For a couple of years now, I've been able to import HEVC video into Vegas with no trouble. Occasionally I would need to re-wrap the video (ffmpeg -i "video.mkv" -c:v copy -c:a copy "output.mp4"), but it would always work.

Very recently, I got me some new video equipment. The only relevant one is the Atomos Ninja V+.

With it being a HDMI capture card at heart, I decided to run some tests with my computer's HDMI port and the HDMI feeds from a few of my cameras.

The format being used was the high (all-i) H.265 option. When recording video of my computer's HDMI output, the file just needs renamed from .MOV to .MP4 and it will load up fine (I can have a proper quicktime file from like 2006 and it will read fine if I rename to .MP4 so I get the feeling this software is just averse to the .MOV extension, but why just the extension, I have no idea). When I change the input to a feed from any of my cameras, renaming doesn't work. I figured maybe it just needs re-wrapped (like off my old capture card that uses the .mkv container for HEVC), but no dice. Sometimes I get the generic "undefined error" type error, sometimes it says the format is not supported, I get no useful information from the "show more" button in either case.

I'm using the exact same format that I used to record my computer screen, I'm editing these two different files on the exact same machine (11th gen i7, 16GB memory, RTX 3080, more storage than any sane person could shake a stick at expediently).

It would be nice if I could find out why this only happens with footage recorded from any of my camcorders' HDMI ports (all output 59.94p over HDMI so it's not some interlaced/progressive thing as I'm working with all progressive video, and again, the same encoding on the recorder), but even if I could find some way to force ffmpeg to encode all intra h.264 (as mentioned above, I have plenty of storage to do so, like, a half petabyte JBOD type box) and just work with that, that would be entirely sufficient.