My ordering costumer requested the format. But you're totally right handbrake didn't work because of the ProRes codec. I tried exporting it in H.264 and now it works like a charm...Thank you! Is this the best way to do quality-wise though?
I know I sound like a wiseguy now, but in case you come into contact with customers like this more often, you can shine by knowing:
An encoded video is defined by two things:
- A (video and audio) codec that determines the size and quality etc.
- A "container" that holds metadata and structures the (V and A) content
".mkv" is nothing but merely the container format (like .avi, .mpg or .mov) and most companies get that wrong. It was the same in your case: The container format ".mov" poses no problem to Handbrake, but the contained codec "ProRes" did.
If you are looking for the best possible quality in an mkv container, you have two main options:
- Export from editing program into (almost) lossless codec like ProRes and then encode and convert it to .mkv (with a smaller codec if size plays a role)
- Export from editing program into a codec with good compression (like H.264) and then only change the container to .mkv
There are certainly nice GUIs to handle both those options, but I don't know any off the top of my head (Compressor doesn't output .mkv, Handbrake can't bypass codecs and MakeMKV doesn't accept .mov files). The only thing I can think of is output in H.264 codec and then use the command line tool "ffmpeg" with these options:
ffmpeg -i Input.mov -acodec copy -vcodec copy Output.mkv
This will only change the container and copy the original video data. However, you need to install ffmpeg and be okay with using the Terminal.
But I think the quality won't suffer too badly if you just output in H.264 and then recode with Handbrake.

You can just try and see if you can spot a big difference.
Cheers,
Floh