Playback Issues - Audio/Video & Power

Help with audio & video playback issues, TV display type recognition & compatibility, HDCP messages, troubleshooting playback errors, advertisements, and resolving power issues.
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byteme_
Level 7

Matroska files do not play sound

I'm having big issues with my Roku Ultra: it refuses to play sound from .mkv files. Menu sound works & .mp4 files do play sound. I already have reset the device to factory default, but the problem remains. I also tried to manually set the sound to stereo and the HDMI output to PCM-stereo as found on internet as a solution. But it doesn't work. It's not a stereo/surround issue. Files with AC3 2.0 audio do not work, same as files that contain DD/Atmos/etc. The files are on a external HD which i connect directly to the device...

Model: 4660X Roku Ultra
Version: 9.1.0 4111-46
S/n: YJ0007728661
Connected through wifi
TV is Full HD

Help would be appreciated, i'm this close to literally throwing it back to the states :twisted:
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3 Replies
blade_005
Level 10

Re: Matroska files do not play sound

"byteme_" wrote:
I'm having big issues with my Roku Ultra: it refuses to play sound from .mkv files. Menu sound works & .mp4 files do play sound. I already have reset the device to factory default, but the problem remains. I also tried to manually set the sound to stereo and the HDMI output to PCM-stereo as found on internet as a solution. But it doesn't work. It's not a stereo/surround issue. Files with AC 2.0 audio do not work, same as files that contain DD/Atmos/etc. The files are on a external HD which i connect directly to the device...

Model: 4660X Roku Ultra
Version: 9.1.0 4111-46

Help would be appreciated, i'm this close to literally throwing it back to the states :twisted:

Most HDTVs cannot decode AC3 or DTS over HDMI directly. If your MKV files contain AC3 or DTS audio, Roku may fail to play the audio. If your Roku Ultra is connected directly to your HDTV without going through a Audio Receiver or Soundbar that can decode Dolby Audio (AC3, DTS) then you will not hear any audio. You either must pass the audio through a device that can decode or convert the AC3 audio to AAC and then it will play audio directly connected to HDTV.
TCL-TV Roku 55P605 (4K HDR & DV) | VIZIO SmartCast SB3651‑E6 Soundbar
TCL-TV Roku 43S425 (4K HDR) | TCL-TV Roku 32S301 (720p)
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atc98092
Level 13

Re: Matroska files do not play sound

If it's truly Dolby Digital/AC3 audio, it should be working. But if it's DD+, DTS, or any of the lossless codecs, few if any TVs support those audio codecs. And as mentioned, external sources (such as a Roku) are completely dependent on the TV being able to process the audio. Setting the audio to PCM will only work if the audio is two channel stereo, as the 4660 does not contain an encoder to convert multi-channel audio. Here is the official support page:

Many Roku players can decode Dolby Digital™ (AC3) audio. Some can also decode Dolby Digital Plus™ (E-AC3), but others cannot decode either. If you are trying to play Dolby Audio™ (AC3, E-AC3), but do not hear multi-channel surround sound, try connecting your Roku player via HDMI® or S/PDIF (optical) to a TV or A/V receiver capable of decoding Dolby Audio™. Your Roku player will pass-through the encoded Dolby Audio to the TV or A/V receiver for decoding.

Some Roku players can decode Dolby Digital Plus to HDMI and S/PDIF TOSLINK (optical). This means that content encoded with Dolby Digital Plus will be transcoded (converted) into Dolby Digital if your A/V receiver does not support Dolby Digital Plus, but does support Dolby Digital 5.1.

Now, your 4660 does not have an optical out, so you don't have that option. But in general, if you want your multi-channel audio, your best bet is to connect your Roku via HDMI to an AVR or sound bar that supports AC3, E-AC3 and DTS. If you go with a sound bar, be sure to check that it supports all of those codecs. For AVRs, I don't think you can buy a new one nowadays that doesn't support them all. 
Dan
Nvidia Shield, Roku Stick (3600), Ultra (4640), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.
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byteme_
Level 7

Re: Matroska files do not play sound

Thanks for the replies. It was definitely the television which couldn't handle the 5.1 sound. I got a new television where I can select DTS option. I've selected DTS in Roku and now the sound works in the videos (even though I just have stereo speakers).
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