1870631 - [regression] YouTube forces HDR on some videos (on a non-HDR screen)

Status: UNCONFIRMED

(Core :: Audio/Video: Playback, defect, P3)

Description

[gregard]

Firefox 120.0.1 (64-bit) on Mac displays HDR YouTube-videos, even when the display on client is SDR.

Easily reproducible:

1. Play video: https://www.youtube.com/watch?v=aLQGkXD3HG8
2. Right click on video og show stats for nerds.
3. Observe that Settings Quality says HDR, even when display is SDR only.

It shows Color: smpte2084 (PQ / bt2020 ) which is HDR. Should be Rec 709 on SDR displays.

PS: Don't test this on a new Mac laptop, as it most likely has a HDR display.

Old bug report from 4 years ago, seems to be back on Mac:
As seen on reddit: https://www.reddit.com/r/firefox/comments/d33st1/why_does_firefox_force_you_to_watch_youtube_in/

STR:

1. Navigate to https://www.youtube.com/watch?v=b5oTiLmEdgU
2. Play video

What happens:

The video plays back in HDR, and the resolution switcher in YouTube does not allow the user to switch back to SDR video. This results in washed out video.

Expected result:

I don't have an HDR display; I don't expect YouTube's player to serve me HDR content.

17:20.35 INFO: Last good revision: a7b675fcb8d31cbbdfcf9179303d49ec294647e0
17:20.35 INFO: First bad revision: 43b78a85f3266f65c0ed4045e28c16dec90b480c
17:20.35 INFO: Pushlog:
https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=a7b675fcb8d31cbbdfcf9179303d49ec294647e0&tochange=43b78a85f3266f65c0ed4045e28c16dec90b480c

Comment 1

[Jim Mathies [:jimm]]

Falsely reporting hdr support issue maybe? Brad, any thoughts?

Comment 2

[Brad Werth [:bradwerth]]

I'll figure this out.

Comment 3

[Brad Werth [:bradwerth]]

I'm having trouble reproducing this. In theory, YouTube's HDR detection is based on Firefox matching the media query video-dynamic-range: high which we do for any Mac that reports itself to be HDR capable. We match this incorrectly if the video is being displayed on an external SDR monitor (which is Bug 1764201). Is that the case here? Are you viewing the video on an external SDR monitor?