avutil: introduce AVAmbientViewingEnvironment side data

This enables exposing H.274 Ambient Viewing Environment
metadata in the framework.

1 files changed, 72 insertions, 0 deletions

diff --git a/libavutil/ambient_viewing_environment.h b/libavutil/ambient_viewing_environment.h
new file mode 100644
index 0000000000..e5e4ac2173
--- /dev/null
+++ b/libavutil/ambient_viewing_environment.h
@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) 2023 Jan Ekström <jeebjp@gmail.com>
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVUTIL_AMBIENT_VIEWING_ENVIRONMENT_H
+#define AVUTIL_AMBIENT_VIEWING_ENVIRONMENT_H
+
+#include <stddef.h>
+#include "frame.h"
+#include "rational.h"
+
+/**
+ * Ambient viewing environment metadata as defined by H.274. The values are
+ * saved in AVRationals so that they keep their exactness, while allowing for
+ * easy access to a double value with f.ex. av_q2d.
+ *
+ * @note sizeof(AVAmbientViewingEnvironment) is not part of the public ABI, and
+ *       it must be allocated using av_ambient_viewing_environment_alloc.
+ */
+typedef struct AVAmbientViewingEnvironment {
+    /**
+     * Environmental illuminance of the ambient viewing environment in lux.
+     */
+    AVRational ambient_illuminance;
+
+    /**
+     * Normalized x chromaticity coordinate of the environmental ambient light
+     * in the nominal viewing environment according to the CIE 1931 definition
+     * of x and y as specified in ISO/CIE 11664-1.
+     */
+    AVRational ambient_light_x;
+
+    /**
+     * Normalized y chromaticity coordinate of the environmental ambient light
+     * in the nominal viewing environment according to the CIE 1931 definition
+     * of x and y as specified in ISO/CIE 11664-1.
+     */
+    AVRational ambient_light_y;
+} AVAmbientViewingEnvironment;
+
+/**
+ * Allocate an AVAmbientViewingEnvironment structure.
+ *
+ * @return the newly allocated struct or NULL on failure
+ */
+AVAmbientViewingEnvironment *av_ambient_viewing_environment_alloc(size_t *size);
+
+/**
+ * Allocate and add an AVAmbientViewingEnvironment structure to an existing
+ * AVFrame as side data.
+ *
+ * @return the newly allocated struct, or NULL on failure
+ */
+AVAmbientViewingEnvironment *av_ambient_viewing_environment_create_side_data(AVFrame *frame);
+
+#endif /* AVUTIL_AMBIENT_VIEWING_ENVIRONMENT_H */