4k audio

Why is the audio on the 4K channels coming through as two channel PCM when the audio on the non-4K channel for the same program is showing as Dolby digital?

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BIslander

Problem Solver

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658 Messages

2 days ago

What box is your Xfinity source? What device is handling your audio?

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U

I have X1 Boxes (Xi6-T). I have a Yamaha RX – A780 AVR. The only problem I have receiving Dolby digital from the box to the AVR is specifically on Xfinity 4K channels. They are only sending a PCM signal to the AVR. On all other channels, the box sends Dolby digital to the AVR just fine.

Thanks!

(edited)

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2 days ago

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BIslander

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658 Messages

2 days ago

I believe the Xi6 started using Dolby MAT on 4K around the time of the Workd Cup with one of its audio output settings, either Auto or Expert, can't remember which. Try switching to the one you aren't using now to see if that makes a difference. My 4K boxes are XG1v4s and they don't use MAT on either setting.

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user_x1npns

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9 Messages

I think I tried switching from expert, the setting I have it on, to auto. but I’ll give that a try again the next time there’s something available on the Xfinity 4K channel. Thanks for the suggestion!

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2 days ago

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BIslander

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658 Messages

2 days ago

In checking back, posts at AVS indicated that the Xi6 starting using MAT on the Auto setting while Expert continued to output DD+.

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user_x1npns

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9 Messages

So, probably not the problem. I’ll try switching anyway. Can’t hurt.

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2 days ago

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XfinitySean

Official Employee

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964 Messages

7 hours ago

Hi there user_x1npns, thanks for taking the time to post here on the community forums! To potentially narrow down the cause of the issue, are you noticing this on any specific 4K channel, or does it seem to be occurring on every 4K channel?

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user_x1npns

Visitor

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9 Messages

5 hours ago

This past weekend, I watched two of the 4K channels. One was a football game. The other was the Southern 500 NASCAR race. So, I’m not sure about every 4K channel, but it has happened on every 4K channel I have watched.

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BIslander

Problem Solver

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658 Messages

4 hours ago

@user_x1npns That's consistent with the world cup change where Auto on the 4K channels produced a Dolby MAT output. Don't know about Yamaha, but it's easy to identify a MAT input on Denons.

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user_x1npns

Visitor

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9 Messages

On my Yamaha, it appears the Dolby MAT is identified as Atmos/PCM.

So the Auto setting is only putting out 2 channel PCM type audio, with or without Atmos attached, which results in only psuedo surround decoding, not actual discreet Dolby Digital?

It still doesn’t explain why the expert setting only outputs PCM on the 4K channels, when it outputs discreet Dolby Digital Plus on all other channels.

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3 hours ago

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XfinityAbby

Official Employee

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1.2K Messages

@user_x1npns I would like to take a further look at the account to see if we can troubleshoot what may be happening.

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2 hours ago

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user_x1npns

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9 Messages

Info requested sent.

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2 hours ago

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BIslander

Problem Solver

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658 Messages

2 hours ago

If memory serves, Xfinity started using 4K AC4 audio on the Xi6 box during the world cup. AC4 is output as MAT and the Xi6 does not transcode it to DD+ on either output setting. It's my recollection that during the world cup people reported getting Atmos or 2.0 PCM for non Atmos content. Seems like that's still happening.

Since support has now taken this out of the public forum, please let us know how things proceed. I'd be amazed if this ends up being unique to something in your setup.

(edited)

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user_x1npns

4k audio

BIslander

user_x1npns

BIslander

user_x1npns

BIslander

user_x1npns

XfinitySean

user_x1npns

BIslander

user_x1npns

XfinityAbby

user_x1npns

BIslander

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