Set the PTS and DTS for TS timestamp ID3 tags (#115)

The special PRIV frame that specifies the timestamp in raw AAC data would not itself receive a timestamp since it was already parsed when the base timestamp was set. Add special case handling for that ID3 tag so that it does not end up with a cueTime of NaN when picked up by the CoalesceStream in the MP4 transmuxer.

lib/m2ts/metadata-stream.js

@@ -209,6 +209,9 @@ MetadataStream = function(options) {
       frame.key = frame.id;
       if (tagParsers[frame.id]) {
         tagParsers[frame.id](frame);
+
+        // handle the special PRIV frame used to indicate the start
+        // time for raw AAC data
         if (frame.owner === 'com.apple.streaming.transportStreamTimestamp') {
           var
             d = frame.data,
@@ -221,6 +224,14 @@ MetadataStream = function(options) {
           size *= 4;
           size += d[7] & 0x03;
           frame.timeStamp = size;
+          // in raw AAC, all subsequent data will be timestamped based
+          // on the value of this frame
+          // we couldn't have known the appropriate pts and dts before
+          // parsing this ID3 tag so set those values now
+          if (tag.pts === undefined && tag.dts === undefined) {
+            tag.pts = frame.timeStamp;
+            tag.dts = frame.timeStamp;
+          }
           this.trigger('timestamp', frame);
         }
       }

test/metadata-stream.test.js

@@ -511,20 +511,26 @@ QUnit.test('can parse TXXX frames in web worker', function(assert) {
 });
 
 QUnit.test('triggers special event after parsing a timestamp ID3 tag', function() {
-  var array = new Uint8Array(73),
+  var
+    array = new Uint8Array(73),
     streamTimestamp = 'com.apple.streaming.transportStreamTimestamp',
     priv = 'PRIV',
     count = 0,
+    frame,
+    tag,
     metadataStream,
     chunk,
     i;
 
   metadataStream = new mp2t.MetadataStream();
-
-  metadataStream.on('timestamp', function(frame) {
-    QUnit.equal(frame.timeStamp, 900000, 'Initial timestamp fired and calculated correctly');
+  metadataStream.on('timestamp', function(f) {
+    frame = f;
     count += 1;
   });
+  metadataStream.on('data', function(t) {
+    tag = t;
+  });
+
   array[0] = 73;
   array[1] = 68;
   array[2] = 51;
@@ -534,19 +540,20 @@ QUnit.test('triggers special event after parsing a timestamp ID3 tag', function(
   array[70] = 13;
   array[71] = 187;
   array[72] = 160;
-
   for (i = 0; i < priv.length; i++) {
     array[i + 10] = priv.charCodeAt(i);
   }
   for (i = 0; i < streamTimestamp.length; i++) {
     array[i + 20] = streamTimestamp.charCodeAt(i);
   }
-
   chunk = {
     type: 'timed-metadata',
     data: array
   };
 
   metadataStream.push(chunk);
   QUnit.equal(count, 1, 'timestamp event triggered once');
+  QUnit.equal(frame.timeStamp, 900000, 'Initial timestamp fired and calculated correctly');
+  QUnit.equal(tag.pts, 10 * 90e3, 'set tag PTS');
+  QUnit.equal(tag.dts, 10 * 90e3, 'set tag DTS');
 });