avcodec/h2645_sei: use the RefStruct API for film_grain_characteristics

And ensure the buffer is synced between threads.
Based on a patch by Dale Curtis <dalecurtis@chromium.org>

Signed-off-by: James Almer <jamrial@gmail.com>

libavcodec/h2645_sei.c

@@ -42,6 +42,7 @@
 #include "golomb.h"
 #include "h2645_sei.h"
 #include "itut35.h"
+#include "refstruct.h"
 
 #define IS_H264(codec_id) (CONFIG_H264_SEI && CONFIG_HEVC_SEI ? codec_id == AV_CODEC_ID_H264 : CONFIG_H264_SEI)
 #define IS_HEVC(codec_id) (CONFIG_H264_SEI && CONFIG_HEVC_SEI ? codec_id == AV_CODEC_ID_HEVC : CONFIG_HEVC_SEI)
@@ -495,7 +496,11 @@ int ff_h2645_sei_message_decode(H2645SEI *h, enum SEIType type,
     case SEI_TYPE_DISPLAY_ORIENTATION:
         return decode_display_orientation(&h->display_orientation, gb);
     case SEI_TYPE_FILM_GRAIN_CHARACTERISTICS:
-        return decode_film_grain_characteristics(&h->film_grain_characteristics, codec_id, gb);
+        ff_refstruct_unref(&h->film_grain_characteristics);
+        h->film_grain_characteristics = ff_refstruct_allocz(sizeof(*h->film_grain_characteristics));
+        if (!h->film_grain_characteristics)
+            return AVERROR(ENOMEM);
+        return decode_film_grain_characteristics(h->film_grain_characteristics, codec_id, gb);
     case SEI_TYPE_FRAME_PACKING_ARRANGEMENT:
         return decode_frame_packing_arrangement(&h->frame_packing, gb, codec_id);
     case SEI_TYPE_ALTERNATIVE_TRANSFER_CHARACTERISTICS:
@@ -551,6 +556,9 @@ int ff_h2645_sei_ctx_replace(H2645SEI *dst, const H2645SEI *src)
     }
     dst->aom_film_grain.enable = src->aom_film_grain.enable;
 
+    ff_refstruct_replace(&dst->film_grain_characteristics,
+                          src->film_grain_characteristics);
+
     return 0;
 }
 
@@ -820,8 +828,8 @@ int ff_h2645_sei_to_frame(AVFrame *frame, H2645SEI *sei,
             return ret;
     }
 
-    if (sei->film_grain_characteristics.present) {
+    if (sei->film_grain_characteristics && sei->film_grain_characteristics->present) {
-        H2645SEIFilmGrainCharacteristics *fgc = &sei->film_grain_characteristics;
+        H2645SEIFilmGrainCharacteristics *fgc = sei->film_grain_characteristics;
         AVFilmGrainParams *fgp = av_film_grain_params_create_side_data(frame);
         AVFilmGrainH274Params *h274;
 
@@ -923,5 +931,6 @@ void ff_h2645_sei_reset(H2645SEI *s)
     s->mastering_display.present = 0;
     s->content_light.present = 0;
 
+    ff_refstruct_unref(&s->film_grain_characteristics);
     ff_aom_uninit_film_grain_params(&s->aom_film_grain);
 }

libavcodec/h2645_sei.h

@@ -135,11 +135,13 @@ typedef struct H2645SEI {
     H2645SEIFramePacking frame_packing;
     H2645SEIDisplayOrientation display_orientation;
     H2645SEIAlternativeTransfer alternative_transfer;
-    H2645SEIFilmGrainCharacteristics film_grain_characteristics;
     H2645SEIAmbientViewingEnvironment ambient_viewing_environment;
     H2645SEIMasteringDisplay mastering_display;
     H2645SEIContentLight content_light;
     AVFilmGrainAFGS1Params aom_film_grain;
+
+    // Dynamic allocations due to large size.
+    H2645SEIFilmGrainCharacteristics *film_grain_characteristics;
 } H2645SEI;
 
 enum {

libavcodec/h264_sei.c

@@ -55,7 +55,6 @@ void ff_h264_sei_uninit(H264SEIContext *h)
     h->picture_timing.present      = 0;
     h->buffering_period.present    = 0;
     h->common.frame_packing.present       = 0;
-    h->common.film_grain_characteristics.present = 0;
     h->common.display_orientation.present = 0;
     h->common.afd.present                 =  0;
 

libavcodec/h264_slice.c

@@ -516,7 +516,10 @@ static int h264_frame_start(H264Context *h)
     pic->f->crop_top    = h->crop_top;
     pic->f->crop_bottom = h->crop_bottom;
 
-    pic->needs_fg = h->sei.common.film_grain_characteristics.present && !h->avctx->hwaccel &&
+    pic->needs_fg =
+        h->sei.common.film_grain_characteristics &&
+        h->sei.common.film_grain_characteristics->present &&
+        !h->avctx->hwaccel &&
         !(h->avctx->export_side_data & AV_CODEC_EXPORT_DATA_FILM_GRAIN);
 
     if ((ret = alloc_picture(h, pic)) < 0)

libavcodec/hevc/hevcdec.c

@@ -412,7 +412,7 @@ static int export_stream_params_from_sei(HEVCContext *s)
         avctx->color_trc = s->sei.common.alternative_transfer.preferred_transfer_characteristics;
     }
 
-    if (s->sei.common.film_grain_characteristics.present ||
+    if ((s->sei.common.film_grain_characteristics && s->sei.common.film_grain_characteristics->present) ||
         s->sei.common.aom_film_grain.enable)
         avctx->properties |= FF_CODEC_PROPERTY_FILM_GRAIN;
 
@@ -3267,7 +3267,8 @@ static int hevc_frame_start(HEVCContext *s, HEVCLayerContext *l,
     else
         s->cur_frame->f->flags &= ~AV_FRAME_FLAG_KEY;
 
-    s->cur_frame->needs_fg = (s->sei.common.film_grain_characteristics.present ||
+    s->cur_frame->needs_fg = ((s->sei.common.film_grain_characteristics &&
+                               s->sei.common.film_grain_characteristics->present) ||
                               s->sei.common.aom_film_grain.enable) &&
         !(s->avctx->export_side_data & AV_CODEC_EXPORT_DATA_FILM_GRAIN) &&
         !s->avctx->hwaccel;
@@ -3277,8 +3278,8 @@ static int hevc_frame_start(HEVCContext *s, HEVCLayerContext *l,
         goto fail;
 
     if (s->cur_frame->needs_fg &&
-        (s->sei.common.film_grain_characteristics.present &&
+        (s->sei.common.film_grain_characteristics && s->sei.common.film_grain_characteristics->present &&
-         !ff_h274_film_grain_params_supported(s->sei.common.film_grain_characteristics.model_id,
+         !ff_h274_film_grain_params_supported(s->sei.common.film_grain_characteristics->model_id,
                                               s->cur_frame->f->format) ||
          !av_film_grain_params_select(s->cur_frame->f))) {
         av_log_once(s->avctx, AV_LOG_WARNING, AV_LOG_DEBUG, &s->film_grain_warning_shown,