lavf/mxfdec: Set width to actual coded_width for AVCI50.

Fixes ticket #5029.
Reported and analyzed by videolan trac user HenkDemper in vlc ticket #15762.

libavformat/mxfdec.c

@@ -1145,6 +1145,15 @@ static const MXFCodecUL mxf_intra_only_picture_essence_coding_uls[] = {
     { { 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00 },  0,       AV_CODEC_ID_NONE },
 };
 
+/* actual coded width for AVC-Intra to allow selecting correct SPS/PPS */
+static const MXFCodecUL mxf_intra_only_picture_coded_width[] = {
+    { { 0x06,0x0e,0x2b,0x34,0x04,0x01,0x01,0x0A,0x04,0x01,0x02,0x02,0x01,0x32,0x21,0x01 }, 16, 1440 },
+    { { 0x06,0x0e,0x2b,0x34,0x04,0x01,0x01,0x0A,0x04,0x01,0x02,0x02,0x01,0x32,0x21,0x02 }, 16, 1440 },
+    { { 0x06,0x0e,0x2b,0x34,0x04,0x01,0x01,0x0A,0x04,0x01,0x02,0x02,0x01,0x32,0x21,0x03 }, 16, 1440 },
+    { { 0x06,0x0e,0x2b,0x34,0x04,0x01,0x01,0x0A,0x04,0x01,0x02,0x02,0x01,0x32,0x21,0x04 }, 16, 1440 },
+    { { 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00 },  0,    0 },
+};
+
 static const MXFCodecUL mxf_sound_essence_container_uls[] = {
     // sound essence container uls
     { { 0x06,0x0e,0x2b,0x34,0x04,0x01,0x01,0x01,0x0d,0x01,0x03,0x01,0x02,0x06,0x01,0x00 }, 14, AV_CODEC_ID_PCM_S16LE }, /* BWF Frame wrapped */
@@ -2128,6 +2137,10 @@ static int mxf_parse_structural_metadata(MXFContext *mxf)
                 memcpy(st->codec->extradata, descriptor->extradata, descriptor->extradata_size);
             }
         } else if (st->codec->codec_id == AV_CODEC_ID_H264) {
+            int coded_width = mxf_get_codec_ul(mxf_intra_only_picture_coded_width,
+                                               &descriptor->essence_codec_ul)->id;
+            if (coded_width)
+                st->codec->width = coded_width;
             ret = ff_generate_avci_extradata(st);
             if (ret < 0)
                 return ret;