[FFmpeg-user] Best place for despill filter?

[Michael Koch]

Am 16.11.2020 um 16:12 schrieb Paul B Mahol:
> On Mon, Nov 16, 2020 at 12:41 PM Michael Koch <astroelectronic at t-online.de>
> wrote:
>
>> Am 16.11.2020 um 12:22 schrieb Paul B Mahol:
>>> On Mon, Nov 16, 2020 at 12:13 PM Michael Koch <
>> astroelectronic at t-online.de>
>>> wrote:
>>>
>>>> When I overlay a bluescreen foreground video over a background video,
>>>> which is the best place for the despill filter? (a) before colorkey or
>>>> (b) after colorkey or (c) after overlay?
>>>>
>>>> [foreground](a),colorkey,(b)[fg];[background][fg]overlay,(c)
>>>>
>>>> I found here an example for (c) but I doubt that this makes sense:
>>>> https://gist.github.com/kerbeh/fbe0cd0d89c424708c119e0a0d00ca88
>>>>
>>>>
>>> Why do you doubt that it does make sense?
>> I doubt that (c) is the right place because at position (c) the despill
>> filter also affects the background video, which surely doesn't have any
>> contamination from the bluescreen.
>>
> Then use it after colorkey.

Is it possible to send zmq messages to the despill filter? I want to 
adjust the mix, expand and brightness parameters in real time. I'm 
sending the zmq messages from my own C# program. Messages to colorkey 
(color, similarity) and overlay (x, y) are already working. When I send 
messages to the despill filter, there is no error message but nothing 
changes in the output video. Either I have something wrong in my code, 
or the despill filter doesn't use the new values.

Michael