Ensure overlapping buffered edges are not interpreted as updates

If the old and new buffered ranges have a shared start or end point, that edge should not be interpreted as a new buffered boundary. Fix up a number of the tests. Some tests are still failing.

@@ -187,20 +187,20 @@
        * active media playlist. When called with a single argument,
        * triggers the playlist loader to asynchronously switch to the
        * specified media playlist. Calling this method while the
-       * loader is in the HAVE_NOTHING or HAVE_MASTER states causes an
-       * error to be emitted but otherwise has no effect.
+       * loader is in the HAVE_NOTHING causes an error to be emitted
+       * but otherwise has no effect.
        * @param playlist (optional) {object} the parsed media playlist
        * object to switch to
        */
       loader.media = function(playlist) {
-        var mediaChange = false;
+        var startingState = loader.state, mediaChange;
         // getter
         if (!playlist) {
           return loader.media_;
         }
 
         // setter
-        if (loader.state === 'HAVE_NOTHING' || loader.state === 'HAVE_MASTER') {
+        if (loader.state === 'HAVE_NOTHING') {
           throw new Error('Cannot switch media playlist from ' + loader.state);
         }
 
@@ -213,7 +213,7 @@
           playlist = loader.master.playlists[playlist];
         }
 
-        mediaChange = playlist.uri !== loader.media_.uri;
+        mediaChange = !loader.media_ || playlist.uri !== loader.media_.uri;
 
         // switch to fully loaded playlists immediately
         if (loader.master.playlists[playlist.uri].endList) {
@@ -258,7 +258,17 @@
           withCredentials: withCredentials
         }, function(error, request) {
           haveMetadata(error, request, playlist.uri);
-          loader.trigger('mediachange');
+
+          if (error) {
+            return;
+          }
+
+          // fire loadedmetadata the first time a media playlist is loaded
+          if (startingState === 'HAVE_MASTER') {
+            loader.trigger('loadedmetadata');
+          } else {
+            loader.trigger('mediachange');
+          }
         });
       };
 
@@ -320,19 +330,13 @@
             loader.master.playlists[loader.master.playlists[i].uri] = loader.master.playlists[i];
           }
 
-          request = xhr({
-            uri: resolveUrl(srcUrl, parser.manifest.playlists[0].uri),
-            withCredentials: withCredentials
-          }, function(error, request) {
-            // pass along the URL specified in the master playlist
-            haveMetadata(error,
-                         request,
-                         parser.manifest.playlists[0].uri);
-            if (!error) {
-              loader.trigger('loadedmetadata');
-            }
-          });
-          return loader.trigger('loadedplaylist');
+          loader.trigger('loadedplaylist');
+          if (!request) {
+            // no media playlist was specifically selected so start
+            // from the first listed one
+            loader.media(parser.manifest.playlists[0]);
+          }
+          return;
         }
 
         // loaded a media playlist
@@ -468,8 +472,8 @@
     }
 
     // the playback position is outside the range of available
-    // segments so return the last one
-    return this.media_.segments.length - 1;
+    // segments so return the length
+    return this.media_.segments.length;
   };
 
   videojs.Hls.PlaylistLoader = PlaylistLoader;

@@ -190,7 +190,8 @@ videojs.Hls.prototype.src = function(src) {
     var updatedPlaylist = this.playlists.media();
 
     if (!updatedPlaylist) {
-      // do nothing before an initial media playlist has been activated
+      // select the initial variant
+      this.playlists.media(this.selectPlaylist());
       return;
     }
 
@@ -254,7 +255,7 @@ videojs.Hls.prototype.handleSourceOpen = function() {
 
 // Returns the array of time range edge objects that were additively
 // modified between two TimeRanges.
-var bufferedAdditions = function(original, update) {
+videojs.Hls.bufferedAdditions_ = function(original, update) {
   var result = [], edges = [],
       i, inOriginalRanges;
 
@@ -271,6 +272,15 @@ var bufferedAdditions = function(original, update) {
     var leftTime, rightTime;
     leftTime = left.start !== undefined ? left.start : left.end;
     rightTime = right.start !== undefined ? right.start : right.end;
+
+    // when two times are equal, ensure the original edge covers the
+    // update
+    if (leftTime === rightTime) {
+      if (left.original) {
+        return left.start !== undefined ? -1 : 1;
+      }
+      return right.start !== undefined ? -1 : 1;
+    }
     return leftTime - rightTime;
   });
 
