[FFmpeg-devel] [PATCH] lavc/hevc Parse SEI_TYPE_MASTERING_DISPLAY_INFO and propagate contents into the AVMasteringDisplayMetadata side data.

[Neil Birkbeck]

Add support for parsing SEI_TYPE_MASTERING_DISPLAY_INFO and propagate contents into 
the AVMasteringDisplayMetadata side data. Primaries are ordered in RGB order and
the values are converted to the natural ranges ([0,1] for CEI 1931 Chroma coords,
and cd/m^2 for luma).

Signed-off-by: Neil Birkbeck <neil.birkbeck at gmail.com>
---
 libavcodec/hevc.c     | 38 ++++++++++++++++++++++++++++++++++++++
 libavcodec/hevc.h     |  7 +++++++
 libavcodec/hevc_sei.c | 22 ++++++++++++++++++++++
 3 files changed, 67 insertions(+)

diff --git a/libavcodec/hevc.c b/libavcodec/hevc.c
index c245d3b..98cc6f7 100644
--- a/libavcodec/hevc.c
+++ b/libavcodec/hevc.c
@@ -28,6 +28,7 @@
 #include "libavutil/common.h"
 #include "libavutil/display.h"
 #include "libavutil/internal.h"
+#include "libavutil/mastering_display_metadata.h"
 #include "libavutil/md5.h"
 #include "libavutil/opt.h"
 #include "libavutil/pixdesc.h"
@@ -2580,6 +2581,43 @@ static int set_side_data(HEVCContext *s)
                                s->sei_hflip, s->sei_vflip);
     }
 
+    if (s->sei_mastering_display_info_present) {
+        // HEVC uses a g,b,r ordering, which we convert to a more natural r,g,b
+        const int mapping[3] = {2, 0, 1};
+        const float chroma_scale = 50000.f;
+        const float luma_scale = 10000.f;
+        int i;
+        AVMasteringDisplayMetadata *metadata =
+            av_mastering_display_metadata_create_side_data(out);
+        if (!metadata)
+            return AVERROR(ENOMEM);
+
+        for (i = 0; i < 3; i++) {
+            const int j = mapping[i];
+            metadata->display_primaries[i][0] =
+                s->display_primaries[j][0] / chroma_scale;
+            metadata->display_primaries[i][1] =
+                s->display_primaries[j][1] / chroma_scale;
+        }
+        metadata->white_point[0] = s->white_point[0] / chroma_scale;
+        metadata->white_point[1] = s->white_point[1] / chroma_scale;
+        metadata->max_luminance = s->max_mastering_luminance / luma_scale;
+        metadata->min_luminance = s->min_mastering_luminance / luma_scale;
+        metadata->has_luminance = 1;
+        metadata->has_primaries = 1;
+
+        av_log(s->avctx, AV_LOG_DEBUG, "Mastering Display Metadata:\n");
+        av_log(s->avctx, AV_LOG_DEBUG,
+               "r(%5.4f,%5.4f) g(%5.4f,%5.4f) b(%5.4f %5.4f) wp(%5.4f, %5.4f)\n",
+               metadata->display_primaries[0][0], metadata->display_primaries[0][1],
+               metadata->display_primaries[1][0], metadata->display_primaries[1][1],
+               metadata->display_primaries[2][0], metadata->display_primaries[2][1],
+               metadata->white_point[0], metadata->white_point[1]);
+        av_log(s->avctx, AV_LOG_DEBUG,
+               "min_luminance=%f, max_luminance=%f\n",
+               metadata->min_luminance, metadata->max_luminance);
+    }
+
     if (s->a53_caption) {
         AVFrameSideData* sd = av_frame_new_side_data(out,
                                                      AV_FRAME_DATA_A53_CC,
diff --git a/libavcodec/hevc.h b/libavcodec/hevc.h
index 9d72555..c64b94d 100644
--- a/libavcodec/hevc.h
+++ b/libavcodec/hevc.h
@@ -936,6 +936,13 @@ typedef struct HEVCContext {
     int sei_anticlockwise_rotation;
     int sei_hflip, sei_vflip;
 
+    /** mastering display */
+    int sei_mastering_display_info_present;
+    int display_primaries[3][2];
+    int white_point[2];
+    int max_mastering_luminance;
+    int min_mastering_luminance;
+
     int picture_struct;
 
     uint8_t* a53_caption;
diff --git a/libavcodec/hevc_sei.c b/libavcodec/hevc_sei.c
index 07856f2..095c658 100644
--- a/libavcodec/hevc_sei.c
+++ b/libavcodec/hevc_sei.c
@@ -78,6 +78,26 @@ static int decode_nal_sei_decoded_picture_hash(HEVCContext *s)
     return 0;
 }
 
+static int decode_nal_sei_mastering_display_info(HEVCContext *s)
+{
+    GetBitContext *gb = &s->HEVClc->gb;
+    int i;
+    // Mastering primaries
+    for (i = 0; i < 3; i++) {
+        s->display_primaries[i][0] = get_bits(gb, 16);
+        s->display_primaries[i][1] = get_bits(gb, 16);
+    }
+    // White point (x, y)
+    s->white_point[0] = get_bits(gb, 16);
+    s->white_point[1] = get_bits(gb, 16);
+
+    // Max and min luminance of mastering display
+    s->max_mastering_luminance = get_bits(gb, 32);
+    s->min_mastering_luminance = get_bits(gb, 32);
+    s->sei_mastering_display_info_present = 1;
+    return 0;
+}
+
 static int decode_nal_sei_frame_packing_arrangement(HEVCContext *s)
 {
     GetBitContext *gb = &s->HEVClc->gb;
@@ -278,6 +298,8 @@ static int decode_nal_sei_prefix(HEVCContext *s, int type, int size)
             skip_bits(gb, 8 * size);
             return ret;
         }
+    case SEI_TYPE_MASTERING_DISPLAY_INFO:
+        return decode_nal_sei_mastering_display_info(s);
     case SEI_TYPE_ACTIVE_PARAMETER_SETS:
         active_parameter_sets(s);
         av_log(s->avctx, AV_LOG_DEBUG, "Skipped PREFIX SEI %d\n", type);
-- 
2.7.0.rc3.207.g0ac5344