[PR] avformat/demux: restore container color fields individually (PR #24002)

PR #24002 opened by adorn
URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24002
Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24002.patch

Fixes issue #23717

The upstream change 9b709532d5 ("avformat/demux: don't overwrite
container level color information if set") restores color_primaries,
color_trc and color_space from the container as an all-or-nothing
group: as soon as one of the three is signaled at container level,
all three are taken from the container.

MXF files written by some devices only carry the TransferCharacteristic
UL (MXF local tag 0x3210) but no ColorPrimaries (0x3219) or
CodingEquations (0x321a). For an H.264 essence whose VUI correctly
signals bt709 for all three, the grouped logic overwrites
color_primaries and color_space with the container's UNSPECIFIED
values, so ffprobe reports:

    color_space=unknown / color_primaries=unknown / color_transfer=bt709

instead of the bitstream's bt709/bt709/bt709.

Restore each of the three fields only when it is actually set at the
container level. This keeps container priority where a value is
signaled and falls back to the bitstream (decoder/parser) value
otherwise.

# Summary of changes

Briefly describe what this PR does and why.

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>From 7018f4df1ce31ec4dd78650c7a0d9d1afeeba920 Mon Sep 17 00:00:00 2001
From: adorn <[email protected]>
Date: Mon, 29 Jun 2026 14:50:10 +0200
Subject: [PATCH] avformat/demux: restore container color fields individually

Fixes issue #23717

The upstream change 9b709532d5 ("avformat/demux: don't overwrite
container level color information if set") restores color_primaries,
color_trc and color_space from the container as an all-or-nothing
group: as soon as one of the three is signaled at container level,
all three are taken from the container.

MXF files written by some devices only carry the TransferCharacteristic
UL (MXF local tag 0x3210) but no ColorPrimaries (0x3219) or
CodingEquations (0x321a). For an H.264 essence whose VUI correctly
signals bt709 for all three, the grouped logic overwrites
color_primaries and color_space with the container's UNSPECIFIED
values, so ffprobe reports:

    color_space=unknown / color_primaries=unknown / color_transfer=bt709

instead of the bitstream's bt709/bt709/bt709.

Restore each of the three fields only when it is actually set at the
container level. This keeps container priority where a value is
signaled and falls back to the bitstream (decoder/parser) value
otherwise.
---
 libavformat/demux.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/libavformat/demux.c b/libavformat/demux.c
index 193fd17739..2375b277e4 100644
--- a/libavformat/demux.c
+++ b/libavformat/demux.c
@@ -2587,13 +2587,12 @@ static int parameters_from_context(AVFormatContext *ic, AVCodecParameters *par,
      */
     if (par_tmp->color_range != AVCOL_RANGE_UNSPECIFIED)
         par->color_range = par_tmp->color_range;
-    if (par_tmp->color_primaries != AVCOL_PRI_UNSPECIFIED ||
-        par_tmp->color_trc != AVCOL_TRC_UNSPECIFIED ||
-        par_tmp->color_space != AVCOL_SPC_UNSPECIFIED) {
+    if (par_tmp->color_primaries != AVCOL_PRI_UNSPECIFIED)
         par->color_primaries = par_tmp->color_primaries;
+    if (par_tmp->color_trc != AVCOL_TRC_UNSPECIFIED)
         par->color_trc = par_tmp->color_trc;
+    if (par_tmp->color_space != AVCOL_SPC_UNSPECIFIED)
         par->color_space = par_tmp->color_space;
-    }
     if (par_tmp->chroma_location != AVCHROMA_LOC_UNSPECIFIED)
         par->chroma_location = par_tmp->chroma_location;
 
-- 
2.52.0

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