Restart switching from the lowest bitrate if a segment times out

When there is a big enough drop in bandwidth that a segment request actually times out, restart the algorithm from the lowest bitrate playlist. Update tech disposal so that oustanding segment XHRs are aborted when the player is cleaned up.

src/videojs-hls.js

@@ -329,6 +329,20 @@ var
       return resolutionBestVariant || bandwidthBestVariant || sortedPlaylists[0];
     };
 
+    /**
+     * Abort all outstanding work and cleanup.
+     */
+    player.hls.dispose = function() {
+      if (segmentXhr) {
+        segmentXhr.onreadystatechange = null;
+        segmentXhr.abort();
+      }
+      if (this.playlists) {
+        this.playlists.dispose();
+      }
+      videojs.Flash.prototype.dispose.call(this);
+    };
+
     /**
      * Determines whether there is enough video data currently in the buffer
      * and downloads a new segment if the buffered time is less than the goal.
@@ -394,6 +408,12 @@ var
         segmentXhr = null;
 
         if (error) {
+          // if a segment request times out, we may have better luck with another playlist
+          if (error === 'timeout') {
+            player.hls.bandwidth = 1;
+            return player.hls.playlists.media(player.hls.selectPlaylist());
+          }
+          // otherwise, try jumping ahead to the next segment
           player.hls.error = {
             status: this.status,
             message: 'HLS segment request error at URL: ' + url,
@@ -607,13 +627,6 @@ videojs.Hls.prototype.duration = function() {
   return 0;
 };
 
-videojs.Hls.prototype.dispose = function() {
-  if (this.playlists) {
-    this.playlists.dispose();
-  }
-  videojs.Flash.prototype.dispose.call(this);
-};
-
 videojs.Hls.isSupported = function() {
   return videojs.Flash.isSupported() && videojs.MediaSource;
 };
@@ -665,10 +678,14 @@ xhr = videojs.Hls.xhr = function(url, callback) {
   if (options.timeout) {
     if (request.timeout === 0) {
       request.timeout = options.timeout;
+      request.ontimeout = function() {
+        request.timedout = true;
+      };
     } else {
       // polyfill XHR2 by aborting after the timeout
       abortTimeout = window.setTimeout(function() {
         if (request.readystate !== 4) {
+          request.timedout = true;
           request.abort();
         }
       }, options.timeout);
@@ -684,7 +701,12 @@ xhr = videojs.Hls.xhr = function(url, callback) {
     // clear outstanding timeouts
     window.clearTimeout(abortTimeout);
 
-    // request error
+    // request timeout
+    if (request.timedout) {
+      return callback.call(this, 'timeout', url);
+    }
+
+    // request aborted or errored
     if (this.status >= 400 || this.status === 0) {
       return callback.call(this, true, url);
     }

test/videojs-hls_test.js

@@ -420,7 +420,6 @@ test('selects a playlist after segment downloads', function() {
   player.trigger('timeupdate');
 
   standardXHRResponse(requests[3]);
-  console.log(requests.map(function(i) { return i.url; }));
   strictEqual(calls, 2, 'selects after additional segments');
 });
 
@@ -1151,6 +1150,27 @@ test('clears the segment buffer on seek', function() {
   strictEqual(aborts, 1, 'cleared the segment buffer on a seek');
 });
 
+test('resets the switching algorithm if a request times out', function() {
+  player.src({
+    src: 'master.m3u8',
+    type: 'application/vnd.apple.mpegurl'
+  });
+  player.hls.mediaSource.trigger({
+    type: 'sourceopen'
+  });
+  standardXHRResponse(requests.shift()); // master
+  standardXHRResponse(requests.shift()); // media.m3u8
+  // simulate a segment timeout
+  requests[0].timedout = true;
+  requests.shift().abort();
+
+  standardXHRResponse(requests.shift());
+
+  strictEqual(player.hls.playlists.media(),
+              player.hls.playlists.master.playlists[1],
+              'reset to the lowest bitrate playlist');
+});
+
 test('disposes the playlist loader', function() {
   var disposes = 0, player, loaderDispose;
   player = createPlayer();