SDR settings in HDR mode not respected in new release v51.0

[chungyinleo]

Some SDR content stops displaying properly after the newest release 51.0 with the following config

monitorv2 {
  output =
  mode = highrr
  position = auto
  scale = auto
  bitdepth = 10
  vrr = 0
  cm = hdredid
  sdrbrightness = 1
  sdrsaturation = 1
  supports_wide_color = true
  supports_hdr = true
  sdr_min_luminance = 0.005
  sdr_max_luminance = 200
  min_luminance = 0
  max_luminance = 570
  max_avg_luminance = 275
}
render {
  direct_scanout = 0
  cm_fs_passthrough = 1
  cm_auto_hdr = 2
}

I am using an Nvidia card with VK_hdr_layer installed and ENABLE_HDR_WSI always set to 1.

On hyprland v50.1 with this config, playing both SDR and HDR video with mpv works perfectly. No switching between modes were required, so no temporary black screen. SDR video were played with true black and the correct SDR maximum brightness on my OLED display.

With the same config on the new release v51.0, playing SDR video with mpv appears a lot dimmer than it should be. The brightness does not change no matter how I change the sdr_max_luminance, or remove min_luminance = 0 max_luminance = 570. Additionally, no true black anymore for SDR video playback. It appears hyprland is treating mpv as an HDR application instead of an SDR one in the new release, causing the SDR luminance settings to not be respected. If I remember correctly, this behavior is the same as in v49.0. Is this really intended?

I could get around this issue with a slight annoyance by setting cm_fs_passthrough = 1, so it switches to SDR mode when mpv is playing SDR video, but some other non-fullscreen SDR applications (e.g. hyprshell) also look wrong compared to the previous version. Moreover, when mpv is exited, cm is changed to hdr instead of hdredid. This is a weird behavior since returning back to the desktop should respect my cm setting in monitorv2, instead of cm_auto_hdr.

[vaxerski]

@UjinT34 any ideas?

[chungyinleo]

50.1.hyprland.log
50.1.mpv.log
50.1.vkhdrlayer.log
51.0.hyprland.log
51.0.mpv.log
51.0.vkhdrlayer.log

Here are logs.

mpv version 0.40.0
VK_hdr_layer 0-unstable-2025-07-31 from nixos-unstable

I removed my mpv config folder temporarily to reduce the factors. The only options passed are -v --fullscreen

I hope the mpv logs help, but as I said, the issue is not limited to mpv only.

Additionally, playing SDR video with ENABLE_HDR_WSI=0 does work properly even without changing the monitor mode. So I understand it is only very minor issue that I can get around by manually setting the variable to 1 when I play HDR content, and the "real" solution is to wait for Nvidia to properly support HDR. But it was so nice that everything worked wonderfully even with the variable always set to 1 in the last version.

[UjinT34]

Can't reproduce. "a lot dimmer" might not mean incorrect. cm_fs_passthrough = 1 will be incorrect for some SDR cases. sdr_min_luminance = 0.005 with min_luminance = 0 means that both SDR and HDR content black by default are slightly brighter than the monitor black and should be tonemapped (it's unlikely to produce any significant difference with such low values though). cm_auto_hdr shouldn't do anything with cm = hdr*.
Please provide a HL log with HYPRLAND_TRACE=1 and CM proto messages.

[chungyinleo]

hyprland.log
Sorry for the large file. The video I played is a.mp4

How can I obtain the CM proto messages?

[UjinT34]

Try experimental:xx_color_management_v4 = 0. VK_hdr_layer selects the frog cm proto if it's available and this proto wasn't tested with sdr content. In general old frog and xx protos shouldn't be needed anymore.

[chungyinleo]

That works! Thanks a lot!