@@ -349,8 +359,8 @@ videojs.Hls.prototype.setupSourceBuffer_ = function() {
     // annotate the segment with any start and end time information
     // added by the media processing
     segment = segmentInfo.playlist.segments[segmentInfo.mediaIndex];
-    timelineUpdates = bufferedAdditions(segmentInfo.buffered,
-                                        this.tech_.buffered());
+    timelineUpdates = videojs.Hls.bufferedAdditions_(segmentInfo.buffered,
+                                                     this.tech_.buffered());
     timelineUpdates.forEach(function(update) {
       if (update.start !== undefined) {
         segment.start = update.start;
@@ -1112,15 +1122,16 @@ videojs.Hls.prototype.drainBuffer = function(event) {
     this.sourceBuffer.timestampOffset = currentBuffered.end(0);
   }
 
-  // the segment is asynchronously added to the current buffered data
   if (currentBuffered.length) {
-    this.sourceBuffer.videoBuffer_.appendWindowStart = Math.min(this.tech_.currentTime(), currentBuffered.end(0));
-  } else if (this.sourceBuffer.videoBuffer_) {
-    this.sourceBuffer.videoBuffer_.appendWindowStart = 0;
+    // Chrome 45 stalls if appends overlap the playhead
+    this.sourceBuffer.appendWindowStart = Math.min(this.tech_.currentTime(), currentBuffered.end(0));
+  } else {
+    this.sourceBuffer.appendWindowStart = 0;
   }
   this.pendingSegment_ = segmentBuffer.shift();
   this.pendingSegment_.buffered = this.tech_.buffered();
 
+  // the segment is asynchronously added to the current buffered data
   this.sourceBuffer.appendBuffer(bytes);
 };
 

@@ -69,13 +69,16 @@
   });
 
   test('moves to HAVE_MASTER after loading a master playlist', function() {
-    var loader = new videojs.Hls.PlaylistLoader('master.m3u8');
+    var loader = new videojs.Hls.PlaylistLoader('master.m3u8'), state;
+    loader.on('loadedplaylist', function() {
+      state = loader.state;
+    });
     requests.pop().respond(200, null,
                            '#EXTM3U\n' +
                            '#EXT-X-STREAM-INF:\n' +
                            'media.m3u8\n');
     ok(loader.master, 'the master playlist is available');
-    strictEqual(loader.state, 'HAVE_MASTER', 'the state is correct');
+    strictEqual(state, 'HAVE_MASTER', 'the state at loadedplaylist correct');
   });
 
   test('jumps to HAVE_METADATA when initialized with a media playlist', function() {
@@ -453,6 +456,20 @@
                 'updated the active media');
   });
 
+  test('can switch playlists immediately after the master is downloaded', function() {
+    var loader = new videojs.Hls.PlaylistLoader('master.m3u8');
+    loader.on('loadedplaylist', function() {
+      loader.media('high.m3u8');
+    });
+    requests.pop().respond(200, null,
+                           '#EXTM3U\n' +
+                           '#EXT-X-STREAM-INF:BANDWIDTH=1\n' +
+                           'low.m3u8\n' +
+                           '#EXT-X-STREAM-INF:BANDWIDTH=2\n' +
+                           'high.m3u8\n');
+    equal(requests[0].url, urlTo('high.m3u8'), 'switched variants immediately');
+  });
+
   test('can switch media playlists based on URI', function() {
     var loader = new videojs.Hls.PlaylistLoader('master.m3u8');
     requests.pop().respond(200, null,
@@ -624,9 +641,6 @@
                            'low.m3u8\n' +
                            '#EXT-X-STREAM-INF:BANDWIDTH=2\n' +
                            'high.m3u8\n');
-    throws(function() {
-      loader.media('high.m3u8');
-    }, 'throws an error from HAVE_MASTER');
   });
 
   test('throws an error if a switch to an unrecognized playlist is requested', function() {
@@ -757,10 +771,8 @@
                              '#EXTINF:5,\n' +
                              '1.ts\n' +
                              '#EXT-X-ENDLIST\n');
-    equal(loader.getMediaIndexForTime_(4), 0, 'rounds down exact matches');
+    equal(loader.getMediaIndexForTime_(4), 1, 'rounds up exact matches');
     equal(loader.getMediaIndexForTime_(3.7), 0, 'rounds down');
-    // FIXME: the test below should pass for HLSv3
-    //equal(loader.getMediaIndexForTime_(4.2), 0, 'rounds down');
     equal(loader.getMediaIndexForTime_(4.5), 1, 'rounds up at 0.5');
   });