Skip to main content

How to jump to time offsets in HTML5 video

Let's say that you have a 30-minute WEBM video file, from which you just want to play the following video segments, jumping from one to the other automatically without interruptions:
  1. [00:01:25.00 - 00:02:25.00] -> from second 85 to 145
  2. [00:11:40.00 - 00:11:55.00] -> from second 700 to 715
  3. [00:20:26.00 - 00:21:07.00] -> from second 1226 to 1267
  4. [00:26:11.00 - 00:28:01.00] -> from second 1571 to 1681

To increase the complexity, let's think that you have these video segments in a PHP variable $arrayVideoSegments (normally the case if they were retrieved from the database).

  $arrayVideoSegments[0]->startTime = 85
  $arrayVideoSegments[0]->endTime = 145
  $arrayVideoSegments[1]->startTime = 700
  $arrayVideoSegments[1]->endTime = 715
  $arrayVideoSegments[2]->startTime = 1226
  $arrayVideoSegments[2]->endTime = 1267
  $arrayVideoSegments[3]->startTime = 1571
  $arrayVideoSegments[3]->endTime = 1681


The following code will play these video segments one after the other in an HTML5 Video object, using some Javascript and PHP.


<!-- BEGIN - HTML5 Video Object -->
<video id="myVideoPlayer" controls preload="metadata"">
  <source src="myVideo.webm" type="video/webm">
</video>
<!-- END - HTML5 Video Object -->


<!-- BEGIN - Migration from PHP Array to Javascript array -->
<script>
  <?php
    // Encode this array in a Javascript-friendly array
    $jsArrayVideoSegments = json_encode($arrayVideoSegments);
    // Declare this array in Javascript from PHP
    echo "var videoSegments = ". $jsArrayVideoSegments . ";\n";
  ?>
  playVideoSegments(videoSegments);
</script><!-- END - Migration from PHP Array to Javascript array -->

<!-- BEGIN - Video segment jump controller -->
<script language="javascript">
  function playVideoSegments(videoSegments) {
    var currentSegment = 0; // Segment being played
    var endTime = videoSegments[currentSegment]['endTime'];
    var videoPlayer = document.getElementById('myVideoPlayer');
    videoPlayer.currentTime = videoSegments[currentSegment]['startTime'];
    videoPlayer.play(); // Starts playing the video from startTime
    // This listener checks the video current time every 250ms    videoPlayer.addEventListener("timeupdate", function() {

      if(videoPlayer.currentTime >= endTime) {
        // Segment completed
        currentSegment++;
        if(currentSegment < videoSegments.length) { 
          // Not the last segment in the array
          videoPlayer.currentTime = videoSegments[currentSegment]['startTime'];
          endTime = videoSegments[currentSegment]['endTime'];
        } 
        else {
          // Last segment in the array is over
          videoPlayer.pause();
        }
      }
    }, false);
  }
</script>
<!-- END - Video segment jump controller -->

Popular posts from this blog

How to disable cookies on Google Analytics so that you don't need a consent banner

The integration of Google Analytics into a website or blog is not GDPR-compliant by default . You must first obtain explicit consent of the end-users to store cookies, describing in your privacy policy how you intend to use collected personal data. This is the reason why most websites nowadays display an annoying (but necessary) consent banner. If you fail to do so or if you only ask for implicit consent, you are at risk of being fined. However, it is possible to disable cookies on Google Analytics (GA) respecting end-users privacy, so that you don't need to ask for consent. The downside is that you will not be able to distinguish the type of user (unique vs new vs returning) and you will miss some session insights. If these details are not relevant for you, here is how you do it. Disable Google Analytics cookies on a custom website If you have a custom website with full access to the source code, you can simply insert the script below between the <head>  and </head>...
Read more

How to convert a PWA into an Android app in 5 minutes

In early 2021 I developed a memory game called Kobadoo  as a PWA (Progressive Web App) using ReactJS. It works pretty well as a browser game and gets decent traffic, but I wanted to reach more potential users by making it available on the official mobile app marketplaces. Since I didn't want to spend any time coding a native app, the easiest solution I found was to convert the PWA into a TWA (Trusted Web Activities) app. It barely takes 5 minutes to do it. TWA essentially allows you to easily create an Android app ( .apk file) that displays a full-screen browser view of your PWA. The user experience is almost identical to a web app and the views from the TWA will count as traffic on your web app. This means that if you have ads on your PWA, they will still work (and generate revenue) from the TWA. Another advantage is that every update you make on the PWA will be immediately reflected on the TWA without the need to submit a new version on Google Play. Here's how I convert...
Read more