Merge "ExoPlayer developer guide" into klp-docs
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@ -373,6 +373,9 @@
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<li><a href="<?cs var:toroot ?>guide/topics/media/mediarouteprovider.html">
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<span class="en">Media Route Provider</span></a>
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</li>
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<li><a href="<?cs var:toroot ?>guide/topics/media/exoplayer.html">
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<span class="en">ExoPlayer</span></a>
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</li>
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<li><a href="<?cs var:toroot ?>guide/appendix/media-formats.html">
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<span class="en">Supported Media Formats</span></a>
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</li>
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514
docs/html/guide/topics/media/exoplayer.jd
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514
docs/html/guide/topics/media/exoplayer.jd
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page.title=ExoPlayer
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page.tags="audio","video","adaptive","streaming","DASH","smoothstreaming"
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@jd:body
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<div id="qv-wrapper">
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<div id="qv">
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<h2>In this document</h2>
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<ol>
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<li><a href="#overview">Overview</a></li>
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<li><a href="#trackrenderer">TrackRenderer</a></li>
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<li><a href="#samplesource">SampleSource</a>
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<ol>
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<li><a href="#mediaextractor">Providing media using MediaExtractor</a></li>
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<li><a href="#adaptive-playback">Providing media for adaptive playback</a>
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<ol>
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<li><a href="#format-selection">Format selection for adaptive playback</a></li>
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</ol>
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</li>
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</ol>
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<li><a href="#events">Player Events</a>
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<ol>
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<li><a href="#high-events">High level events</a></li>
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<li><a href="#low-events">Low level events</a></li>
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</ol>
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</li>
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<li><a href="#sending-messages">Sending messages to components</a></li>
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<li><a href="#customizing">Customizing ExoPlayer</a>
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<ol>
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<li><a href="#custom-guidelines">Custom component guidelines</a></li>
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</ol>
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</li>
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<li><a href="#drm">Digital Rights Management</a></li>
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</ol>
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<h2>Key Classes</h2>
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<ol>
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<li>{@link android.media.MediaCodec}</li>
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<li>{@link android.media.MediaExtractor}</li>
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<li>{@link android.media.AudioTrack}</li>
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</ol>
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<h2>Related Samples</h2>
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<ol>
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<li><a class="external-link" href="https://github.com/google/ExoPlayer">
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ExoPlayer Project</a></li>
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<li><a class="external-link" href="http://google.github.io/ExoPlayer/doc/reference/packages.html">
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Class Reference</a></li>
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</ol>
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</div>
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</div>
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<p>Playing videos and music is a popular activity on Android devices. The Android framework
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provides {@link android.media.MediaPlayer} as a quick solution for playing media with minimal
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code, and the {@link android.media.MediaCodec} and {@link android.media.MediaExtractor} classes
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are provided for building custom media players. The open source project, ExoPlayer, is a
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solution between these two options, providing a pre-built player that you can extend.</p>
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<p>ExoPlayer supports features not currently provided by
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{@link android.media.MediaPlayer}, including Dynamic adaptive streaming
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over HTTP (DASH), SmoothStreaming, and persistent caching. ExoPlayer can be extended
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to handle additional media formats, and because you include it as part of your app code,
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you can update it along with your app.</p>
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<p>This guide describes how to use ExoPlayer for playing Android supported media formats, as well as
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DASH and SmoothStreaming playback. This guide also discusses ExoPlayer events, messages, DRM
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support and guidelines for customizing the player.</p>
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<p class="note">
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<strong>Note:</strong> ExoPlayer is an open source project that is not part of the Android
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framework and is distributed separately from the Android SDK. The project contains a library and
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a demo app that shows both simple and more advanced use of ExoPlayer:</p>
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<ul>
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<li><a class="external-link" href="https://github.com/google/ExoPlayer/tree/master/library">
