Vimu Media Player for TV 10.10 (Paid)

Key features:

One minute setup!
Optimized for the TV.
Support for most common file formats: MKV, AVI, MP4, MOV, FLV, TS, MPTS, WMV, DIVX, 3GP, VOB, MP3, FLAC, ALAC, JPEG (depends on device capabilities).
Hardware decoding up to 4k (HEVC/VP9) on Android TV for compatible devices.
Grid, list and double list navigation.
Works as UPnP Renderer (DLNA Push) on Android TV.
Simple and fast Leanback UI for Android TV.
Android TV Picture-in-Picture mode support (7.0+).
Navigation and playback from internal storage, SD cards and USB drives.
Navigation and playback from Windows shares (SMB).
Navigation, search and playback from UPnP/DLNA servers.
Navigation and playback from WebDAV servers.
Navigation and playback from NFS servers.
Switching audio tracks in multilingual files.
AC3, EAC3, DTS pass-through on Android TV.
Support for external SRT subtitles in any encoding (you need to have an srt (lower case extension) file in the same directory as your movie file like movie.mkv and movie.srt).
Support for embedded MKV, MP4 in SSA/ASS,, SRT, DVBSub and VOBSub formats
M3U playlists support.
Streaming (progressive download) from HTTP/HTTPS sources.

This app is ONLY compatible with TV boxes and TV-sets. Tablets and phones are not supported!

Documentation:
http://www.vimu.tv/

Official support forums:
Support Group: https://groups.google.com/group/gtvbox

If you have no sound while playback, your video file might have unsupported audio track.
If some of your files fail to play you can get refund for 3 days after purchase.

Apps is compatible with all official Android TV units.
App MAY BE compatible with some non-official TV Boxes based on Android 6.0 and higher.