added styp generator and default audio hdlr box

@@ -33,6 +33,7 @@ DataView = window.DataView;
     stsd: [],
     stsz: [],
     stts: [],
+    styp: [],
     tfhd: [],
     traf: [],
     trak: [],
@@ -71,6 +72,18 @@ DataView = window.DataView;
     0x6f, 0x48, 0x61, 0x6e,
     0x64, 0x6c, 0x65, 0x72, 0x00 // name: 'VideoHandler'
   ]);
+  SOUND_HDLR = new Uint8Array([
+    0x00, // version 0
+    0x00, 0x00, 0x00, // flags
+    0x00, 0x00, 0x00, 0x00, // pre_defined
+    0x73, 0x6f, 0x75, 0x6e, // handler_type: 'soun'
+    0x00, 0x00, 0x00, 0x00, // reserved
+    0x00, 0x00, 0x00, 0x00, // reserved
+    0x00, 0x00, 0x00, 0x00, // reserved
+    0x56, 0x69, 0x64, 0x65,
+    0x6f, 0x48, 0x61, 0x6e,
+    0x73, 0x6f, 0x75, 0x6e, 0x00 // name: 'VideoHandler'
+  ]);
   DREF = new Uint8Array([
     0x00, // version 0
     0x00, 0x00, 0x00, // flags
@@ -296,6 +309,10 @@ stsd = function(width, height) {
         ));
 };
 
+styp = function() {
+  return box(types.styp, MAJOR_BRAND, MINOR_VERSION, MAJOR_BRAND);
+};
+
 tkhd = function(duration, width, height) {
   return box(types.tkhd, new Uint8Array([
     0x00, // version 0