Using Audio Elements

This topic describes how your application can play audio content using the HTML5 "audio" element.

Related Info

The HTML5 audio element is a standard way to embed audio content in Web applications. You can use the audio element to stream audio files on a Samsung Smart TV. The audio element inherits all the properties and methods of the HTMLMediaElement interface.

Samsung TVs support a variety of standard audio formats. For more information on the supported formats, see the Media Specifications.

Implementing an Audio Player

To create an audio player using HTML5:

Create an audio element, and add attributes and properties.

You can create the element in HTML or in JavaScript:
- In HTML:
```
<body>
  <audio id='audio' src='yourAudioURI' loop controls> 
  </audio>
</body> 
```
  The following are some basic attributes for the HTML audio element. For more information, see the HTML <audio> element.
  - autoplay: Start playing the media as soon as it is ready.
  - controls: Show the playback controls.
  - loop: Start playing the media again from the beginning as soon as it ends.
  - muted: Mute the audio output.
  - preload: Specify whether the application can begin downloading the media or its meta data before the media is needed for playback.
  - src: Set the URI of the media file.
- In JavaScript:
```
var audioElement = document.createElement('audio'); 

audioElement.src = 'yourAudioURI'; 
audioElement.loop = true; 
audioElement.controls = true; 
audioElement.load();

document.body.appendChild(audioElement); 
```
  The following are some basic properties for the JavaScript audio element. You can also use the HTML attributes as properties. For more information, see the HTMLMediaElement Properties.
  - audioTracks: Lists the audio tracks contained in the element.
  - buffered: Returns the time ranges that the audio player has buffered.
  - currentTime: Indicates the current playback position, in seconds.
  - duration: Indicates the length of the media, in seconds.
  - ended: Indicates whether the media has finished playing.
  - paused: Indicates whether the media playback is paused.
  - volume: Indicates the audio volume, where 0.0 is silent and 1.0 is loudest.
Note :
The audio element only differs from the video element by having no visual component to the player. Attributes related to the visual component, such as height, width, and poster image, are not supported by the audio element.

Define event listeners.

For more information on the available events, see Media events.

var audioElement = document.getElementById('audio');

audioElement.addEventListener('loadeddata', function () {
  console.log('Audio loaded.');
});
audioElement.addEventListener('timeupdate', function () {
  console.log('Current time: ' + audioElement.currentTime);
});
audioElement.addEventListener('seeked', function () {
  console.log('Seek operation completed.');
});
audioElement.addEventListener('stalled', function () {
  console.log('Audio stalled.');
});
audioElement.addEventListener('ended', function () {
  console.log('Audio ended.');
});

Control the playback:
- Use the HTMLMediaElement Methods to control the audio player:
  - addTextTrack(): Add a text track to the audio player.
  - canPlayType(): Determine whether the specified media type can be played.
  - load(): Reset the audio player and restart media playback. This method can be useful for releasing resources after any src attribute and source element descendants have been removed.
  - pause(): Pause media playback. If playback is already paused, this method has no effect.
  - play(): Begin media playback.
- To move to a specific time in the media, set the currentTime property. The currentTime property sets or returns the current playback position, in seconds. When you set this property, the playback jumps to the specified position in the audio.
```
var audioElement = document.getElementById('audio');

/* Move 10 seconds forward */
var seekTime = audioElement.currentTime + 10;
if (seekTime >= 0 && seekTime <= audioElement.duration) {
  audioElement.currentTime = seekTime;
}

/* Move 10 seconds back */
var seekTime = audioElement.currentTime - 10;
if (seekTime >= 0 && seekTime <= audioElement.duration) {
  audioElement.currentTime = seekTime;
}

/* Move timeline to 30 seconds */
audioElement.currentTime = 30;
```
  Note :
  If the meta data of the media file is loaded, you can move to the specified time position even when the media file is not playing. For more information, see Retrieving Media Information.

To control the playback rate (trick play) of the media, set the playbackRate property as a multiplier for the playback rate.

Positive values for the playbackRate property play the media forwards, while negative values cause the media to play in reverse.
```
var audioElement = document.getElementById('audio');

/* Set to half speed */
var speed = 0.5;
audioElement.playbackRate = speed;

/* Set to double speed */
var speed = 2.0;
audioElement.playbackRate = speed;
```

Embedding Multiple Audio Files

To add multiple audio files to an audio player, for playing in sequence:

Create a source element for each audio file you want to add.
```
<audio id='audio'>
  <source class='active' src='yourAudioURI_1'></source>
  <source src='yourAudioURI_2'></source>
</audio>
```
Note :
To improve application performance, you can optionally add the type attribute to each source element. By indicating the MIME types of the media files using the type attribute, you can immediately skip media in formats that are not supported by the TV.

When the first audio file has finished playing, start playback for the next file:

var audioElement = document.getElementById('audio');

audioElement.addEventListener('ended', function(e){
  var activeSource = document.querySelector('#audio source.active');
  var nextSource = document.querySelector('#audio source.active + source') 
                  || document.querySelector('#audio source:first-child');

  // deactivate current source, and activate the next one
  activeSource.className = '';
  nextSource.className = 'active';

  // update the audio source and start playback
  audioElement.src = nextSource.src;
  audioElement.play();
})

Handling Errors

The error property returns an instance of the MediaError interface, which returns a numerical code value representing the error state of the media element.

Value	Name	Description
1	MEDIA_ERR_ABORTED	Fetching process aborted by the user
2	MEDIA_ERR_NETWORK	Network error occurred during downloading
3	MEDIA_ERR_DECODE	Error occurred during decoding
4	MEDIA_ERR_SRC_NOT_SUPPORTED	Media format not supported

Table 1. Media error states

var audioElement = document.getElementById('audio');

audioElement.addEventListener('error', function()
{
  /* Audio playback failed: show an error message */
  switch (audioElement.error.code)
  {
    case 1:
      // 'MEDIA_ERR_ABORTED : 1, Media data download is stopped by the user'
      break;
    case 2:
      // 'MEDIA_ERR_NETWORK : 2, Download is stopped due to network error'
      break;
    case 3:
      // 'MEDIA_ERR_DECODE : 3, Media data decoding failure'
      break;
    case 4:
      // 'MEDIA_ERR_SRC_NOT_SUPPORTED : 4, Format not supported'
      break
  }
}, false);