demux_mkv: propagate global stream side data via codecpar

The first AVPacket method has been deprecated in FFmpeg, and only
the HEVC decoder would read this information from there. The native
AV1 decoder as well as the libdav1d wrapper only support the newer
propagation method via codec context's side data. {ad,sd,vd}_lavc
call mp_set_avctx_codec_headers which copies the side data from
codecpar to codec context, so no changes are required on the
receiving end.

demux/demux_mkv.c

@@ -1688,7 +1688,34 @@ static int demux_mkv_open_video(demuxer_t *demuxer, mkv_track_t *track)
         sh_v->rotate = rotate;
     }
 
+    // our vessel to transport global track side data to decoder context;
+    // this gets called in all lavc decoders through `mp_set_avctx_codec_headers`
+    // and its failure causes decoding failure. Thus if this call fails here, it is
+    // likely that decoding of this track would also lead to an error.
+    sh_v->lav_codecpar = mp_codec_params_to_av(sh_v);
+    if (!sh_v->lav_codecpar) {
+        MP_ERR(demuxer, "Failed to create codec parameters for track %d!",
+               track->tnum);
+        goto done;
+    }
+
     if (track->dovi_config) {
+        size_t dovi_size;
+        AVDOVIDecoderConfigurationRecord *dovi = av_dovi_alloc(&dovi_size);
+        MP_HANDLE_OOM(dovi);
+
+        memcpy(dovi, track->dovi_config, dovi_size);
+
+        if (!av_packet_side_data_add(&sh_v->lav_codecpar->coded_side_data,
+                                     &sh_v->lav_codecpar->nb_coded_side_data,
+                                     AV_PKT_DATA_DOVI_CONF,
+                                     dovi, dovi_size, 0))
+        {
+            MP_ERR(demuxer, "Failed to attach Dolby Vision configuration record to "
+                   "codec parameters for track %d!\n", track->tnum);
+            av_free(dovi);
+        }
+
         sh_v->dovi = true;
         sh_v->dv_level = track->dovi_config->dv_level;
         sh_v->dv_profile = track->dovi_config->dv_profile;
@@ -2997,18 +3024,6 @@ static int handle_block(demuxer_t *demuxer, struct block_info *block_info)
                         add->block_additional.start, add->block_additional.len);
                 }
             }
-            if (track->dovi_config) {
-                size_t dovi_size;
-                AVDOVIDecoderConfigurationRecord *dovi = av_dovi_alloc(&dovi_size);
-                MP_HANDLE_OOM(dovi);
-                memcpy(dovi, track->dovi_config, dovi_size);
-                if (av_packet_add_side_data(dp->avpacket,
-                                            AV_PKT_DATA_DOVI_CONF,
-                                            (uint8_t *)dovi, dovi_size) < 0)
-                {
-                    av_free(dovi);
-                }
-            }
 
             mkv_parse_and_add_packet(demuxer, track, dp);
             talloc_free_children(track->parser_tmp);