Why Can’t My Receiver Pass Dolby Vision From an Apple TV?

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Q My Denon AVR-S930H receiver supports pass-through of Dolby Vision high dynamic range. However, when I connect my Apple 4K TV to it, the Dolby Vision setting on the Apple box becomes unavailable and the signal changes to the HDR10 high dynamic range format.

I know the Denon passes Dolby Vision because when I connect my Oppo Ultra HD Blu-ray player to it, movies are displayed in the Dolby Vision format on my LG TV. I also know the Apple box isn’t the problem because Dolby Vision works when I connect it directly to the TV. Is there a setting in either the Denon receiver or Apple TV that I’m overlooking? —David A. Pilsner

A Your Denon AVR-S930H does support Dolby Vision pass-through out of the box, so it shouldn’t have problems routing video from the Apple TV 4K when the Enhanced 4K Signal Format option in the receiver’s Video setup menu is selected. That said, when there are three separate devices — an Apple TV box, a receiver, and a TV — in the high dynamic range signal chain, your chance of experiencing problems is increased.

You’ve done most of your troubleshooting work by verifying Dolby Vision pass-through with the Denon using the Oppo player, and Dolby Vision output from the Apple box by connecting it directly to the TV, so your next step should be to verify that each component has been updated to the latest firmware version. That can often be done by checking the system settings in the setup menu.

Updating to the latest firmware is particularly important for the Apple TV 4K. That’s because Apple’s tvOS 11.2 update added the capability for the box to automatically switch output formats to match both the original dynamic range and frame rate of content. (You can set that feature up in the Match Content submenu under the Video and Audio Settings menu.) Prior to tvOS 11.2, the Apple TV 4K would learn your TV’s top capabilities (e.g., Dolby Vision, 4K/60Hz) during initial setup and then force all signals to conform to those formats. Want to watch Seinfeld reruns in high dynamic range? Didn’t think so.

Another thing that Apple recommends to users having HDR problems with the Apple TV 4K is to check your HDMI cables. In theory, most low-cost Premium high-speed HDMI cables should work fine for 4K, HDR10, and Dolby Vision. Still, Apple support recommends using specific cables that have been tested with the Apple TV 4K and other Dolby Vision-compatible devices.

One more option if your problems continue is to connect the Apple TV box directly to the LG TV and route audio back to the Denon using an HDMI ARC (audio return channel) connection. In 2017, LG added support to its TVs for Dolby Digital Plus, a format the Apple TV 4K also supports, over ARC. On earlier LG models, ARC support is limited to regular Dolby Digital.