avformat/riff: add m704

(Ticket 2616)

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/riff.c

@@ -170,6 +170,7 @@ const AVCodecTag ff_codec_bmp_tags[] = {
     /* Matrox MPEG-2 intra-only */
     { AV_CODEC_ID_MPEG2VIDEO,   MKTAG('M', '7', '0', '1') },
     { AV_CODEC_ID_MPEG2VIDEO,   MKTAG('M', '7', '0', '3') },
+    { AV_CODEC_ID_MPEG2VIDEO,   MKTAG('M', '7', '0', '4') },
     { AV_CODEC_ID_MPEG2VIDEO,   MKTAG('M', '7', '0', '5') },
     { AV_CODEC_ID_MPEG2VIDEO,   MKTAG('m', 'p', 'g', 'v') },
     { AV_CODEC_ID_MPEG1VIDEO,   MKTAG('B', 'W', '1', '0') },