Media sources

In ExoPlayer, every piece of media is represented by a MediaItem. However internally, the player needs MediaSource instances to play the content. The player creates these from media items using a MediaSource.Factory.

By default the player uses a DefaultMediaSourceFactory, which can create instances of the following content MediaSource implementations:

DefaultMediaSourceFactory can also create more complex media sources depending on the properties of the corresponding media items. This is described in more detail on the Media items page.

For apps that need media source setups that are not supported by the default configuration of the player, there are several options for customization.

Customizing media source creation

When building the player, a MediaSource.Factory can be injected. For example, if an app wants to insert ads and use a CacheDataSource.Factory to support caching, an instance of DefaultMediaSourceFactory can be configured to match these requirements and injected during player construction:


  val mediaSourceFactory: MediaSource.Factory =
      .setLocalAdInsertionComponents(adsLoaderProvider, playerView)
  val player = ExoPlayer.Builder(context).setMediaSourceFactory(mediaSourceFactory).build()


MediaSource.Factory mediaSourceFactory =
    new DefaultMediaSourceFactory(context)
        .setLocalAdInsertionComponents(adsLoaderProvider, /* adViewProvider= */ playerView);
ExoPlayer player =
    new ExoPlayer.Builder(context).setMediaSourceFactory(mediaSourceFactory).build();

The DefaultMediaSourceFactory JavaDoc describes the available options in more detail.

It's also possible to inject a custom MediaSource.Factory implementation, for example to support creation of a custom media source type. The factory's createMediaSource(MediaItem) will be called to create a media source for each media item that is added to the playlist.

Media source based playlist API

The ExoPlayer interface defines additional playlist methods that accept media sources rather than media items. This makes it possible to bypass the player's internal MediaSource.Factory and pass media source instances to the player directly:


// Set a list of media sources as initial playlist.
// Add a single media source.

// Can be combined with the media item API.
exoPlayer.addMediaItem(/* index= */ 3, MediaItem.fromUri(videoUri))



// Set a list of media sources as initial playlist.
// Add a single media source.

// Can be combined with the media item API.
exoPlayer.addMediaItem(/* index= */ 3, MediaItem.fromUri(videoUri));


Advanced media source composition

ExoPlayer provides multiple MediaSource implementations to modify and compose other MediaSource instances. These are most useful in cases where multiple customizations have to be combined and none of the simpler setup paths are sufficient.

  • ClippingMediaSource: Allows to clip media to a specified timestamp range. If this is the only modification, it's preferable to use MediaItem.ClippingConfiguration instead.
  • FilteringMediaSource: Filters available tracks to the specified types, for example, just exposing the video track from a file that contains both audio and video. If this is the only modification, it's preferable to use track selection parameters instead.
  • MergingMediaSource: Merges multiple media sources to play in parallel. In almost all cases, it's advisable to call the constructor with adjustPeriodTimeOffsets and clipDurations set to true to ensure all sources start and end at the same time. If this modification is done to add side-loaded subtitles, it's preferable to use MediaItem.SubtitleConfiguration instead.
  • ConcatenatingMediaSource2: Merges multiple media source to play consecutively. The user-visible media structure exposes a single Timeline.Window, meaning that it looks like a single item. If this modification is done to play multiple items that are not supposed to look like a single one, it's preferable to use the playlist API methods like Player.addMediaItem instead.
  • SilenceMediaSource: Generates silence for a specified duration that is useful to fill gaps.
  • AdsMediaSource: Extends a media source with client-side ad insertion capabilities. Refer to the ad insertion guide for details.
  • ServerSideAdInsertionMediaSource: Extends a media source with server-side ad insertion capabilities. Refer to the ad insertion guide for details.