Detailed technical principles of Java libraries in Exoplayer frameworks details

Exoplayer is a powerful open source multimedia player framework, developed and maintained by Google.It is based on the Android platform and is written in Java language.Exoplayer's design goal is to provide a flexible and customized player framework that can meet various playback needs, such as local file playback, online streaming media playback, live broadcast, etc. The core of Exoplayer's technology is a set of Java libraries that play a key role in the framework.Below we will introduce the technical principles of these libraries in detail. 1. MediaSource: This library is responsible for obtaining data from different media sources and passing it to Exoplayer for playback.It supports common streaming protocols such as local files, HLS (HTTP LIVE Streaming), Dashic Adaptive Streaming Over Http.Using MediaSource, developers can easily handle different types of media sources and realize custom media logic. The following is an example code that uses MediaSource to load local files: // Create an Exoplayer example SimpleExoPlayer player = new SimpleExoPlayer.Builder(context).build(); // Create a local file MediaSource Uri uri = Uri.parse("file:///path/to/media/file"); MediaSource mediaSource = new ProgressiveMediaSource.Factory(new DefaultDataSourceFactory(context)) .createMediaSource(uri); // Bind the MediaSource to Exoplayer player.setMediaSource(mediaSource); // Prepare the player player.prepare(); // Start playing player.play(); 2. TrackSelector: This class library determines which media track should player choose to play.Media tracks can be video rails, audio orbiting, subtitle tracks, etc.TrackSelector uses the metadata information of the media files and combines the application of the application and the ability of the device for track selection.Developers can achieve specific track selection logic through custom tracingSelector, such as selecting the appropriate audio track according to the user's preference. The following is a sample code that uses the TrackSelector custom track selection logic: // Create an Exoplayer example SimpleExoPlayer player = new SimpleExoPlayer.Builder(context).build(); // Customly define a trackselector TrackSelector trackSelector = new DefaultTrackSelector(context) { @Override protected TrackSelection[] selectTracks(RendererCapabilities[] rendererCapabilities, TrackGroupArray[] rendererTrackGroupArrays, int[][][] rendererFormatSupports) throws ExoPlaybackException { // A custom logic of custom track selection here // For example, choose the appropriate audio track according to the user's preference // Return to the selected track result // ... } }; // Bind trackSelector to Exoplayer player.setTrackSelector(trackSelector); // ... 3. Renderer: This library is responsible for decoding and rendering media data.EXOPLAYER uses Renderer to handle different types of media tracks. For example, video rails use VideoRenderer, audio tracks use Audiorenderer, and so on.Renderer decodes media data into a format for rendering and provides it to the renderer for actual playback. Here are a sample code for custom renderr: // Customly define a renderer to handle custom media track class CustomRenderer extends Renderer { @Override public int supportsFormat(Format format) throws ExoPlaybackException { // Here is to determine whether the decoding supports according to the media format // Return to the format of renderer support // ... } @Override protected void onEnabled(boolean joining, boolean mayRenderStartOfStream) throws ExoPlaybackException { // Perform the initialization of renderer here // ... } @Override protected void onReleased() throws ExoPlaybackException { // Perform the renderer release operation here // ... } @Override protected void onStarted() throws ExoPlaybackException { // Here to process the starting logic of the renderer // ... } @Override protected void onStopped() throws ExoPlaybackException { // Here the stop logic of Renderer's stop playing // ... } // ... } // Configure the custom renderr through the Exoplayer configuration TrackSelector trackSelector = new DefaultTrackSelector(context); CustomRenderer customRenderer = new CustomRenderer(); RenderersFactory renderersFactory = (eventDispatcher, videoRendererEventListener, audioRendererEventListener, textRendererOutput, metadataRendererOutput) -> { // Return to the custom renderer array return new Renderer[] {customRenderer}; }; SimpleExoPlayer player = new SimpleExoPlayer.Builder(context, renderersFactory, trackSelector).build(); // ... These are the core libraries of the ExoPlayer framework, which jointly implemented multimedia playback and rendering functions.Through the flexible and customized characteristics provided by Exoplayer, developers can adapt to various media playback needs and provide an excellent playback experience.