Problems opening a ffv1 encoded file

Yes to all those :)

ffdshow does not support FFV1 v1.3 Someone really needs to create a new VFW wrapper for FFmpeg because ffdshow project is dead.

Does v1.3 kick in at some specific point (resolution perhaps?)

Well, yes - I'm going to encode the video with x264 so I'll use FFVideoSource for that since I need to do some filtering too. I am just puzzled why this one case refuses to open normally while others encoded with the exact same characteristics have no problems.

Afaik v1.3 is something you must explicitly specify during encoding. The file being v1.3 is just a guess based on the fact that other files did work with ffdshow.

I'm beginning to think that it has got something to do with the resolution of the encode, maybe ffmpeg switches the baseline without asking me.. I encoded a different clip, this time with a resolution of 928x720 and it also fails to load without any special tricks.