@dmlap quicker quality switches when bandwidth changes. Closes #285.

@@ -10,6 +10,7 @@ CHANGELOG
 * @mikrohard: Trim whitespace in playlist. ([view](https://github.com/videojs/videojs-contrib-hls/pull/282))
 * @mikrohard: Trim whitespace in playlist. ([view](https://github.com/videojs/videojs-contrib-hls/pull/282))
 * @dmlap add a contrib option to merge PRs without squashing ([view](https://github.com/videojs/videojs-contrib-hls/pull/287))
 * @dmlap add a contrib option to merge PRs without squashing ([view](https://github.com/videojs/videojs-contrib-hls/pull/287))
 * @mikrohard allow playback of TS files with NITs. Don't warn about PCR PIDs. ([view](https://github.com/videojs/videojs-contrib-hls/pull/284))
 * @mikrohard allow playback of TS files with NITs. Don't warn about PCR PIDs. ([view](https://github.com/videojs/videojs-contrib-hls/pull/284))
+* @dmlap quicker quality switches when bandwidth changes. ([view](https://github.com/videojs/videojs-contrib-hls/pull/285))
 
 
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@@ -315,6 +315,12 @@ videojs.Hls.prototype.setCurrentTime = function(currentTime) {
     return 0;
     return 0;
   }
   }
 
 
+  // it's clearly an edge-case but don't thrown an error if asked to
+  // seek within an empty playlist
+  if (!this.playlists.media().segments) {
+    return 0;
+  }
+
   // save the seek target so currentTime can report it correctly
   // save the seek target so currentTime can report it correctly
   // while the seek is pending
   // while the seek is pending
   this.lastSeekedTime_ = currentTime;
   this.lastSeekedTime_ = currentTime;
@@ -578,6 +584,11 @@ videojs.Hls.prototype.fillBuffer = function(offset) {
     return;
     return;
   }
   }
 
 
+  // if a playlist switch is in progress, wait for it to finish
+  if (this.playlists.state === 'SWITCHING_MEDIA') {
+    return;
+  }
+
   // if the video has finished downloading, stop trying to buffer
   // if the video has finished downloading, stop trying to buffer
   segment = this.playlists.media().segments[this.mediaIndex];
   segment = this.playlists.media().segments[this.mediaIndex];
   if (!segment) {
   if (!segment) {

@@ -976,6 +976,35 @@ test('only appends one segment at a time', function() {
   equal(appends, 0, 'did not append while updating');
   equal(appends, 0, 'did not append while updating');
 });
 });
 
 
+test('waits to download new segments until the media playlist is stable', function() {
+  var media;
+  player.src({
+    src: 'manifest/master.m3u8',
+    type: 'application/vnd.apple.mpegurl'
+  });
+  openMediaSource(player);
+  standardXHRResponse(requests.shift()); // master
+  player.hls.bandwidth = 1; // make sure we stay on the lowest variant
+  standardXHRResponse(requests.shift()); // media
+
+  // mock a playlist switch
+  media = player.hls.playlists.media();
+  player.hls.playlists.media = function() {
+    return media;
+  };
+  player.hls.playlists.state = 'SWITCHING_MEDIA';
+
+  standardXHRResponse(requests.shift()); // segment 0
+
+  equal(requests.length, 0, 'no requests outstanding');
+  player.hls.checkBuffer_();
+  equal(requests.length, 0, 'delays segment fetching');
+
+  player.hls.playlists.state = 'LOADED_METADATA';
+  player.hls.checkBuffer_();
+  equal(requests.length, 1, 'resumes segment fetching');
+});
+
 test('cancels outstanding XHRs when seeking', function() {
 test('cancels outstanding XHRs when seeking', function() {
   player.src({
   player.src({
     src: 'manifest/media.m3u8',
     src: 'manifest/media.m3u8',
@@ -1321,6 +1350,19 @@ test('segment 500 should trigger MEDIA_ERR_ABORTED', function () {
   equal(4, player.hls.error.code, 'Player error code should be set to MediaError.MEDIA_ERR_ABORTED');
   equal(4, player.hls.error.code, 'Player error code should be set to MediaError.MEDIA_ERR_ABORTED');
 });
 });
 
 
+test('seeking in an empty playlist is a non-erroring noop', function() {
+  player.src({
+    src: 'manifest/empty-live.m3u8',
+    type: 'application/vnd.apple.mpegurl'
+  });
+  openMediaSource(player);
+
+  requests.shift().respond(200, null, '#EXTM3U\n');
+
+  player.currentTime(183);
+  equal(player.currentTime(), 0, 'remains at time zero');
+});
+
 test('duration is Infinity for live playlists', function() {
 test('duration is Infinity for live playlists', function() {
   player.src({
   player.src({
     src: 'http://example.com/manifest/missingEndlist.m3u8',
     src: 'http://example.com/manifest/missingEndlist.m3u8',