Fix timestamps in transmuxed output

Timestamps should not change during transmuxing. Until videojs/mux.js#168 is solved, we work around the Transmuxer's timestamp manipulation by setting an explicit base time. Closes #1102 Change-Id: I92658d795797013a6e962b1e4bc4c712edfd50fc
shaka-project · Nov 7, 2017 · bde4c45 · bde4c45
1 parent 7d23729
commit bde4c45
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Showing 4 changed files with 97 additions and 53 deletions.
diff --git a/externs/mux.js b/externs/mux.js
@@ -37,6 +37,12 @@ muxjs.mp4 = {};
 muxjs.mp4.Transmuxer = function() {};
 
 
+/**
+ * @param {number} time
+ */
+muxjs.mp4.Transmuxer.prototype.setBaseMediaDecodeTime = function(time) {};
+
+
 /**
  * @param {!Uint8Array} data
  */
@@ -62,6 +68,12 @@ muxjs.mp4.Transmuxer.prototype.on = function(type, listener) {};
 muxjs.mp4.Transmuxer.prototype.off = function(type, listener) {};
 
 
+/**
+ * Remove all handlers and clean up.
+ */
+muxjs.mp4.Transmuxer.prototype.dispose = function() {};
+
+
 /**
  * @typedef {{
  *   initSegment: !Uint8Array,

diff --git a/lib/media/media_source_engine.js b/lib/media/media_source_engine.js
@@ -435,10 +435,11 @@ shaka.media.MediaSourceEngine.prototype.getBuffered_ = function(contentType) {
 shaka.media.MediaSourceEngine.prototype.appendBuffer =
     function(contentType, data, startTime, endTime) {
   var ContentType = shaka.util.ManifestParserUtils.ContentType;
+
   if (contentType == ContentType.TEXT) {
     return this.textEngine_.appendBuffer(data, startTime, endTime);
   } else if (this.transmuxers_[contentType]) {
-    return this.transmuxers_[contentType].transmux(data).then(
+    return this.transmuxers_[contentType].transmux(data, startTime).then(
         function(transmuxedData) {
           return this.enqueueOperation_(contentType,
               this.append_.bind(this, contentType, transmuxedData.buffer));

diff --git a/lib/media/transmuxer.js b/lib/media/transmuxer.js
@@ -46,36 +46,25 @@ shaka.media.Transmuxer = function() {
   /** @private {boolean} */
   this.isTransmuxing_ = false;
 
-  this.onTransmuxed_ = this.onTransmuxed_.bind(this);
-
-  this.onTransmuxDone_ = this.onTransmuxDone_.bind(this);
+  /** @private {boolean} */
+  this.baseDecodeTimeSet_ = false;
 
-  this.muxTransmuxer_.on('data', this.onTransmuxed_);
+  this.muxTransmuxer_.on('data', this.onTransmuxed_.bind(this));
 
-  this.muxTransmuxer_.on('done', this.onTransmuxDone_);
+  this.muxTransmuxer_.on('done', this.onTransmuxDone_.bind(this));
 };
 
 
 /**
  * @override
  */
 shaka.media.Transmuxer.prototype.destroy = function() {
-  this.cleanUpListeners_();
+  this.muxTransmuxer_.dispose();
   this.muxTransmuxer_ = null;
   return Promise.resolve();
 };
 
 
-/**
- * Detaches all event listeners.
- * @private
- */
-shaka.media.Transmuxer.prototype.cleanUpListeners_ = function() {
-  this.muxTransmuxer_.off('data', this.onTransmuxed_);
-  this.muxTransmuxer_.off('done', this.onTransmuxDone_);
-};
-
-
 /**
  * Check if the content type is Transport Stream, and if muxjs is loaded.
  * @param {string} contentType
@@ -118,14 +107,23 @@ shaka.media.Transmuxer.convertTsCodecs = function(contentType, tsMimeType) {
 /**
  * Transmux from Transport stream to MP4, using mux.js library.
  * @param {!ArrayBuffer} data
+ * @param {?number} startTime
  * @return {!Promise.<!Uint8Array>}
  */
-shaka.media.Transmuxer.prototype.transmux = function(data) {
+shaka.media.Transmuxer.prototype.transmux = function(data, startTime) {
   goog.asserts.assert(!this.isTransmuxing_,
       'No transmuxing should be in progress.');
   this.isTransmuxing_ = true;
   this.transmuxPromise_ = new shaka.util.PublicPromise();
   this.transmuxedData_ = [];
+
+  // TODO: remove this once videojs/mux.js#168 is solved
+  if (startTime != null && !this.baseDecodeTimeSet_) {
+    var timescale = shaka.media.Transmuxer.TS_TIMESCALE_;
+    this.muxTransmuxer_.setBaseMediaDecodeTime(startTime * timescale);
+    this.baseDecodeTimeSet_ = true;
+  }
+
   var dataArray = new Uint8Array(data);
   this.muxTransmuxer_.push(dataArray);
   this.muxTransmuxer_.flush();
@@ -156,7 +154,15 @@ shaka.media.Transmuxer.prototype.onTransmuxed_ = function(segment) {
  * @private
  */
 shaka.media.Transmuxer.prototype.onTransmuxDone_ = function() {
-  this.transmuxPromise_.resolve(
-      shaka.util.Uint8ArrayUtils.concat.apply(null, this.transmuxedData_));
+  var output =
+      shaka.util.Uint8ArrayUtils.concat.apply(null, this.transmuxedData_);
+  this.transmuxPromise_.resolve(output);
   this.isTransmuxing_ = false;
 };
+
+
+/**
+ * @const {number}
+ * @private
+ */
+shaka.media.Transmuxer.TS_TIMESCALE_ = 90000;
diff --git a/test/media/transmuxer_integration.js b/test/media/transmuxer_integration.js
@@ -86,48 +86,73 @@ describe('Transmuxer', function() {
   describe('transmuxing', function() {
     it('transmux video from TS to MP4', function(done) {
       var sawMDAT = false;
-      transmuxer.transmux(videoSegment).then(
-          function(transmuxedData) {
-            expect(transmuxedData instanceof Uint8Array).toBe(true);
-            expect(transmuxedData.length).toBeGreaterThan(0);
-            new shaka.util.Mp4Parser()
-                .box('mdat', shaka.util.Mp4Parser.allData(function(data) {
-                  sawMDAT = true;
-                  expect(data.buffer.byteLength).toBeGreaterThan(0);
-                }.bind(this))).parse(transmuxedData.buffer);
-            expect(sawMDAT).toBeTruthy();
-          }).catch(fail).then(done);
+      transmuxer.transmux(videoSegment, 0).then(function(transmuxedData) {
+        expect(transmuxedData instanceof Uint8Array).toBe(true);
+        expect(transmuxedData.length).toBeGreaterThan(0);
+        new shaka.util.Mp4Parser()
+            .box('mdat', shaka.util.Mp4Parser.allData(function(data) {
+              sawMDAT = true;
+              expect(data.buffer.byteLength).toBeGreaterThan(0);
+            }))
+            .parse(transmuxedData.buffer);
+        expect(sawMDAT).toBeTruthy();
+      }).catch(fail).then(done);
     });
 
