Not using ffmpeg & VAAPI worked for me. Maybe the ffmpeg in Linux Mint has issues. Or maybe VAAPI with an AMDGPU, doesn’t make good videos. I added the tag the internet claims will make it work.
Sound and no video in the photos app is all I got.
I tainted Linux Mint, by installing the Pro AMD driver. And converted a video with HandBrake using the GPU, and it plays. Before, I just used the shitty Insta360 Studio app using Wine. That played too. So software encoding works as well.
100 FPS less with HandBrake then ffmpeg. Probably cause it’s using CPU to decode.
Also, if installing the Pro driver doesn’t make it work, you need to update linux-firmware as well. I just backed up the amdgpu in the firmware folder, and then copied the new files over.
And don’t download the latest version if using a AMD 6000 series.
Version 6.4.4 amdgpu-install worked for me. Somewhere on AMD’s GitHub somebody said to use that version. No more AMF encoding, with newer AMD Pro drivers in Linux, if using an older GPU.
Good news, I’m too cheap to buy a new GPU.