Read (display) aspect ratio from mxf files.

Fixes ticket #4107.

libavformat/avformat.h

@@ -1103,6 +1103,13 @@ typedef struct AVStream {
      * Keys are separated from values by '='.
      */
     char *recommended_encoder_configuration;
+
+    /**
+     * display aspect ratio (0 if unknown)
+     * - encoding: unused
+     * - decoding: Set by libavformat to calculate sample_aspect_ratio internally
+     */
+    AVRational display_aspect_ratio;
 } AVStream;
 
 AVRational av_stream_get_r_frame_rate(const AVStream *s);

libavformat/mxfdec.c

@@ -1781,6 +1781,8 @@ static int mxf_parse_structural_metadata(MXFContext *mxf)
             if (source_track->sequence->origin) {
                 av_dict_set_int(&st->metadata, "source_track_origin", source_track->sequence->origin, 0);
             }
+            if (descriptor->aspect_ratio.num && descriptor->aspect_ratio.den)
+                st->display_aspect_ratio = descriptor->aspect_ratio;
         } else if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO) {
             container_ul = mxf_get_codec_ul(mxf_sound_essence_container_uls, essence_container_ul);
             /* Only overwrite existing codec ID if it is unset or A-law, which is the default according to SMPTE RP 224. */

libavformat/utils.c

@@ -3347,6 +3347,11 @@ int avformat_find_stream_info(AVFormatContext *ic, AVDictionary **options)
                     st->r_frame_rate.den = st->time_base.num;
                 }
             }
+            if (st->display_aspect_ratio.num && st->display_aspect_ratio.den) {
+                AVRational hw_ratio = { st->codec->height, st->codec->width };
+                st->sample_aspect_ratio = av_mul_q(st->display_aspect_ratio,
+                                                   hw_ratio);
+            }
         } else if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO) {
             if (!st->codec->bits_per_coded_sample)
                 st->codec->bits_per_coded_sample =