add dvcs to dvvideo, fixes issue 1604

Originally committed as revision 20786 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/riff.c

@@ -102,6 +102,7 @@ const AVCodecTag ff_codec_bmp_tags[] = {
     { CODEC_ID_DVVIDEO,      MKTAG('c', 'd', 'v', 'c') }, /* Canopus DV */
     { CODEC_ID_DVVIDEO,      MKTAG('C', 'D', 'V', 'H') }, /* Canopus DV */
     { CODEC_ID_DVVIDEO,      MKTAG('d', 'v', 'c', ' ') },
+    { CODEC_ID_DVVIDEO,      MKTAG('d', 'v', 'c', 's') },
     { CODEC_ID_DVVIDEO,      MKTAG('d', 'v', 'h', '1') },
     { CODEC_ID_MPEG1VIDEO,   MKTAG('m', 'p', 'g', '1') },
     { CODEC_ID_MPEG1VIDEO,   MKTAG('m', 'p', 'g', '2') },