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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radiocolin
Level 7

Roku + Vizio audio format issues

I have:

A brand new Vizio P55-F1 television
A Roku Ultra connected via HDMI
A Sonos Playbar+surrounds+sub connected to the Vizio by optical cable

On my previous TV - a Vizio E420i - I set the Roku into forced Dolby D+ mode, and the TV transcoded it down to Dolby Digital. I got proper surround sound out of all Roku apps - Plex, Netflix and Prime Video.

Here is the issue I am seeing with my new Vizio. The Roku can be set to Auto or Dolby D+ and I will get these same results. If I start playing a video in Plex with an AC3 5.1 track, it plays fine all the time. But if I play a video in Plex with a TrueHD or DTS track, I get no audio between the Roku and the Vizio. If I then open the Vizio settings and change the audio away from Bitstream (ie: to PCM or Dolby D), audio will start playing. I can then change it BACK to Bitstream and the audio will work properly. At that point I can verify that I’m getting proper 5.1 sound out of the Sonos setup (both in the Sonos app and with my ears).

So this is definitely *not* a format transcoding issue. It seems like it’s some sort of handshake issue between the Roku and the TV… the Roku isn’t communicating to the Vizio that the audio format has changed, but switching the Vizio’s audio setting renegotiates the audio settings and everything comes back to life.

One other question: Is “Dolby D” on the Vizio audio settings to *allow passing* of Dolby D audio? Or is it to *force* a transcode to Dolby D audio? The manual says that you must use Bitstream to pass >2 channels, but any mode other than “PCM” seems to allow that. 
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4 Replies
radiocolin
Level 7

Re: Roku + Vizio audio format issues

When I turn off display refresh rate switching under advanced settings, this problem goes away entirely.
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atc98092
Level 16

Re: Roku + Vizio audio format issues

"radiocolin" wrote:
When I turn off display refresh rate switching under advanced settings, this problem goes away entirely.

I have to disable this setting on my 4640 Ultra when playing MPEG-2 (H.262) video, or else I have noticeable video stuttering. But I have no issue with audio. However, you are attempting to play TrueHD tracks. No Roku supports TrueHD audio. Plex should be transcoding the audio into normal DD, but it sounds like that isn't happening. If you are forcing direct play, that might be the issue. I don't normally use Plex when streaming from my local network, but I do have my Plex server settings to play direct whenever possible. You might look over your Plex settings. 
Dan
Roku Stick (3600), Ultra (4640), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Nvidia Shield, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.
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radiocolin
Level 7

Re: Roku + Vizio audio format issues

The audio is being transcoded by Plex to (E)AC3. I can verify this in my Tautulli dashboard.
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atc98092
Level 16

Re: Roku + Vizio audio format issues

Looking back at your original post makes me think that Vizio changed something your old and new sets. I agree it's some sort of communications issue between the TV and the Roku, but I don't believe it's the fault of the Roku since the change happened after changing the TV. 
Dan
Roku Stick (3600), Ultra (4640), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Nvidia Shield, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.
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