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fix(video): honor the signaled CSC matrix end-to-end + tvOS HDR presentation

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Clients derive Y'CbCr->RGB from the stream's SIGNALED matrix x range x depth
via shared csc rows (Rust csc_rows + Swift CscRows) instead of hardcoded
709/2020 - a BT.601-signaled stream (a Linux host's RGB-input NVENC) no longer
renders with a constant hue error. Host-side signaling made honest across
NVENC/VAAPI/openh264/GameStream and the session plan's chroma/bit-depth.
Decoded color-bar fixtures (601/709 x limited/full) pin the math in tests on
both cores.

Same presenter, tvOS HDR: tvOS has no Metal EDR API and a bare PQ colorspace
tag composites UNTONE-MAPPED (the "overblown" Apple TV report), so HDR now
splits on the display's live EDR headroom - PQ passthrough when the
per-session AVDisplayManager mode switch landed (a real HDR10 output
tone-maps itself), else an in-shader PQ->SDR tone-map (203-nit reference
white, extended-Reinhard 1000-nit knee, 2020->709) into the proven SDR layer
config. The 10-bit stream keeps its full decode depth either way.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
This commit is contained in:
Enrico Bühler
2026-07-10 16:58:11 +02:00
parent db49904c6d
commit 1fcf9e11ec
26 changed files with 2268 additions and 409 deletions
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crates/punktfunk-host/src/encode/linux/mod.rs
+22 -8
View File
@@ -326,11 +326,19 @@ impl NvencEncoder {
};
}
// NV12 / 4:4:4 paths: we do the RGB→YUV conversion ourselves as BT.709 *limited* range
// (swscale), so signal that in the bitstream VUI (colorspace/range/primaries/transfer) —
// otherwise the client decoder assumes a default and the picture comes out washed-out /
// wrong-contrast. The RGB-input 4:2:0 path leaves these unset (NVENC's internal CSC writes
// its own VUI). Matches the Windows NV12 path's BT.709 limited-range signalling.
// NV12 / 4:4:4 paths: we do the RGB→YUV conversion ourselves as BT.709 (swscale), so
// signal that in the bitstream VUI (colorspace/range/primaries/transfer) — otherwise the
// client decoder assumes a default and the picture comes out washed-out / wrong-contrast.
// The RGB-input 4:2:0 path leaves these unset (NVENC's internal CSC writes its own VUI).
// Matches the Windows NV12 path's BT.709 limited-range signalling.
//
// PUNKTFUNK_444_FULLRANGE=1 (experimental, 4:4:4-only): convert AND signal FULL range —
// recovers the ~12% of code space limited-range quantization gives up, for the exact
// text/UI chroma 4:4:4 exists for. Every punktfunk client honors the signaled range
// (csc_rows / the Apple rows port); ship as default only if the on-glass A/B shows a
// visible win. Linux-only: the Windows path's NVENC-internal CSC range is unmeasured.
let full_range_444 = want_444
&& std::env::var("PUNKTFUNK_444_FULLRANGE").is_ok_and(|v| v.trim() == "1");
if matches!(format, PixelFormat::Nv12) || want_444 {
// SAFETY: same `video` builder — `raw = video.as_mut_ptr()` is the non-null, properly-
// aligned, sole-owned, not-yet-opened `AVCodecContext`. We set its four VUI colour enum
@@ -339,7 +347,11 @@ impl NvencEncoder {
unsafe {
let raw = video.as_mut_ptr();
(*raw).colorspace = ffi::AVColorSpace::AVCOL_SPC_BT709;
(*raw).color_range = ffi::AVColorRange::AVCOL_RANGE_MPEG; // limited/studio
(*raw).color_range = if full_range_444 {
ffi::AVColorRange::AVCOL_RANGE_JPEG // full
} else {
ffi::AVColorRange::AVCOL_RANGE_MPEG // limited/studio
};
(*raw).color_primaries = ffi::AVColorPrimaries::AVCOL_PRI_BT709;
(*raw).color_trc = ffi::AVColorTransferCharacteristic::AVCOL_TRC_BT709;
}
@@ -401,10 +413,12 @@ impl NvencEncoder {
// SAFETY: `sws` is the non-null context from the call above (null-checked). The ITU-709
// coefficient table from `sws_getCoefficients` is a process-lifetime libswscale static,
// reused for src+dst matrices; `sws_setColorspaceDetails` only reads it and writes scalar
// CSC settings into `sws` (limited-range dst: dstRange = 0). No Rust memory is passed.
// CSC settings into `sws` (dstRange matches the VUI: 0 = limited, 1 = the
// PUNKTFUNK_444_FULLRANGE experiment). No Rust memory is passed.
unsafe {
let cs709 = ffi::sws_getCoefficients(SWS_CS_ITU709);
ffi::sws_setColorspaceDetails(sws, cs709, 1, cs709, 0, 0, 1 << 16, 1 << 16);
let dst_range = i32::from(full_range_444);
ffi::sws_setColorspaceDetails(sws, cs709, 1, cs709, dst_range, 0, 1 << 16, 1 << 16);
}
Some(sws)
} else {