avcodec/h2645_sei: add support for Ambient Viewing Environment SEI

Defined by H.274, this SEI message is utilized by iPhones to save
the nominal ambient viewing environment for the display of recorded
HDR content. The contents of the message are exposed to API users
as AVFrame side data containing AVAmbientViewingEnvironment.

As the DV RPU test sample is from an iPhone and includes Ambient
Viewing Environment SEI messages, its test result gets updated.

libavcodec/h2645_sei.c

@@ -25,6 +25,7 @@
 
 #include "config_components.h"
 
+#include "libavutil/ambient_viewing_environment.h"
 #include "libavutil/display.h"
 #include "libavutil/film_grain_params.h"
 #include "libavutil/pixdesc.h"
@@ -320,6 +321,31 @@ static int decode_alternative_transfer(H2645SEIAlternativeTransfer *s,
     return 0;
 }
 
+static int decode_ambient_viewing_environment(H2645SEIAmbientViewingEnvironment *s,
+                                              GetByteContext *gb)
+{
+    static const uint16_t max_ambient_light_value = 50000;
+
+    if (bytestream2_get_bytes_left(gb) < 8)
+        return AVERROR_INVALIDDATA;
+
+    s->ambient_illuminance = bytestream2_get_be32u(gb);
+    if (!s->ambient_illuminance)
+        return AVERROR_INVALIDDATA;
+
+    s->ambient_light_x = bytestream2_get_be16u(gb);
+    if (s->ambient_light_x > max_ambient_light_value)
+        return AVERROR_INVALIDDATA;
+
+    s->ambient_light_y = bytestream2_get_be16u(gb);
+    if (s->ambient_light_y > max_ambient_light_value)
+        return AVERROR_INVALIDDATA;
+
+    s->present = 1;
+
+    return 0;
+}
+
 static int decode_film_grain_characteristics(H2645SEIFilmGrainCharacteristics *h,
                                              enum AVCodecID codec_id, GetBitContext *gb)
 {
@@ -383,6 +409,9 @@ int ff_h2645_sei_message_decode(H2645SEI *h, enum SEIType type,
         return decode_frame_packing_arrangement(&h->frame_packing, gb, codec_id);
     case SEI_TYPE_ALTERNATIVE_TRANSFER_CHARACTERISTICS:
         return decode_alternative_transfer(&h->alternative_transfer, gbyte);
+    case SEI_TYPE_AMBIENT_VIEWING_ENVIRONMENT:
+        return decode_ambient_viewing_environment(&h->ambient_viewing_environment,
+                                                  gbyte);
     default:
         return FF_H2645_SEI_MESSAGE_UNHANDLED;
     }
@@ -609,6 +638,20 @@ int ff_h2645_sei_to_frame(AVFrame *frame, H2645SEI *sei,
             avctx->properties |= FF_CODEC_PROPERTY_FILM_GRAIN;
     }
 
+    if (sei->ambient_viewing_environment.present) {
+        H2645SEIAmbientViewingEnvironment *env =
+            &sei->ambient_viewing_environment;
+
+        AVAmbientViewingEnvironment *dst_env =
+            av_ambient_viewing_environment_create_side_data(frame);
+        if (!dst_env)
+            return AVERROR(ENOMEM);
+
+        dst_env->ambient_illuminance = av_make_q(env->ambient_illuminance, 10000);
+        dst_env->ambient_light_x     = av_make_q(env->ambient_light_x,     50000);
+        dst_env->ambient_light_y     = av_make_q(env->ambient_light_y,     50000);
+    }
+
     return 0;
 }
 
@@ -622,4 +665,6 @@ void ff_h2645_sei_reset(H2645SEI *s)
     av_freep(&s->unregistered.buf_ref);
     av_buffer_unref(&s->dynamic_hdr_plus.info);
     av_buffer_unref(&s->dynamic_hdr_vivid.info);
+
+    s->ambient_viewing_environment.present = 0;
 }

libavcodec/h2645_sei.h

@@ -76,6 +76,13 @@ typedef struct H2645SEIAlternativeTransfer {
     int preferred_transfer_characteristics;
 } H2645SEIAlternativeTransfer;
 
+typedef struct H2645SEIAmbientViewingEnvironment {
+    int present;
+    uint32_t ambient_illuminance;
+    uint16_t ambient_light_x;
+    uint16_t ambient_light_y;
+} H2645SEIAmbientViewingEnvironment;
+
 typedef struct H2645SEIFilmGrainCharacteristics {
     int present;
     int model_id;
@@ -108,6 +115,7 @@ typedef struct H2645SEI {
     H2645SEIDisplayOrientation display_orientation;
     H2645SEIAlternativeTransfer alternative_transfer;
     H2645SEIFilmGrainCharacteristics film_grain_characteristics;
+    H2645SEIAmbientViewingEnvironment ambient_viewing_environment;
 } H2645SEI;
 
 enum {

tests/ref/fate/hevc-dv-rpu

@@ -3,6 +3,12 @@
 side_data_type=H.26[45] User Data Unregistered SEI message
 [/SIDE_DATA]
 [SIDE_DATA]
+side_data_type=Ambient viewing environment
+ambient_illuminance=3140000/10000
+ambient_light_x=15635/50000
+ambient_light_y=16450/50000
+[/SIDE_DATA]
+[SIDE_DATA]
 side_data_type=Dolby Vision RPU Data
 [/SIDE_DATA]
 [SIDE_DATA]
@@ -120,6 +126,12 @@ source_diagonal=42
 [/FRAME]
 [FRAME]
 [SIDE_DATA]
+side_data_type=Ambient viewing environment
+ambient_illuminance=3140000/10000
+ambient_light_x=15635/50000
+ambient_light_y=16450/50000
+[/SIDE_DATA]
+[SIDE_DATA]
 side_data_type=Dolby Vision RPU Data
 [/SIDE_DATA]
 [SIDE_DATA]