Add support for ffv1 versions 1, 2 and 4

[sdroege]

Currently only v3 with microversion >1 (probably actually == 1?) is supported.

When using ffmpeg for encoding, it needs a bit of trying to actually end up with version 3

[lu-zero]

I guess extending it to support version 4 should be the easy path forward.

[sdroege]

Yeah but ffmpeg gives you version 1 by default if it can :)