Add syncpoint_checksum after frame header

git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@17585 b3059339-0415-0410-9bf9-f77b7e298cf2

DOCS/tech/mpcf.txt

@@ -219,6 +219,9 @@ frame:
     }
     for(i=0; i<reserved_count[frame_code]; i++)
         reserved                        v
+    if (after_syncpoint){
+        syncpoint_checksum              u(32)
+    }
     data
 
 index:
@@ -558,6 +561,11 @@ checksum
     including the checksum itself (from first byte after the
     forward_ptr until last byte before the checksum).
 
+syncpoint_checksum
+    crc32 checksum
+    checksum covers from first byte after syncpoint startcode until last 
+    byte before the syncpoint_checksum.
+
 back_ptr_div8
     back_ptr = back_ptr_div8 * 8 + 7
     back_ptr must point to a position within 8 bytes of a syncpoint