[FFmpeg-devel] [PATCH 1/4] avcodec/cbs_{h2645, sei}: add support for Ambient Viewing Environment SEI

[Jan Ekström]

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.
---
 libavcodec/cbs_h2645.c               |  6 ++++++
 libavcodec/cbs_sei.h                 |  6 ++++++
 libavcodec/cbs_sei_syntax_template.c | 17 +++++++++++++++++
 3 files changed, 29 insertions(+)

diff --git a/libavcodec/cbs_h2645.c b/libavcodec/cbs_h2645.c
index 4ee06003c3..80e48829af 100644
--- a/libavcodec/cbs_h2645.c
+++ b/libavcodec/cbs_h2645.c
@@ -1500,6 +1500,12 @@ static const SEIMessageTypeDescriptor cbs_sei_common_types[] = {
         sizeof(SEIRawAlternativeTransferCharacteristics),
         SEI_MESSAGE_RW(sei, alternative_transfer_characteristics),
     },
+    {
+        SEI_TYPE_AMBIENT_VIEWING_ENVIRONMENT,
+        1, 0,
+        sizeof(SEIRawAmbientViewingEnvironment),
+        SEI_MESSAGE_RW(sei, ambient_viewing_environment),
+    },
     SEI_MESSAGE_TYPE_END,
 };
 
diff --git a/libavcodec/cbs_sei.h b/libavcodec/cbs_sei.h
index c7a7a95be0..1c327a4689 100644
--- a/libavcodec/cbs_sei.h
+++ b/libavcodec/cbs_sei.h
@@ -65,6 +65,12 @@ typedef struct SEIRawAlternativeTransferCharacteristics {
     uint8_t preferred_transfer_characteristics;
 } SEIRawAlternativeTransferCharacteristics;
 
+typedef struct SEIRawAmbientViewingEnvironment {
+    uint32_t ambient_illuminance;
+    uint16_t ambient_light_x;
+    uint16_t ambient_light_y;
+} SEIRawAmbientViewingEnvironment;
+
 typedef struct SEIRawMessage {
     uint32_t     payload_type;
     uint32_t     payload_size;
diff --git a/libavcodec/cbs_sei_syntax_template.c b/libavcodec/cbs_sei_syntax_template.c
index 0ef7b42ed9..6a7cc36dda 100644
--- a/libavcodec/cbs_sei_syntax_template.c
+++ b/libavcodec/cbs_sei_syntax_template.c
@@ -144,6 +144,23 @@ static int FUNC(alternative_transfer_characteristics)
     return 0;
 }
 
+static int FUNC(ambient_viewing_environment)
+    (CodedBitstreamContext *ctx, RWContext *rw,
+     SEIRawAmbientViewingEnvironment *current,
+     SEIMessageState *state)
+{
+    static const uint16_t max_ambient_light_value = 50000;
+    int err;
+
+    HEADER("Ambient Viewing Environment");
+
+    u(32, ambient_illuminance, 1, MAX_UINT_BITS(32));
+    u(16, ambient_light_x, 0, max_ambient_light_value);
+    u(16, ambient_light_y, 0, max_ambient_light_value);
+
+    return 0;
+}
+
 static int FUNC(message)(CodedBitstreamContext *ctx, RWContext *rw,
                          SEIRawMessage *current)
 {
-- 
2.39.0