Question / Help Quicktime and DaVinci Resolve do not read my mp4's, mkv's

[Akami_Channel]

The title says it all. What settings do I need to get MacOS to read my mp4's? I've been recording to mkv and remuxing to mp4. VLC will view them but nothing else. If I had a way to convert them I would do that, but even when I use ffmpeg to do a conversion, nothing changes. I'm not sure what MacOS is expecting of mp4's that I am not giving it.

 

[Narcogen]

If you try to open a remuxed mp4 in QuickTime player, what happens?

Are you using simple mode in OBS, or custom ffpmeg output?