     it('transmux audio from TS to MP4', function(done) {
       var sawMDAT = false;
-      transmuxer.transmux(audioSegment).then(
-          function(transmuxedData) {
-            expect(transmuxedData instanceof Uint8Array).toBe(true);
-            expect(transmuxedData.length).toBeGreaterThan(0);
-            new shaka.util.Mp4Parser()
-                .box('mdat', shaka.util.Mp4Parser.allData(function(data) {
-                  sawMDAT = true;
-                  expect(data.buffer.byteLength).toBeGreaterThan(0);
-                }.bind(this))).parse(transmuxedData.buffer);
-            expect(sawMDAT).toBeTruthy();
-
-          }).catch(fail).then(done);
+      transmuxer.transmux(audioSegment, 0).then(function(transmuxedData) {
+        expect(transmuxedData instanceof Uint8Array).toBe(true);
+        expect(transmuxedData.length).toBeGreaterThan(0);
+        new shaka.util.Mp4Parser()
+            .box('mdat', shaka.util.Mp4Parser.allData(function(data) {
+              sawMDAT = true;
+              expect(data.buffer.byteLength).toBeGreaterThan(0);
+            }))
+            .parse(transmuxedData.buffer);
+        expect(sawMDAT).toBeTruthy();
+      }).catch(fail).then(done);
     });
 
     it('transmux empty video from TS to MP4', function(done) {
       var sawMDAT = false;
-      transmuxer.transmux(emptySegment).then(
-          function(transmuxedData) {
-            expect(transmuxedData instanceof Uint8Array).toBe(true);
-            expect(transmuxedData.length).toBeGreaterThan(0);
-            new shaka.util.Mp4Parser()
-                .box('mdat', shaka.util.Mp4Parser.allData(function(data) {
-                  sawMDAT = true;
-                }.bind(this))).parse(transmuxedData.buffer);
-            expect(sawMDAT).toBeFalsy();
-          }).catch(fail).then(done);
+      transmuxer.transmux(emptySegment, 0).then(function(transmuxedData) {
+        expect(transmuxedData instanceof Uint8Array).toBe(true);
+        expect(transmuxedData.length).toBeGreaterThan(0);
+        new shaka.util.Mp4Parser()
+            .box('mdat', shaka.util.Mp4Parser.allData(function(data) {
+              sawMDAT = true;
+            }))
+            .parse(transmuxedData.buffer);
+        expect(sawMDAT).toBeFalsy();
+      }).catch(fail).then(done);
     });
 
+    it('offsets output timestamps', function(done) {
+      var parsed = false;
+      var expectedMp4Timestamp = 123 * 90000;  // timescale units
+      var mp4Timestamp;
+
+      transmuxer.transmux(videoSegment, 123).then(function(transmuxedData) {
+        var Mp4Parser = shaka.util.Mp4Parser;
+
+        new Mp4Parser()
+            .box('moof', Mp4Parser.children)
+            .box('traf', Mp4Parser.children)
+            .fullBox('tfdt', function(box) {
+              goog.asserts.assert(
+                  box.version == 0 || box.version == 1,
+                  'TFDT version can only be 0 or 1');
+              mp4Timestamp = (box.version == 0) ?
+                  box.reader.readUint32() :
+                  box.reader.readUint64();
+              parsed = true;
+            })
+            .parse(transmuxedData.buffer);
+
+        expect(parsed).toBe(true);
+        expect(mp4Timestamp).toEqual(expectedMp4Timestamp);
+      }).catch(fail).then(done);
+    });
   });
 });