drebabels drebabels - 5 months ago 28
Javascript Question

Problem retrieving HTML5 video duration

UPDATE: Ok so although I haven't solved this problem exactly, but I did figure out a work around that handles my biggest concern... the user experience.

First the video doesn't begin loading until after the viewer hits the play button, so I am assuming that the duration information wasn't available to be pulled (I don't know how to fix this particular issue... although I assume that it would involve just loading the video metadata separately from the video, but I don't even know if that is possible).

So to get around the fact that there is no duration data, I decided to hide the duration info (and actually the entire control) completely until you hit play.

I know... its cheating. But for now it makes me happy :)

That said... if anyone knows how to load the video metadata separately from the video file... please share. I think that should completely solve this problem.




I am working on building a HTML5 video player with a custom interface, but I am having some problems getting the video duration information to display.

My HTML is real simple (see below)

<video id="video" poster="image.jpg" controls>
<source src="video_path.mp4" type="video/mp4" />
<source src="video_path.ogv" type="video/ogg" />
</video>
<ul class="controls">
<li class="time"><p><span id="timer">0</span> of <span id="duration">0</span></p></li>
</ul>


And the javascript I am using to get and insert the duration is

var duration = $('#duration').get(0);
var vid_duration = Math.round(video.duration);
duration.firstChild.nodeValue = vid_duration;


The problem is nothing happens. I know the video file has the duration data because if I just use the default controls, it displays fine.

But the real strange thing is if I put alert(duration) in my code like so

alert(duration);
var vid_duration = Math.round(video.duration);
duration.firstChild.nodeValue = vid_duration;


then is works fine (minus the annoying alert that pops up). Any ideas what is happening here or how I can fix it?

Answer

The issue is in WebKit browsers; the video metadata is loaded after the video so is not available when the JS runs. You need to query the readyState attribute; this has a series of values from 0 to 4, letting you know what state the video is in; when the metadata has loaded you'll get a value of 1.

So you need to do something like:

window.setInterval(function(t){
  if (video.readyState > 0) {
    var duration = $('#duration').get(0);
    var vid_duration = Math.round(video.duration);
    duration.firstChild.nodeValue = vid_duration;
    clearInterval(t);
  }
},500);

I haven't tested that code, but it (or something like it) should work.

There's more information about media element attributes on developer.mozilla.org.