I use MKV files to store Movies. HD and 4k versions with many different types of encoding. I have recently added a Streambar Pro to my device pool. Some very recent files have shown to work smashingly on my Roku Ultra and and unwatchable on my brand new Soundbar Pro. Incorrect frame sizing, noise on the side of screen, grainy lines in the middle. I tried to use other copies of files and sometimes it works, sometimes not.
Is the Streambar Pro a poorer version one the Roku Media Player? Is the OS comparable to the Ultra? Is it a different OS? Should I not have messed with fate and skipped the sound bar experience?
The Streambar devices do use a different processor than the latest players. I can't say if that's a good or bad thing, as I've never tried using any version of Streambar. But the OS is basically the same, and should only differ for hardware differences. But the hardware does differ quite a bit compared to the latest Ultra or Express 4K+.
I do have to say that Roku hasn't made any noticeable updates to Roku Media Player (the video player app) in more than three years. It has many "quirks" (to be polite about it) with video playback, but my experience with MKV files are usually good. But video and audio codec differences in your files might explain why they play well on one device but not another. Remember that the MKV is merely a container, and the objects within that container can vary significantly. Something as simple as the compression level of an H.264 video might cause a problem.
1 week and still can not get the video playback function as it should, watching the same advertisements 2x at each break sucks!