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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>
This commit is contained in:
Vittorio Giovara 2017-06-09 17:27:22 -04:00
parent a594f17f83
commit 969f215957
3 changed files with 22 additions and 0 deletions
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9
libavcodec/hevc_sei.c
View File

@ -86,6 +86,13 @@ static int decode_nal_sei_display_orientation(HEVCSEIDisplayOrientation *s, GetB
return 0;
}
static int decode_nal_sei_alternative_transfer(HEVCSEIAlternativeTransfer *s, GetBitContext *gb)
{
s->present = 1;
s->preferred_transfer_characteristics = get_bits(gb, 8);
return 0;
}
static int decode_nal_sei_prefix(GetBitContext *gb, void *logctx, HEVCSEI *s,
int type, int size)
{
@ -96,6 +103,8 @@ static int decode_nal_sei_prefix(GetBitContext *gb, void *logctx, HEVCSEI *s,
return decode_nal_sei_frame_packing_arrangement(&s->frame_packing, gb);
case HEVC_SEI_TYPE_DISPLAY_ORIENTATION:
return decode_nal_sei_display_orientation(&s->display_orientation, gb);
case HEVC_SEI_TYPE_ALTERNATIVE_TRANSFER_CHARACTERISTICS:
return decode_nal_sei_alternative_transfer(&s->alternative_transfer, gb);
default:
av_log(logctx, AV_LOG_DEBUG, "Skipped PREFIX SEI %d\n", type);
skip_bits_long(gb, 8 * size);

7
libavcodec/hevc_sei.h
View File

@ -54,6 +54,7 @@ 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 {
@ -74,10 +75,16 @@ typedef struct HEVCSEIDisplayOrientation {
int hflip, vflip;
} HEVCSEIDisplayOrientation;
typedef struct HEVCSEIAlternativeTransfer {
int present;
int preferred_transfer_characteristics;
} HEVCSEIAlternativeTransfer;
typedef struct HEVCSEI {
HEVCSEIPictureHash picture_hash;
HEVCSEIFramePacking frame_packing;
HEVCSEIDisplayOrientation display_orientation;
HEVCSEIAlternativeTransfer alternative_transfer;
} HEVCSEI;
int ff_hevc_decode_nal_sei(GetBitContext *gb, void *logctx, HEVCSEI *s,

6
libavcodec/hevcdec.c
View File

@ -2407,6 +2407,12 @@ static int set_side_data(HEVCContext *s)
s->sei.display_orientation.vflip);
}
if (s->sei.alternative_transfer.present &&
av_color_transfer_name(s->sei.alternative_transfer.preferred_transfer_characteristics) &&
s->sei.alternative_transfer.preferred_transfer_characteristics != AVCOL_TRC_UNSPECIFIED) {
s->avctx->color_trc = s->sei.alternative_transfer.preferred_transfer_characteristics;
}
return 0;
}