[FFmpeg-devel] [PATCH 1/3] lavu: add support for Content Light Level side metadata

[Steve Lhomme]

As found in HEVC.

I put the code in mastering_display_metadata as they usually go together in
Blu-Ray UHD sources.

--
update the previous patch:
- rename CEA 861.3 to CTA-861.3
- use MaxCLL and MaxFALL names that are more commonly found
- use unsigned integer rather than rational numbers as (supposedly) in the specs
- provide the structure size on output of av_content_light_metadata_alloc()
update the previous patch:
- rebased and updated version bump
update the previous patch:
- rebased and updated version bump
- fix contains typo
---
 libavutil/frame.c                      |  1 +
 libavutil/frame.h                      |  6 ++++++
 libavutil/mastering_display_metadata.c | 23 ++++++++++++++++++++
 libavutil/mastering_display_metadata.h | 39 ++++++++++++++++++++++++++++++++++
 libavutil/version.h                    |  2 +-
 5 files changed, 70 insertions(+), 1 deletion(-)

diff --git a/libavutil/frame.c b/libavutil/frame.c
index 8811dcdcfe..dd12c5549c 100644
--- a/libavutil/frame.c
+++ b/libavutil/frame.c
@@ -772,6 +772,7 @@ const char *av_frame_side_data_name(enum AVFrameSideDataType type)
     case AV_FRAME_DATA_SKIP_SAMPLES:    return "Skip samples";
     case AV_FRAME_DATA_AUDIO_SERVICE_TYPE:          return "Audio service type";
     case AV_FRAME_DATA_MASTERING_DISPLAY_METADATA:  return "Mastering display metadata";
+    case AV_FRAME_DATA_CONTENT_LIGHT_LEVEL:         return "Content light level metadata";
     case AV_FRAME_DATA_GOP_TIMECODE:                return "GOP timecode";
     }
     return NULL;
diff --git a/libavutil/frame.h b/libavutil/frame.h
index 7cb78a1a44..4d8c1bed4f 100644
--- a/libavutil/frame.h
+++ b/libavutil/frame.h
@@ -127,6 +127,12 @@ enum AVFrameSideDataType {
      * libavutil/spherical.h.
      */
     AV_FRAME_DATA_SPHERICAL,
+
+    /**
+     * Content light level (based on CTA-861.3). This payload contains data in
+     * the form of the AVContentLightMetadata struct.
+     */
+    AV_FRAME_DATA_CONTENT_LIGHT_LEVEL,
 };
 
 enum AVActiveFormatDescription {
diff --git a/libavutil/mastering_display_metadata.c b/libavutil/mastering_display_metadata.c
index e1683e55c7..6069347617 100644
--- a/libavutil/mastering_display_metadata.c
+++ b/libavutil/mastering_display_metadata.c
@@ -41,3 +41,26 @@ AVMasteringDisplayMetadata *av_mastering_display_metadata_create_side_data(AVFra
 
     return (AVMasteringDisplayMetadata *)side_data->data;
 }
+
+AVContentLightMetadata *av_content_light_metadata_alloc(size_t *size)
+{
+    AVContentLightMetadata *metadata = av_mallocz(sizeof(AVContentLightMetadata));
+
+    if (size)
+        *size = sizeof(*metadata);
+
+    return metadata;
+}
+
+AVContentLightMetadata *av_content_light_metadata_create_side_data(AVFrame *frame)
+{
+    AVFrameSideData *side_data = av_frame_new_side_data(frame,
+                                                        AV_FRAME_DATA_CONTENT_LIGHT_LEVEL,
+                                                        sizeof(AVContentLightMetadata));
+    if (!side_data)
+        return NULL;
+
+    memset(side_data->data, 0, sizeof(AVContentLightMetadata));
+
+    return (AVContentLightMetadata *)side_data->data;
+}
diff --git a/libavutil/mastering_display_metadata.h b/libavutil/mastering_display_metadata.h
index 936533fec4..847b0b62c6 100644
--- a/libavutil/mastering_display_metadata.h
+++ b/libavutil/mastering_display_metadata.h
@@ -86,4 +86,43 @@ AVMasteringDisplayMetadata *av_mastering_display_metadata_alloc(void);
  */
 AVMasteringDisplayMetadata *av_mastering_display_metadata_create_side_data(AVFrame *frame);
 
+/**
+ * Content light level needed by to transmit HDR over HDMI (CTA-861.3).
+ *
+ * To be used as payload of a AVFrameSideData or AVPacketSideData with the
+ * appropriate type.
+ *
+ * @note The struct should be allocated with av_content_light_metadata_alloc()
+ *       and its size is not a part of the public ABI.
+ */
+typedef struct AVContentLightMetadata {
+    /**
+     * Max content light level (cd/m^2).
+     */
+    unsigned MaxCLL;
+
+    /**
+     * Max average light level per frame (cd/m^2).
+     */
+    unsigned MaxFALL;
+} AVContentLightMetadata;
+
+/**
+ * Allocate an AVContentLightMetadata structure and set its fields to
+ * default values. The resulting struct can be freed using av_freep().
+ *
+ * @return An AVContentLightMetadata filled with default values or NULL
+ *         on failure.
+ */
+AVContentLightMetadata *av_content_light_metadata_alloc(size_t *size);
+
+/**
+ * Allocate a complete AVContentLightMetadata and add it to the frame.
+ *
+ * @param frame The frame which side data is added to.
+ *
+ * @return The AVContentLightMetadata structure to be filled by caller.
+ */
+AVContentLightMetadata *av_content_light_metadata_create_side_data(AVFrame *frame);
+
 #endif /* AVUTIL_MASTERING_DISPLAY_METADATA_H */
diff --git a/libavutil/version.h b/libavutil/version.h
index b0f9ba4f4e..95e1e929f3 100644
--- a/libavutil/version.h
+++ b/libavutil/version.h
@@ -79,7 +79,7 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR  55
-#define LIBAVUTIL_VERSION_MINOR  59
+#define LIBAVUTIL_VERSION_MINOR  60
 #define LIBAVUTIL_VERSION_MICRO 100
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
-- 
2.11.1