Expose more diagnostic info

Keep track of total content bytes received and make it accessible from outside the tech. Trigger an event whenever a new playlist is activated. For #93.

@@ -116,6 +116,11 @@ The number of bits downloaded per second in the last segment download.
 This value is used by the default implementation of `selectPlaylist` 
 to select an appropriate bitrate to play.
 
+#### player.hls.bytesReceived
+Type: `number`
+
+The total number of content bytes downloaded by the HLS tech.
+
 #### player.hls.selectPlaylist
 Type: `function`
 
@@ -136,6 +141,13 @@ Fired immediately after a new master or media playlist has been
 downloaded. By default, the tech only downloads playlists as they
 are needed.
 
+#### mediachange
+
+Fired when a new playlist becomes the active media playlist. Note that
+the actual rendering quality change does not occur simultaneously with
+this event; a new segment must be requested and the existing buffer
+depleted first.
+
 ### Testing
 
 For testing, you can either run `npm test` or use `grunt` directly.

@@ -131,6 +131,7 @@
        * object to switch to
        */
       loader.media = function(playlist) {
+        var mediaChange = false;
         // getter
         if (!playlist) {
           return media;
@@ -150,19 +151,27 @@
           playlist = loader.master.playlists[playlist];
         }
 
+        mediaChange = playlist.uri !== media.uri;
+
         // switch to fully loaded playlists immediately
         if (loader.master.playlists[playlist.uri].endList) {
+          // abort outstanding playlist requests
           if (request) {
             request.abort();
             request = null;
           }
           loader.state = 'HAVE_METADATA';
           media = playlist;
+
+          // trigger media change if the active media has been updated
+          if (mediaChange) {
+            loader.trigger('mediachange');
+          }
           return;
         }
 
         // switching to the active playlist is a no-op
-        if (playlist.uri === media.uri) {
+        if (!mediaChange) {
           return;
         }
 
@@ -185,6 +194,7 @@
           withCredentials: withCredentials
         }, function(error) {
           haveMetadata(error, this, playlist.uri);
+          loader.trigger('mediachange');
         });
       };
 

@@ -433,6 +433,7 @@ var
         // calculate the download bandwidth
         player.hls.segmentXhrTime = (+new Date()) - startTime;
         player.hls.bandwidth = (this.response.byteLength / player.hls.segmentXhrTime) * 8 * 1000;
+        player.hls.bytesReceived += this.response.byteLength;
 
         // transmux the segment data from MP2T to FLV
         segmentParser.parseSegmentBinaryData(new Uint8Array(this.response));
@@ -575,6 +576,9 @@ var
                                                     updatedPlaylist);
         oldMediaPlaylist = updatedPlaylist;
       });
+      player.hls.playlists.on('mediachange', function() {
+        player.trigger('mediachange');
+      });
     });
   };
 
@@ -591,6 +595,8 @@ videojs.Hls = videojs.Flash.extend({
     options.swf = settings.flash.swf;
     videojs.Flash.call(this, player, options, ready);
     options.source = source;
+    this.bytesReceived = 0;
+
     videojs.Hls.prototype.src.call(this, options.source && options.source.src);
   }
 });

@@ -510,4 +510,45 @@
     strictEqual(errors, 1, 'fired one error');
     strictEqual(loader.error.code, 2, 'fired a network error');
   });
+
+  test('triggers an event when the active media changes', function() {
+    var
+      loader = new videojs.Hls.PlaylistLoader('master.m3u8'),
+      mediaChanges = 0;
+    loader.on('mediachange', function() {
+      mediaChanges++;
+    });
+    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');
+    requests.shift().respond(200, null,
+                             '#EXTM3U\n' +
+                             '#EXT-X-MEDIA-SEQUENCE:0\n' +
+                             '#EXTINF:10,\n' +
+                             'low-0.ts\n' +
+                             '#EXT-X-ENDLIST\n');
+    strictEqual(mediaChanges, 0, 'initial selection is not a media change');
+
+    loader.media('high.m3u8');
+    strictEqual(mediaChanges, 0, 'mediachange does not fire immediately');
+
+    requests.shift().respond(200, null,
+                             '#EXTM3U\n' +
+                             '#EXT-X-MEDIA-SEQUENCE:0\n' +
+                             '#EXTINF:10,\n' +
+                             'high-0.ts\n' +
+                             '#EXT-X-ENDLIST\n');
+    strictEqual(mediaChanges, 1, 'fired a mediachange');
+
+    // switch back to an already loaded playlist
+    loader.media('low.m3u8');
+    strictEqual(mediaChanges, 2, 'fired a mediachange');
+
+    // trigger a no-op switch
+    loader.media('low.m3u8');
+    strictEqual(mediaChanges, 2, 'ignored a no-op media change');
+  });
 })(window);

@@ -1227,4 +1227,55 @@ test('has no effect if native HLS is available', function() {
   player.dispose();
 });
 
+test('tracks the bytes downloaded', function() {
+  player.src({
+    src: 'http://example.com/media.m3u8',
+    type: 'application/vnd.apple.mpegurl'
+  });
+  player.hls.mediaSource.trigger({
+    type: 'sourceopen'
+  });
+
+  strictEqual(player.hls.bytesReceived, 0, 'no bytes received');
+
+  requests.shift().respond(200, null,
+                           '#EXTM3U\n' +
+                           '#EXTINF:10,\n' +
+                           '0.ts\n' +
+                           '#EXTINF:10,\n' +
+                           '1.ts\n' +
+                           '#EXT-X-ENDLIST\n');
+  // transmit some segment bytes
+  requests[0].response = new ArrayBuffer(17);
+  requests.shift().respond(200, null, '');
+
+  strictEqual(player.hls.bytesReceived, 17, 'tracked bytes received');
+
+  player.trigger('timeupdate');
+
+  // transmit some more
+  requests[0].response = new ArrayBuffer(5);
+  requests.shift().respond(200, null, '');
+
+  strictEqual(player.hls.bytesReceived, 22, 'tracked more bytes');
+});
+
+test('re-emits mediachange events', function() {
+  var mediaChanges = 0;
+  player.on('mediachange', function() {
+    mediaChanges++;
+  });
+
+  player.src({
+    src: 'http://example.com/media.m3u8',
+    type: 'application/vnd.apple.mpegurl'
+  });
+  player.hls.mediaSource.trigger({
+    type: 'sourceopen'
+  });
+
+  player.hls.playlists.trigger('mediachange');
+  strictEqual(mediaChanges, 1, 'fired mediachange');
+});
+
 })(window, window.videojs);