This is what the Roku web page says it supports:
https://support.roku.com/hc/en-us/articles/208754908-Roku-Media-Player-Playing-your-personal-videos-music-photosWhat media file types does the Roku Media Player channel support?
The following media file formats are supported:
Video — H.264/AVC (.MKV, .MP4, .MOV), on Roku 4 only: H.265/HEVC (.MKV, .MP4, .MOV); VP9 (.MKV)
Audio – AAC (.MKV, .MP4, .MOV); MP3(.MP3, .MKV); WMA (.ASF, .WMA, .MKV), FLAC (.FLAC, .MKV), PCM (.WAV, .MKV, .MP4, .MOV), AC3/EAC3 (.MKV,.MP4. .MOV, .AC3), DTS (.MKV, .MP4, .MOV), ALAC (.MKV, .MP4, .MOV, .M4A)
Image — JPG, PNG, GIF (non-animated)
Only supported file types are shown in the Roku Media Player channel. The channel hides unsupported file types.
Multichannel AAC is not supported on all Roku models. Roku TV’s and Roku 4 set-top-boxes do support multichannel decode to PCM stereo.
On Roku set-top-boxes Dolby Digital audio (AC3, EAC3) is only supported via pass through.
DTS is only supported via pass through on both Roku set-top-boxes and Roku TV’s. You must connect your Roku player via HDMI or S/PDIF to a TV or receiver capable of decoding Dolby Digital or DTS in order to hear videos with audio tracks in those formats.
Some media server software may convert files into Roku compatible formats.
DRM-protected content is not supported.
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