<!DOCTYPE html>
<html>
<body>

<video id="myVideo" width="320" height="240" controls>
  <source src="movie.mp4" type="video/mp4">
  <source src="movie.ogg" type="video/ogg">
  Your browser does not support the video tag.
</video>

<p>Change the volume by either clicking the buttons or by adjusting the volume in the bottom right corner.</p>

<button onclick="setHalfVolume()" type="button">Set volume to 0.2</button>
<button onclick="setFullVolume()" type="button">Set volume to 1.0</button>

<p id="demo"></p>

<script>
// Get the video element with id="myVideo"
var x = document.getElementById("myVideo");

// Attach a "volumechange" event to the video
x.addEventListener("volumechange", getVolume);

// Display the current audio volume of the video in a p element with id="demo"
function getVolume() {
    document.getElementById("demo").innerHTML = "The audio volume is: " + x.volume;
}

// Set the audio volume to 0.2
function setHalfVolume() {
    x.volume = 0.2;
}

// Set the audio volume to 1.0 (the highest)
function setFullVolume() {
    x.volume = 1.0;
}
</script>

</body>
</html>