feat(ffmpeg): Read CICP metadata, and add test

Add test using Matroska + VP9, to try to make the chance of an ffmpeg build
supporting them as high as possible. They are royalty free, built into ffmpeg
and relatively old.

Also recognize mkv (Matroska) extension.

Author: brechtvl

src/cmake/testing.cmake

@@ -250,6 +250,9 @@ macro (oiio_add_all_tests)
                     ENABLEVAR ENABLE_FITS
                     IMAGEDIR fits-images
                     URL http://www.cv.nrao.edu/fits/data/tests/)
+    oiio_add_tests (ffmpeg
+                    ENABLEVAR ENABLE_FFMPEG
+                    FOUNDVAR FFmpeg_FOUND)
     oiio_add_tests (gif
                     FOUNDVAR GIF_FOUND ENABLEVAR ENABLE_GIF
                     IMAGEDIR oiio-images/gif URL "Recent checkout of OpenImageIO-images")

src/ffmpeg.imageio/ffmpeginput.cpp

@@ -180,9 +180,9 @@ ffmpeg_input_imageio_create()
 // QuickTime / MOV
 // raw MPEG-4 video
 // MPEG-1 Systems / MPEG program stream
-OIIO_EXPORT const char* ffmpeg_input_extensions[] = {
-    "avi", "mov", "qt", "mp4", "m4a", "3gp", "3g2", "mj2", "m4v", "mpg", nullptr
-};
+OIIO_EXPORT const char* ffmpeg_input_extensions[]
+    = { "avi", "mov", "qt",  "mp4", "m4a", "3gp",
+        "3g2", "mj2", "m4v", "mpg", "mkv", nullptr };
 
 
 OIIO_PLUGIN_EXPORTS_END
@@ -531,6 +531,12 @@ FFmpegInput::open(const std::string& name, ImageSpec& spec)
     m_spec.attribute("oiio:BitsPerSample",
                      m_codec_context->bits_per_raw_sample);
     m_spec.attribute("ffmpeg:codec_name", m_codec_context->codec->long_name);
+    /* The ffmpeg enums are documented to match CICP values, except the color range. */
+    const int cicp[4]
+        = { m_codec_context->color_primaries, m_codec_context->color_trc,
+            m_codec_context->colorspace,
+            m_codec_context->color_range == AVCOL_RANGE_MPEG ? 0 : 1 };
+    m_spec.attribute("CICP", TypeDesc(TypeDesc::INT, 4), cicp);
     m_nsubimages = m_frames;
     spec         = m_spec;
     m_filename   = name;

testsuite/ffmpeg/ref/out.txt

@@ -0,0 +1,87 @@
+Reading ref/vp9_display_p3.mkv
+ref/vp9_display_p3.mkv :  192 x  108, 3 channel, uint8 FFmpeg movie
+    7 subimages: 192x108 [u8,u8,u8]
+ subimage  0:  192 x  108, 3 channel, uint8 FFmpeg movie
+    SHA-1: C882152FF48CB068931C2710175659A9D0493C08
+    channel list: R, G, B
+    CICP: 12, 1, 1, 1
+    DATE: "2025/09/13 21:58:33"
+    ENCODER: "Lavf61.7.100"
+    FramesPerSecond: 24/1 (24)
+    SCENE: "Scene"
+    ffmpeg:codec_name: "Google VP9"
+    oiio:BitsPerSample: 0
+    oiio:Movie: 1
+    oiio:subimages: 7
+ subimage  1:  192 x  108, 3 channel, uint8 FFmpeg movie
+    SHA-1: 1E2EB62F7BDD2DAC5C6FBDE582EE19978DC7C290
+    channel list: R, G, B
+    CICP: 12, 1, 1, 1
+    DATE: "2025/09/13 21:58:33"
+    ENCODER: "Lavf61.7.100"
+    FramesPerSecond: 24/1 (24)
+    SCENE: "Scene"
+    ffmpeg:codec_name: "Google VP9"
+    oiio:BitsPerSample: 0
+    oiio:Movie: 1
+    oiio:subimages: 7
+ subimage  2:  192 x  108, 3 channel, uint8 FFmpeg movie
+    SHA-1: 1E2EB62F7BDD2DAC5C6FBDE582EE19978DC7C290
+    channel list: R, G, B
+    CICP: 12, 1, 1, 1
+    DATE: "2025/09/13 21:58:33"
+    ENCODER: "Lavf61.7.100"
+    FramesPerSecond: 24/1 (24)
+    SCENE: "Scene"
+    ffmpeg:codec_name: "Google VP9"
+    oiio:BitsPerSample: 0
+    oiio:Movie: 1
+    oiio:subimages: 7
+ subimage  3:  192 x  108, 3 channel, uint8 FFmpeg movie
+    SHA-1: 1E2EB62F7BDD2DAC5C6FBDE582EE19978DC7C290
+    channel list: R, G, B
+    CICP: 12, 1, 1, 1
+    DATE: "2025/09/13 21:58:33"
+    ENCODER: "Lavf61.7.100"
+    FramesPerSecond: 24/1 (24)
+    SCENE: "Scene"
+    ffmpeg:codec_name: "Google VP9"
+    oiio:BitsPerSample: 0
+    oiio:Movie: 1
+    oiio:subimages: 7
+ subimage  4:  192 x  108, 3 channel, uint8 FFmpeg movie
+    SHA-1: 35565DB895AB1CA413192B7F25A1890718CFC0F5
+    channel list: R, G, B
+    CICP: 12, 1, 1, 1
+    DATE: "2025/09/13 21:58:33"
+    ENCODER: "Lavf61.7.100"
+    FramesPerSecond: 24/1 (24)
+    SCENE: "Scene"
+    ffmpeg:codec_name: "Google VP9"
+    oiio:BitsPerSample: 0
+    oiio:Movie: 1
+    oiio:subimages: 7
+ subimage  5:  192 x  108, 3 channel, uint8 FFmpeg movie
+    SHA-1: 338C9A82B74CE3B291DAD6564AE7C060AE6D9267
+    channel list: R, G, B
+    CICP: 12, 1, 1, 1
+    DATE: "2025/09/13 21:58:33"
+    ENCODER: "Lavf61.7.100"
+    FramesPerSecond: 24/1 (24)
+    SCENE: "Scene"
+    ffmpeg:codec_name: "Google VP9"
+    oiio:BitsPerSample: 0
+    oiio:Movie: 1
+    oiio:subimages: 7
+ subimage  6:  192 x  108, 3 channel, uint8 FFmpeg movie
+    SHA-1: 90BC91EAA745A9C897EEDEC0D34BAAF1D40B1C7C
+    channel list: R, G, B
+    CICP: 12, 1, 1, 1
+    DATE: "2025/09/13 21:58:33"
+    ENCODER: "Lavf61.7.100"
+    FramesPerSecond: 24/1 (24)
+    SCENE: "Scene"
+    ffmpeg:codec_name: "Google VP9"
+    oiio:BitsPerSample: 0
+    oiio:Movie: 1
+    oiio:subimages: 7

testsuite/ffmpeg/ref/vp9_display_p3.mkv

@@ -0,0 +1,10 @@
+#!/usr/bin/env python
+
+# Copyright Contributors to the OpenImageIO project.
+# SPDX-License-Identifier: Apache-2.0
+# https://github.com/AcademySoftwareFoundation/OpenImageIO
+
+imagedir = "ref/"
+files = [ "vp9_display_p3.mkv" ]
+for f in files:
+    command = command + info_command (os.path.join(imagedir, f))