HDR

You get a 10-bit HDR10 (BT.2020 PQ) stream when every link below holds; otherwise the session streams 8-bit SDR. The host settles this before the first frame, so reconnect after changing anything on this page.

The chainCopy Anchor Link

1. The host allows it. Host → Video → 10-bit and HDR (PUNKTFUNK_10BIT), on by default.
2. The source delivers 10-bit PQ. This is the link that fails most — see Per host.
3. The codec has a 10-bit path: HEVC, AV1 or PyroWave. H.264 has none, so pinning H.264 on the client pins SDR.
4. The host GPU encodes 10-bit for that codec. The host test-opens an encoder once per GPU and codec and believes the answer.
5. The client asks for HDR with its HDR setting — see Per client.

Per hostCopy Anchor Link

WindowsCopy Anchor Link

Nothing to set. The host turns HDR on for the session's virtual display when the session is HDR, and forces it off for an SDR session; Windows' own Use HDR switch doesn't matter.

• The encoder must be NVENC, AMF, QSV or PyroWave. A Windows on Arm host (Media Foundation) or a software-encoding host streams SDR.
• If Windows refuses to turn HDR on, the host logs an error and streams SDR although the client was told HDR. This is the one case where the client's HDR label is wrong.
• Switching HDR off on the virtual display during a session (Win+Alt+B on the host) turns the stream SDR until HDR is back on.
• Vulkan games need the installer's HDR Vulkan layer (on by default); see the troubleshooting entry.

Linux + gamescopeCopy Anchor Link

The Linux route to HDR on KDE and GNOME, and in Game Mode everywhere.

1. Have punktfunk-gamescope; stock gamescope captures 8-bit. The host packages install it; HDR on gamescope covers every distro.
2. Restart the host. It reads what the gamescope build can do once, at startup.
3. Let the host start the gamescope session, which is the default. A session it attaches to instead streams SDR: turn off Attach mode under Host → Game Mode, or delete the PUNKTFUNK_GAMESCOPE_ATTACH line from host.env if the row says that file set it.
4. For Steam's own HDR setting to be available, the build must be +pfhdr14 or newer. Check with punktfunk-gamescope --version.

SDR content in an HDR session (the desktop, the Steam UI, SDR games) starts at Host → Game Mode → SDR brightness (advanced, PUNKTFUNK_GAMESCOPE_SDR_NITS): 203 nits, the level the clients expect. Steam's SDR brightness setting moves it during the session. Builds older than +pfhdr16 ignore both and show SDR content oversaturated.

Game Mode HDR (PUNKTFUNK_GAMESCOPE_HDR) on the same page, turned off, keeps gamescope sessions SDR.

Linux + GNOMECopy Anchor Link

GNOME HDR reaches Moonlight only, by mirroring a real monitor (GNOME 50+). A Punktfunk app connecting to a GNOME host gets SDR.

1. Add PUNKTFUNK_VIDEO_SOURCE=portal to host.env and restart the host.
2. Put the monitor in HDR mode in GNOME Settings → Displays.
3. Connect with HDR on in Moonlight.

With PUNKTFUNK_CAPTURE_MONITOR=<connector> set, only that monitor's HDR mode counts. If no monitor is in HDR mode, the session streams SDR and says so in the host log.

Linux + HyprlandCopy Anchor Link

A virtual display is lit in 10-bit HDR when the client asks for HDR: the host adds bitdepth 10, cm hdr, supports_hdr and supports_wide_color to the streamed head's monitor rule. SDR content inside it starts at SDR brightness (the Game Mode setting, 203 nits). The client panel's volume, when the app sends it, becomes the head's mastering target. An older Hyprland that refuses those keys streams SDR until the host restarts.

HDR needs Hyprland's colour management, which is on by default. With render:cm_enabled = false the session streams SDR.

Streaming a physical monitor on Hyprland is HDR when that monitor is in HDR mode. Nothing to set on the host.

Other Linux desktopsCopy Anchor Link

SDR. KDE and GNOME's virtual displays capture 8-bit, and so does streaming a physical monitor on KDE to a Punktfunk app. No setting changes this.

Per clientCopy Anchor Link

HDR is on by default in every client and can differ per preset. The toggle sits with the other video settings.

10-bit SDRCopy Anchor Link

The client's 10-bit SDR setting asks for a 10-bit stream without HDR.

A Windows 11 24H2 (or later) host composes the virtual display in wide colour for that session, and Windows shows it as a 10-bit display. The stream then carries the desktop's own bits past 8, wherever a game or app renders them. Composing in wide colour costs some GPU time.

Other desktops hand the host only 8 bits of SDR, so the host could only widen each frame: smoother gradients after the encoder, one more colour pass on the GPU, no detail the desktop didn't have. There the host streams 8-bit SDR unless Host → Video → Allow 10-bit SDR (PUNKTFUNK_10BIT_SDR_WIDEN, advanced, off by default) is on.

HDR and 4:4:4Copy Anchor Link

Full chroma and HDR together:

AV1 is always 4:2:0.

Check itCopy Anchor Link

On the client, set the stats overlay to Detailed. Its first line names the codec and depth, then HDR for an HDR stream on an HDR display, or HDR→SDR when the Linux or Windows client tone-maps it because the display offers no HDR10.

On a Linux host, one command checks every link:

punktfunk-host hdr-probe

It reports the monitor's HDR mode, whether the gamescope build offers 10-bit capture, the Game Mode HDR setting, the encoder's 10-bit answer for HEVC and AV1, and whether the resolved compositor and the GameStream side can do HDR. The service reads host.env and your shell doesn't, so load it first, or the answers describe your shell:

set -a; . ~/.config/punktfunk/host.env; set +a
punktfunk-host hdr-probe

On Windows, hdr-p010-selftest checks the GPU's HDR colour conversion instead.

TroubleshootingCopy Anchor Link

The stream is SDRCopy Anchor Link

The host logs an encode bit depth line per session. The first false among host_wants_10bit, capture_supports_hdr, client_wants_hdr and gpu_can_10bit names the missing link of the chain: the host setting, the source, the client, or the codec and GPU.

HDR stopped working on a Linux hostCopy Anchor Link

The log says HDR capture negotiation failed. After that the host offers SDR: on gamescope until that display closes, on the GNOME monitor mirror until the host restarts. Fix the cause (usually a gamescope that isn't the Punktfunk build, or a monitor out of HDR mode), then reconnect or restart.

A Vulkan game on Windows says HDR isn't supportedCopy Anchor Link

NVIDIA and AMD Vulkan drivers hide HDR from games on a virtual display. The installer's HDR Vulkan layer option (VK_LAYER_PUNKTFUNK_hdr_inject) shows it to them again; re-run the installer with it ticked. The layer does nothing in an SDR session or on a physical monitor, and skips a built-in list of anti-cheat titles. To turn it off for one game, set DISABLE_PF_VKHDR=1 in its environment, or list executables in PF_VKHDR_EXCLUDE=foo.exe,bar.exe. D3D11 and D3D12 games don't need it.

An HDR stream is green on a Windows client with an AMD GPUCopy Anchor Link

AMD drivers older than AMD Software 25.9.1 draw HDR wrong on the Vulkan decoder; the client warns about it. Update the driver, or set Video decoder to Hardware (Direct3D 11 / DXVA).