book:

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