Merge pull request #2144 from ssandweiss/fix/2142-sdr-colr-export

fix(export): tag SDR exports with a colr box (#2142)

crates/export/src/hdr_tests.rs

@@ -199,3 +199,17 @@ fn the_software_h264_sei_is_the_static_metadata_laid_out_as_messages() {
     want.push(0x80);
     assert_eq!(sei, want);
 }
+
+/// #2142: SDR gets its `colr` box as well (nclc in MOV, nclx in MP4), and no HDR metadata.
+#[test]
+fn sdr_gets_a_colr_box_and_no_hdr_metadata() {
+    let mut e = filmcraft_isobmff::SampleEntry::prores(filmcraft_isobmff::FourCc(*b"apch"), 64, 64);
+    ColorSignal::default().apply_to(&mut e, true);
+    let v = e.video.as_ref().unwrap();
+    assert_eq!(v.color, Some(filmcraft_isobmff::ColorInfo::Nclc { primaries: 1, transfer: 1, matrix: 1 }));
+    assert!(v.mastering_display.is_none() && v.content_light.is_none());
+    let mut e = filmcraft_isobmff::SampleEntry::hevc(Default::default(), 64, 64);
+    ColorSignal::default().apply_to(&mut e, false);
+    let v = e.video.as_ref().unwrap();
+    assert_eq!(v.color, Some(filmcraft_isobmff::ColorInfo::Nclx { primaries: 1, transfer: 1, matrix: 1, full_range: false }));
+}

crates/export/src/lib.rs

@@ -520,11 +520,10 @@ impl ColorSignal {
         if self.matrix == 9 { (0.2627, 0.0593) } else { (0.2126, 0.0722) }
     }
     /// Sample-entry boxes: `colr` (nclx for MP4, nclc for MOV) plus `mdcv`/`clli` for PQ
-    /// (mastering display BT.2020/D65, 1000/0.0001 cd/m²; MaxCLL/MaxFALL 0 = unknown).
+    /// (mastering display BT.2020/D65, 1000/0.0001 cd/m²; MaxCLL/MaxFALL 0 = unknown). SDR gets
+    /// its `colr` too: Apple's media stack (QuickTime Player, Final Cut Pro) reads the colour of
+    /// ProRes, DNxHR and APV only from this box, not from their frame headers (#2142).
     pub fn apply_to(&self, e: &mut SampleEntry, mov: bool) {
-        if !self.is_hdr() {
-            return;
-        }
         if let Some(v) = e.video.as_mut() {
             let (p, t, m) = (self.primaries as u16, self.transfer as u16, self.matrix as u16);
             v.color = Some(if mov {

crates/export/src/tests.rs

@@ -126,6 +126,31 @@ fn prores_export_roundtrip() {
     assert!(f[0] > 240 && f[1] < 15 && f[2] < 15, "{:?}", &f[..4]);
 }
 
+/// #2142: SDR ProRes, DNxHR and APV (MOV) and H.264 (MP4) exports carry a `colr` box with the
+/// export's BT.709 colour: Apple's media stack reads the colour of the MOV codecs only from there.
+#[test]
+fn sdr_exports_carry_a_colr_box() {
+    use filmcraft_isobmff::ColorInfo;
+    let (p, seq, m) = project();
+    let nclc = ColorInfo::Nclc { primaries: 1, transfer: 1, matrix: 1 };
+    let nclx = ColorInfo::Nclx { primaries: 1, transfer: 1, matrix: 1, full_range: false };
+    for (format, name, want) in [
+        (Format::ProRes, "colr-prores.mov", nclc.clone()),
+        (Format::DnxHr, "colr-dnxhr.mov", nclc.clone()),
+        (Format::Apv, "colr-apv.mov", nclc.clone()),
+        (Format::H264, "colr-h264.mp4", nclx),
+    ] {
+        let path = tmp(name);
+        export(&p, seq, &ExportSettings { format, path: path.clone(), include_audio: false, ..Default::default() }, &m, &Progress::default()).unwrap();
+        let bytes = std::fs::read(&path).unwrap();
+        let file = filmcraft_isobmff::open(bytes).unwrap();
+        let t = file.track_of_kind(filmcraft_isobmff::TrackKind::Video).unwrap();
+        let v = file.tracks[t].entries[0].video.as_ref().unwrap();
+        assert_eq!(v.color.as_ref(), Some(&want), "{name}");
+        assert!(v.mastering_display.is_none() && v.content_light.is_none(), "{name}: no HDR metadata on SDR");
+    }
+}
+
 /// ProRes 4444 / 4444 XQ export (#342): 4:4:4 frames under the `ap4h` / `ap4x` codes, and with
 /// Include Alpha Channel the picture's alpha survives instead of being flattened over black.
 #[test]