Apple TV Dolby Vision Weirdness

You may have reached the limits of the video settings, where 60 (or 50) Hz + HDR, in combination with other video parameters, is more than at least one of the devices can handle.

One possible cause could be the chroma setting. 4K + Chroma 4:4:4 + 60 Hz + HDR would require more bandwidth than HDMI 2.0 can provide. Instead I suggest using chroma 4:2:0 (no quality loss), as all streaming video is encoded as 4:2:0 anyway, which reduces bandwidth by half (!), leaving enough room for 4K + 60 Hz + HDR.

Streaming content from the iTunes Store may have a lower frame rate (often 24 fps (or Hz)), causing the HDMI signal to dip below the limits for HDMI 2.0 when Match frame rate is active.

There is something to be said for using a default SDR video setting, and only switch to HDR for HDR content (Match dynamic range). Artificially upscaled SDR to HDR looks somewhat unnatural to me, but you do what looks good on your TV.

Exactly. I have my Apple TV 4K 2021 set to SDR with both Match Dynamic Range and Match Frame Rate enabled. My Denon AVR is set to passthrough. When I play Dolby Vision/Dolby Atmos content the Apple TV negotiates a connection with my Sony TV and it switches to whatever the signal coming in is.

Interesting sideline is that virtually 100% of movie content is 4K/24 which is the industry standard for movies. European content often displays 4K/50 and other content shows 4K/60. It takes a few seconds when switching from one format to another. I prefer this over setting a single frame rate and dynamic range that manipulates the incoming signal

You need to make sure that your LG supports Dolby Vision and that it is enabled on the TV. In my personal case I could not get Dolby Vision to enable on the Apple TV 4K even though the specs on my Sony XR-X6590J TV said it did. After reading another user post about their Sony TV I finally found the option buried deep in a submenu in the HDMI Video signal section. Once I enabled Dolby Vision on the Sony the Apple TV 4K popped right up into Dolby Vision. Apparently some TVs don’t have Dolby Vision enabled by default. At least that’s the case I found with my 2021 Sony TV.

So you might want to dig around a little in your LG’s menus or owners manual to make sure. Just a thought. Luckily my Denon AVR reports both the incoming signal from the Apple TV and the outgoing signal to the Sony TV in detail, including frame rate, color depth bits, dynamic range (HDR, Dolby Vision, and Chroma.

It’s been quite a learning experience for me finding out nothing is cut and dried, or simple when it comes to this stuff. Every streaming box and every TV does things a little different.

I’m glad for you. Why all these modern devices don’t use some standardized method to set things up is beyond me. We see all manner of posts from confused users who can’t get their equipment to work like advertised. The interactions between a streaming box (Apple TV, Roku, Firestick, etc), an AVR (Yamaha, Denon, Onkyo, etc.), and a TV (LG, Sony, Samsung, TCL, the list goes on) is bewildering. Every manufacturer seems to do things their own way and the end user gets to sort it all out, often throwing up their hands in disgust and anger. Those who stick with it, like yourself, get a quick education in the myriad of menus and settings that eventually make it all work.

We’re lucky to have people like @Urguhart1244 and you who don’t give up. Thank you for the troubleshooting link you provided. It will certainly help someone else in the future.

Thank you both for your kind words.

Not sure what I said elsewhere on June 2nd (2018 perhaps?) But I’m glad you found it useful.