Add EBML ID for Segment UID

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@9814 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

libavformat/matroska.h

@@ -64,6 +64,7 @@
 #define MATROSKA_ID_WRITINGAPP 0x5741
 #define MATROSKA_ID_MUXINGAPP  0x4D80
 #define MATROSKA_ID_DATEUTC    0x4461
+#define MATROSKA_ID_SEGMENTUID 0x73A4
 
 /* ID in the tracks master */
 #define MATROSKA_ID_TRACKENTRY 0xAE