Hi, I was wandering if there is a way to route only alpha channel of specific layer to another one.
My case is:
I have html template for L3 and want to use it to mask blurred live-in to create a sort of frost effect.
I’ve already tried to use ffmpeg filter vf extractplanes=a, but this only works for video (image,live-in) layers but not for routed nor html layers.
I mention that in first post, ffmpeg filters do not work on routed layers 
f.e. play 1-10 route://2-99 vf extractplanes=a
routes only layer without effect
That sounds to mem that you get some blurred picture as an input and want to use a mask for it. Maybe you need to post a picture on how it should look in the end.
Have you considered to input the video in the html and then apply the filters?
nice idea, I need to test this one. I am bit worried about delay.
The only downside of this solution is that this input will have no other use because it will be reserved in html template.
I use a web presenter for that, so it is just a usb port instead of a thunderbolt or a pcie.
I guess the delay is mostly due to the hardware, in my case seems to be very little, in order to 100~200ms, but I haven’t measured.
It takes a bit longer to initialise though.
It works also with NDI virtual camera, so you don’t have to waste an input and route a channel to it, but then the delay will be significantly more.