Add documentation on seeking

pages/advanced/timing-apis.md

@@ -44,7 +44,49 @@ var time = player.time();
 
 ## Seeking
 
+dash.js provides two API endpoints to change the current playback position, namely `seek()`
+and `seekToPresentationTime()`. Both methods are available via the `MediaPlayer` class. As an example:
+
+````js
+var video = document.querySelector('video');
+var player = dashjs.MediaPlayer().create();
+player.initialize(video, url, false);
+player.seek(10)
+````
+
+While the `seek()` method expects values relative to `DVRWindow.start` the `seekToPresentationTime()` works with
+absolute presentation timestamps. Two examples to illustrate this behavior are depicted in the sections below.
+
 ### VoD
 
+For VoD playback both `seek()` and `seekToPresentationTime()` work in the same way and can be used interchangeable. This
+is due to the fact the DVR window for VoD spans over the whole duration of the content.
+
+![playback-time-vod]({{site.baseurl}}/assets/images/seek-api-vod.jpg)
+
 ### Live
 
+For live playback the `seek()` method expects values relative to the start of the DVR window.
+Internally `DVRWindow.start` is added to the provided value. The `seekToPresentationTime()` method uses absolute presentation timestamps.
+
+![playback-time-vod]({{site.baseurl}}/assets/images/seek-api-live.jpg)
+
+As an example, the following two code snippets each trigger a seek 20 seconds behind the live edge.
+
+##### seek()
+````js
+var video = document.querySelector('video');
+var player = dashjs.MediaPlayer().create();
+player.initialize(video, url, false);
+var duration = player.duration()
+player.seek(duration - 20);
+````
+
+##### seekToPresentationTime()
+````js
+var video = document.querySelector('video');
+var player = dashjs.MediaPlayer().create();
+player.initialize(video, url, false);
+var dvrWindowEnd = player.getDvrWindow().end
+player.seekToPresentationTime(dvrWindowEnd - 20);
+````