AppleTV HLG support

Does AppleTV 4K support HLG in any configuration? When I connect my AppleTV 4K to a Samsung TV with HLG support via HDMI

AVPlayer.availableHDRModes.contains(.hlg) returns false


AVPlayer.availableHDRModes.contains(.hdr10) returns true only mentions HDR10 and Dolby Vision support.

Is there any way to play HLG video on AppleTV 4K similar to how it works on newer iPhones and iPads?


Hey Tom, did you hear back on this?
I would also like to know. Our organisation would like to use HLG for our content.
It seems the new upcoming Apple TV 4K (2021) will support HLG over HDMI.

It will have a HDMI 2.1 connection and HLG over HDMI is supported since HDMI 2.0b.

The old/current Apple TV 4K has a HDMI 2.0a connection.
Wondering what your source for this info is,  tom ?

I haven't found anything yet to say the new Apple TV 4K 2021 box will support HLG.
  • Got a 4K 2021 box today. It does not support HLG.

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Wondering what your source for this info is, tom ?

I haven't found anything yet to say the new Apple TV 4K 2021 box will support HLG.

This was just an assumption.

Today I tested with the new Apple TV 4K 2. Gen and unfortunately on none of my TV Sets AVPlayer.availableHDRModes contains .hlg.

It may be that TV is reporting incorrectly, have you tried sending HLG content?

The spec draft-pantos-hls-rfc8216bis (as of rev-07 - April 30, 2020) mentions HLG as a valid value for the VIDEO-RANGE attribute of the EXT-X-STREAM-INF tag. So far as I am aware, you must specify this in order for your streaming content to be recognized as HLG.

I have now tried playing HLS with SDR and HLG and HLG-only.

The new Apple TV 4K 2. Gen with a HDMI 2.1 compatible cable successfully played the HLG variants for both playlists.

The old Apple TV 4K 1. Gen and the Apple TV 4K 2. Gen with an old HDMI cable played the SDR variant of the mixed playlist and failed to play the HLG-only playlist.

This is the desired behaviour.

The downside of AVPlayer.availableHDRModes reporting the support incorrectly is that we cannot show our users if they will be able to play content in HDR.

I posted an answer yesterday, which may still be pending. In any case, I want to add to it. I acquired a new 2021 4K Apple TV yesterday, and it does not appear to support HLG. My test case is the Digital Concert Hall (app from the Berliner Philharmoniker). When I play one of its HLG-encoded programs, the HLG beacon does not light up on my TV, and the picture quality is roughly equivalent to SDR. The same program displays brilliantly, with proper grading, and bright whites without washing out, on a Panasonic Blu-ray player.

I feel it necessary to clarify what I mean by "does not support," because it could be interpreted to mean that HLG programs don't play at all, or that they show as un-decoded HLG. Apple TV is doing something to provide an acceptable picture from an HLG source, but as I said above, the result looks like SDR. As you may be aware, Apple TV's output is set to either HDR or DolbyVision, and its menus and other original material do indeed light up either the HDR or DolbyVision beacon on the TV to which it is attached, depending on which has been chosen in the Apple TV settings (I am using the high-speed HDMI cable ATV requires for Dolby Vision, so that's where I have it). Now, what happens when ATV encounters an HLG signal? One possibility would be that it would process the signal and put it out as, in my case, Dolby Vision; but if that were the case, my LG TV settings would respond to that and provide me with a set of Dolby Vision modes ("Standard," "Cinema," "Vivid," etc.) Instead, it presents me with its corresponding collection of SDR modes. This implies--almost guarantees--that when confronted with HLG material, ATV switches off the Dolby VIsion or standard HDR signal and substitutes SDR.

My conclusion is that ATV "supports" HLG in the sense that it produces an acceptable SDR signal from it, but most definitely not HDR in any sense.

  • On closer examination I see that Apple TV is not attempting to deal with the Digital Concert Hall's (DCH) HLG transmissions at all--because it doesn't have to. The DCH app for ATV, "knowing" that ATV doesn't support HLG, simply presents its programs in 4K SDR, not HDR (HLG). No wonder the result looked like SDR; that's what it was. Smart-players, TV, and streaming apps are all written specifically for particular hardware. In the case of DCH, I experience several versions of it, including an HD version on my LG TV, a 4K HDR version on my Panasonic player, and a 4K SDR version on my ATV.

    My earlier comments were based on my misreading the banners on the DCH programs, which are 4K, UHD, & Hi-Res Audio. I transposed "UHD" to "HDR" in my head because I knew that DCH transmitted HDR on some devices, and I blithely assumed, without really thinking, that it would provide its most advanced signal to ATV, since ATV is one of the very few platforms in which DCH provides Hi-Res audio.

    I am writing from the U. S., and from the various comments, I can see that the situation may be different in other parts of the world. I haven't been able to find any streaming services on my ATV that use HLG; that doesn't mean they don't exist, but based on my experience with DCH, it looks as if ATV does not support HLG in any way. Forget all that I speculated about how ATV might be handling HLG on the DCH--it doesn't.

  • I'm working on the DCH tvOS app. You are correct, that we provide different qualities on different platforms. For tvOS this currently is only SDR. But we are working on changing that. You can contact me directly if you'd like to discuss: t.hess at berliner-philharmoniker dot de

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I have tested playback of HLG stream on NEW Apple TV 4K.

ffprobe color params of this stream was: bt2020nc/bt2020/arib-std-b67 arib-std-b67 is color transfer function used for HLG.

Playback HUD on AppleTV shows video-range HLG, but display switches to HDR10, and display video-range was HDR10.

I think it's normal, AppleTV converting HLG to HDR10, because HLG over HDMI is not supporting

This is correct - I had it confirmed to me by Apple in a bug report, that HLG is correctly recognised but converted to PQ/HDR10 by the Apple TV.

My brand new Apple TV4K (April 2022) does not support HLG HDR. Pictures viewed on my LG TV are better as this format is supported. The BBC in the UK uses this HDR format. So - come on Apple. A software upgrade, please. Otherwise all OK. But..........................