4k audio

@BIslander​ 

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!

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!

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

Thanks for clarifying, user_x1npns. To help isolate the issue, could you please try the following:

Reboot the Xi6-T TV Box by unplugging it for about 30 seconds and then reconnecting it.

Verify the audio settings on the Xi6-T by navigating to Settings > Device Settings > Audio and confirming that Dolby Digital or Auto Detect is selected rather than Stereo/PCM.

If possible, connect the Xi6-T directly to the TV, bypassing the AVR, and check whether the TV reports Dolby Digital audio on a 4K channel. This can help determine whether the issue is occurring between the box and the receiver.

Try a different HDMI cable and, if available, a different HDMI port on the receiver, as some ports may have different audio/video capabilities.

Test multiple 4K channels and 4K On Demand content to see if the behavior is consistent across all 4K programming or only certain broadcasts.

If the receiver continues to show PCM only on 4K channels while Dolby Digital works properly everywhere else, please let us know. 

Thanks. I have been an Xfinity customer for quite some time and I am familiar with the drill. I tried everything that you have suggested except for connecting the box directly to my “TV”. My TV is a projector and unfortunately, the way it is set up the box has to run through my AVR. I do not believe there is any problem between my box and my AVR because non-4K channels pass Dolby digital between the two without any issue whatsoever. The next time I have a chance, while watching a 4K channel, I am going to change my box from the expert audio setting to the auto audio setting to see if that makes any difference. I will report back when I have completed that task.

The 4K channels have Atmos audio even when just running promo loops and static graphics.  So, you can test anytime. 

OK. When the audio is set to auto the 4K channels become Atmos/PCM and all of the non-4K channels become PCM.

When the audio is set to the expert mode, the 4K channels become PCM and all of the non-4K channels become Dolby digital plus.

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.

@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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Info requested sent.  

Update. This is the most recent response I have gotten. 

“Hi Kevin. Thanks for reaching back out. We received an update from our Advanced Repair team stating that the feed format is determined by the broadcaster. Comcast will pass along the information, but we do not dictate the format. In some cases, this may be a setting on either the TV, cable box, sound system, or streaming device. Would you mind verifying if the audio settings are set to Dolby as opposed to PCM? This may mitigate the issue but won't solve it in all cases.”

I have passed your comment along. Thanks for all your insight.

I do not have an Atmos setup, just 5.1. When Auto sends me what it shows as Atmos/PCM, it is processed by my system as a 2 channel input turned into pseudo surround sound. In my case, I believe Atmos should simply down convert to Dolby Digital. Strangely, Auto also turns all standard channels into 2 channel PCM. 

As I had said before, the expert setting transmit all 4K channels as PCM. But it does leave all the other standard channels to transmit as Dolby Digital+.

So you are correct, there is no setting on my box that will get the Audio correct for every channel.