mov: handle h263 and flv1 for codec_tag 'H','2','6','3'

The sample in https://bugzilla.libav.org/show_bug.cgi?id=393 and
samples/F4V/H263_NM_f.mp4 both have codec_tag H263 for different
codecs. H263 is apparently used by Flash Media Server for Sorensen
Spark videos.

Patch based on commit 5442083b1c by
Carl Eugen Hoyos. Fixes bug 393.

libavformat/isom.c

@@ -211,7 +211,7 @@ const AVCodecTag ff_codec_movvideo_tags[] = {
 
     { AV_CODEC_ID_DIRAC,     MKTAG('d', 'r', 'a', 'c') },
     { AV_CODEC_ID_DNXHD,     MKTAG('A', 'V', 'd', 'n') }, /* AVID DNxHD */
-    { AV_CODEC_ID_FLV1,      MKTAG('H', '2', '6', '3') }, /* Flash Media Server */
+    { AV_CODEC_ID_H263,      MKTAG('H', '2', '6', '3') },
     { AV_CODEC_ID_MSMPEG4V3, MKTAG('3', 'I', 'V', 'D') }, /* 3ivx DivX Doctor */
     { AV_CODEC_ID_RAWVIDEO,  MKTAG('A', 'V', '1', 'x') }, /* AVID 1:1x */
     { AV_CODEC_ID_RAWVIDEO,  MKTAG('A', 'V', 'u', 'p') },

libavformat/mov.c

@@ -1171,6 +1171,10 @@ int ff_mov_read_stsd_entries(MOVContext *c, AVIOContext *pb, int entries)
             /* codec_tag YV12 triggers an UV swap in rawdec.c */
             if (!memcmp(st->codec->codec_name, "Planar Y'CbCr 8-bit 4:2:0", 25))
                 st->codec->codec_tag=MKTAG('I', '4', '2', '0');
+            /* Flash Media Server uses tag H263 with Sorenson Spark */
+            if (format == MKTAG('H','2','6','3') &&
+                !memcmp(st->codec->codec_name, "Sorenson H263", 13))
+                st->codec->codec_id = AV_CODEC_ID_FLV1;
 
             st->codec->bits_per_coded_sample = avio_rb16(pb); /* depth */
             color_table_id = avio_rb16(pb); /* colortable id */