There is probably a bit of a misunderstanding here, MKV is not a video format per say, its a container and allows multiple video and audio formats (the idea is to have one file which includes audio, video, subtitles, menus...). In another words, you can play one MKV just fine, but the other might fail simply because specific audio or video codecs is not supported https://en.wikipedia.org/wiki/Matroska
that said, I can confirm I cannot hear audio if the audio codecs is DTS format (my TV cannot decode it), I can hear the audio if it is AAC codecs
https://support.roku.com/hc/en-us/artic ... sic-photos"If you are playing audio that is Dolby Digital or DTS 5.1 Surround Sound, make sure your audio subsystem or TV can decode Dolby Digital or DTS."
