avcodec/av1dec: signal new AVFilmGrainParams members

Not directly signalled by AV1, but we should still set this accordingly
so that users will know what the original intended video characteristics
and chroma resolution were.

libavcodec/av1dec.c

@@ -1074,9 +1074,11 @@ static int export_film_grain(AVCodecContext *avctx, AVFrame *frame)
 {
     AV1DecContext *s = avctx->priv_data;
     const AV1RawFilmGrainParams *film_grain = &s->cur_frame.film_grain;
+    const AVPixFmtDescriptor *pixdesc = av_pix_fmt_desc_get(frame->format);
     AVFilmGrainParams *fgp;
     AVFilmGrainAOMParams *aom;
 
+    av_assert0(pixdesc);
     if (!film_grain->apply_grain)
         return 0;
 
@@ -1086,6 +1088,14 @@ static int export_film_grain(AVCodecContext *avctx, AVFrame *frame)
 
     fgp->type = AV_FILM_GRAIN_PARAMS_AV1;
     fgp->seed = film_grain->grain_seed;
+    fgp->width = frame->width;
+    fgp->height = frame->height;
+    fgp->color_range = frame->color_range;
+    fgp->color_primaries = frame->color_primaries;
+    fgp->color_trc = frame->color_trc;
+    fgp->color_space = frame->colorspace;
+    fgp->subsampling_x = pixdesc->log2_chroma_w;
+    fgp->subsampling_y = pixdesc->log2_chroma_h;
 
     aom = &fgp->codec.aom;
     aom->chroma_scaling_from_luma = film_grain->chroma_scaling_from_luma;