Javascript Course

The code presented in this page shows how to get the duration (in seconds) of an audio /video file before upload it (AVI, MP3, MP4, MPEG, OGG), then, adds it into an input field in a form.


Script code

<h4>Example getting duration of audio/video file before upload</h4>
<p>Select an audio /video file</p>

<form action='#' method='post' enctype='multipart/form-data'>
 File: <input type='file' name='fup' id='fup' /><br>
 Duration: <input type='text' name='f_du' id='f_du' size='5' /> seconds<br>
 <input type='submit' value='Upload' />
</form>
<audio id='audio'></audio>

<script>
// Code to get duration of audio /video file before upload - from: https://coursesweb.net/

//register canplaythrough event to #audio element to can get duration
var f_duration =0; //store duration
document.getElementById('audio').addEventListener('canplaythrough', function(e){
 //add duration in the input field #f_du
 f_duration = Math.round(e.currentTarget.duration);
 document.getElementById('f_du').value = f_duration;
 URL.revokeObjectURL(obUrl);
});

//when select a file, create an ObjectURL with the file and add it in the #audio element
var obUrl;
document.getElementById('fup').addEventListener('change', function(e){
 var file = e.currentTarget.files[0];
 //check file extension for audio/video type
 if(file.name.match(/\.(avi|mp3|mp4|mpeg|ogg)$/i)){
 obUrl = URL.createObjectURL(file);
 document.getElementById('audio').setAttribute('src', obUrl);
 }
});
</script>
- The <audio> element is used to can get the duration of the file that is added in the "src" attribute.
- When a file is selected for upload, it is created an object of that file, and adds it in the #audio element.
- The JavaScript get the duration of the audio /video file from the <audio> element, stores it in the f_duration variable, and adds it in the input field.
- When the form is submited to upload the file, the duration (in seconds) it is send on server in the #f_du input field (in PHP: $_POST['f_du']).

- Demo (select an audio /video file):
File:
Duration: seconds

Daily Test with Code Example

HTML
CSS
JavaScript
PHP-MySQL
What attribute makes an option from <select> selected?
checked="checked" selected="selected" disabled="disabled"
<select name="a_name">
 <option value="val1">Option 1</option>
 <option value="val2" selected="selected">Option 2</option>
</select>
What CSS value allows to create color gradients for background?
contain repeat-x linear-gradient
#id {
  background: linear-gradient(top left, #1f1, #fff, #11f);
}
What statement creates an array in JavaScript?
[] {} new Object()
var arr = [1, "CoursesWeb.net", "MarPlo.net"];
alert(arr[2]);
Indicate the PHP function used to redirect to other page.
function() header() switch()
header("Location: http://coursesweb.net/");
exit;
Get Duration of Audio /Video file before Upload

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