hevc: Add support for alternative transfer characterics SEI

The use of this SEI is for backward compatibility in HLG HDR systems:
older devices that cannot interpret the "arib-std-b67" transfer will
get the compatible transfer (usually bt709 or bt2020) from the VUI,
while newer devices that can interpret HDR will read the SEI and use
its value instead.

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/libavcodec/hevc_sei.h b/libavcodec/hevc_sei.h
index 5645e4f5de..1b522227ec 100644
--- a/libavcodec/hevc_sei.h
+++ b/libavcodec/hevc_sei.h
@@ -56,6 +56,7 @@ typedef enum {
     HEVC_SEI_TYPE_REGION_REFRESH_INFO                  = 134,
     HEVC_SEI_TYPE_MASTERING_DISPLAY_INFO               = 137,
     HEVC_SEI_TYPE_CONTENT_LIGHT_LEVEL_INFO             = 144,
+    HEVC_SEI_TYPE_ALTERNATIVE_TRANSFER_CHARACTERISTICS = 147,
 } HEVC_SEI_Type;
 
 typedef struct HEVCSEIPictureHash {
@@ -100,6 +101,11 @@ typedef struct HEVCSEIContentLight {
     uint16_t max_pic_average_light_level;
 } HEVCSEIContentLight;
 
+typedef struct HEVCSEIAlternativeTransfer {
+    int present;
+    int preferred_transfer_characteristics;
+} HEVCSEIAlternativeTransfer;
+
 typedef struct HEVCSEIContext {
     HEVCSEIPictureHash picture_hash;
     HEVCSEIFramePacking frame_packing;
@@ -109,6 +115,7 @@ typedef struct HEVCSEIContext {
     HEVCSEIMasteringDisplay mastering_display;
     HEVCSEIContentLight content_light;
     int active_seq_parameter_set_id;
+    HEVCSEIAlternativeTransfer alternative_transfer;
 } HEVCSEIContext;
 
 struct HEVCParamSets;