Weird Apple TV sound glitch
I posted this today on Twitter...but I suspect it's more suited for this Forum. So here goes:
Totally bizarre Apple TV (4th gen) glitch: It lost sound. Settings > Audio shows HDMI option missing. (The video option also reverts to RGB; the YCbCr option is gone.) It’s like ATV doesn’t see the cable. But if I restart ATV and receiver (to which ATV connects), all works fine again — HDMI option is back. No need to do anything with the cable. But then the problem returns after awhile.
Oddity: If I switch directly from TiVo to ATV, problem typically occurs. But if I turn everything off and turn back on directly to ATV — sound usually works. Stranger still…
If I swap ATV 4 with my ATV 3 connected to another TV — both work fine. Did this for weeks with no sound problem at either location. After I returned ATVs to original locations, sound glitch reappeared a day or so later with ATV 4.
If cause was the HDMI cable, I would assume it would affect both ATV units (I should still try a new cable I suppose). But if it was clearly the ATV 4 itself, I would expect it would have a problem in both locations. Odd. I would add that this ATV 4 has been working for several years with no issues. This all started recently. On baIance, I am assuming a strange ATV 4 defect.
Not having problems like this with any other components.
I agree with @davehamilton that it could be your HDMI cable as the HDCP copy protection could be not getting passed through properly from your Apple TV 4 to the receiver but I am more inclined to believe it is your receiver that is at fault and not the Apple TV 4 as it is what is doing the switching/routing of your video and audio.
If your setup allows for it, you could try plugging in the Apple TV 4 directly in to your TV with your existing HDMI cable and see if the problem still happens. If not then you will know it is your receiver or you could see about swapping out the HDMI cable. Those would be my two next things to do. Depending on your setup, swapping out the HDMI cable may be easier than moving the Apple TV 4.
FYI: Things have got stranger rather than better. The other day, the ATV 4 stopped showing VIDEO (new symptom) as well as having no audio. I tried a new HDMI cable, as suggested here. It had no effect.
So I once again swapped my two ATV's. And once again, they both work fine in their new locations. The ATV 4 now has both video and audio in its swapped location. And the ATV 3 works in the location where the ATV 4 would not. So odd.
The only thing I can think of at this point is some weird interaction specific to the ATV 4 and the receiver to which it connects where the problem occurs. Even here, it's strange that the problem only first cropped up a few weeks ago — in a setup that has been stable for years.
Anyway, I've decided I will leave them swapped for now...and probably get a new ATV at some point.
Thanks for the update. Yes. The signs do point to it being your amp/receiver as the problem and not the ATV. While I am sure picking up a new amp/receiver is more expensive than an ATV 4 but it does look like it will solve the problem.
True. It is guesswork for now but getting to the bottom of it will require doing more troubleshooting to see what is causing the problem. You make a good point that you could try and plug in your ATV 4 in to a different HDMI port on your existing amp/receiver to see if that changes anything. However, I know that in some setups that could be tricky and possibly require reprogramming your amp/receiver and universal remote to get the sound and video to work.
So I can see how just picking up a new ATV 4/5 may be the easier thing to try to troubleshoot this problem with the added benefit that you could retire your ATV 3 that is a number of years old and does not run tvOS so while it still works for now, the support from both Apple and various 3rd parties is just not going to be there long term.