Many high-end MKV files use "lossless" audio like Dolby TrueHD or DTS-HD MA, which Roku does not support natively. These files will either have no sound or will require an external A/V receiver capable of decoding the passed-through audio signal. Method 1: Playing MKV via USB

Roku devices natively support playing files, but success depends entirely on the specific video and audio codecs inside that MKV "container". While the MKV format itself is compatible, your Roku may fail to play it or play it without sound if the internal encoding doesn't match Roku’s official specifications. Supported Codecs for MKV Playback

AAC, AC3 (Dolby Digital), EAC3 (Dolby Digital Plus), DTS (pass-through only), MP3, FLAC, and PCM.

: Ensure your subtitle file (usually .srt or .vtt ) has the exact same name as your MKV file and is stored in the same folder.

If the Roku Media Player won't play your file or display subtitles, consider these options: Enable Subtitles(closed Captioning) on Roku TV