Plex displays wrong colours with Dolby Vision on AppleTV 4k

Plex Players Streaming Devices
125

I’m hoping that means you’ve straightened out expectations, but just so we’re all clear:

  • Plex should support Dolby Vision Profile 5 (dvhe.05) at various levels, generally 5 thru 7 (dvhe.05.05, dvhe.05.06, dvhe.05.07).
  • The reason dvhe.05 content is showing incorrect colors when played back in Plex today is because the profile uses Dolby’s ICpCt/IPT color space instead of BT.2020 used in HDR10. So there’s no fallback to HDR10 that displays correctly.
  • There’s no expectation that Plex support Profile 7 (dvhe.07) until such point it’s possible to support it in software or hardware, as the Apple TV 4K (2017/2021) doesn’t support it.
  • The reason your dvhe.07 files were appearing correctly in your testing is because the Base Layer (BL) is HDR10-compatible, meaning dvhe.07 uses the same BT.2020 color space as HDR10 and contains the same static metadata. So Plex and the Apple TV are falling back to HDR10 playback with those files, ignoring the Full Enhancement Layer (FEL, a second 1080p video stream that adds additional video information to support full 12-bit color, plus the DoVi dynamic metadata (RPU)) or the Minimal Enhancement Layer (MEL, a second stream with no video information that carries just the RPU).
  • There’s no expectation that Plex support Profile 8 (dvhe.08) until such point it’s possible to support it in software or hardware, as the Apple TV 4K (2017/2021) doesn’t appear to support it. While Profile 8.1 is HDR10-compatible because the video stream uses the same PQ transfer function and BT.2020 color space (and the RPU is just ignored when falling back to HDR10), Profile 8.4 uses HLG, so it’s a totally different story. It’s possible Profile 8.4 is or will be supported on the ATV4K at some point with a software update because the iPhone 12 Pro uses 8.4, but it doesn’t appear playback is supported on the ATV4K today.
  • The ATV4K 2021 model does add explicit support for HLG and 2160p60 HDR playback, which are not included in the supported playback modes for the ATV4K 2017 model. So it’s possible there may be a difference in what Plex can support across the different generations of the ATV4K specifically for 4K HDR @ 60fps playback, HLG playback, and therefore DoVi Profile 8.4 support. Even if Profile 8.4 isn’t supported, the A12 Bionic SoC in the ATV4K 2021 model should support HLG playback today, falling back to static metadata for HDR if the Profile 8.4 RPU can’t be processed.

This post at AV Discourse has a good overview on demystifying DoVi profiles & levels.

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