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ExoPlayer Library</a> — This part of the project contains the core library classes.</li>
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<li><a class="external-link" href="https://github.com/google/ExoPlayer/tree/master/demo/src/main/java/com/google/android/exoplayer/demo/simple">
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Simple Demo</a> — This part of the app demonstrates a basic use of ExoPlayer.</li>
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<li><a class="external-link" href="https://github.com/google/ExoPlayer/tree/master/demo/src/main/java/com/google/android/exoplayer/demo/full">
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Full Demo</a> — This part of the app demonstrates more advanced features,
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including the ability to select between multiple audio tracks, a background audio mode,
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event logging and DRM protected playback. </li>
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</ul>
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<h2 id="overview">Overview</h2>
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<p>ExoPlayer is a media player built on top of the {@link android.media.MediaExtractor} and
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{@link android.media.MediaCodec} APIs released in Android 4.1 (API level 16). At the core of this
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library is the {@code ExoPlayer} class. This class maintains the player’s global state, but makes few
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assumptions about the nature of the media being played, such as how the media data is obtained,
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how it is buffered or its format. You inject this functionality through ExoPlayer’s {@code
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prepare()} method in the form of {@code TrackRenderer} objects.</p>
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<p>ExoPlayer provides default {@code TrackRenderer} implementations for audio and
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video, which make use of the {@link android.media.MediaCodec} and {@link android.media.AudioTrack}
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classes in the Android framework. Both renderers require a {@code SampleSource} object, from which
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they obtain individual media samples for playback. Figure 1 shows the high level object model for
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an ExoPlayer implementation configured to play audio and video using these components.</p>
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<img src="{@docRoot}images/exoplayer/object-model.png" alt="" id="figure1" />
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<p class="img-caption">
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<strong>Figure 1.</strong> High level object model for an ExoPlayer configured to play audio
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and video using {@code TrackRenderer} objects
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</p>
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<h2 id="trackrenderer">TrackRenderer</h2>
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<p>A {@code TrackRenderer} processes a component of media for playback, such as
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video, audio or text. The ExoPlayer class invokes methods on its {@code TrackRenderer} instances from a
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single playback thread, and by doing so causes each media component to be rendered as the global
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playback position is advanced. The ExoPlayer library provides {@code MediaCodecVideoTrackRenderer} as
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the default implementations rendering video and {@code MediaCodecAudioTrackRenderer} for audio.
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Both implementations make use of {@link android.media.MediaCodec} to decode individual media
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samples. They can handle all audio and video formats supported by a given Android device
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(see <a href="http://developer.android.com/guide/appendix/media-formats.html">Supported Media
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Formats</a> for details). The ExoPlayer library also provides an implementation for rendering
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text called {@code TextTrackRenderer}.
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</p>
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<p>The code example below outlines the main steps required to instantiate an ExoPlayer to play video
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and audio using the standard {@code TrackRenderer} implementations.</p>
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<pre>
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// 1. Instantiate the player.
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player = ExoPlayer.Factory.newInstance(RENDERER_COUNT);
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// 2. Construct renderers.
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MediaCodecVideoTrackRenderer videoRenderer = …
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MediaCodecAudioTrackRenderer audioRenderer = ...
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// 3. Inject the renderers through prepare.
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player.prepare(videoRenderer, audioRenderer);
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// 4. Pass the surface to the video renderer.
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player.sendMessage(videoRenderer, MediaCodecVideoTrackRenderer.MSG_SET_SURFACE,
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surface);
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// 5. Start playback.
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player.setPlayWhenReady(true);
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...
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player.release(); // Don’t forget to release when done!
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</pre>
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<p>For a complete example, see the {@code SimplePlayerActivity} in the ExoPlayer demo app, which
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correctly manages an ExoPlayer instance with respect to both the {@link android.app.Activity} and
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{@link android.view.Surface} lifecycles.</p>
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<h2 id="samplesource">SampleSource</h2>
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<p>A standard {@code TrackRenderer} implementation requires a {@code SampleSource} to
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be provided in its constructor. A {@code SampleSource} object provides format information and
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media samples to be rendered. The ExoPlayer library provides {@code FrameworkSampleSource} and
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||||
{@code ChunkSampleSource}. The {@code FrameworkSampleSource} class uses {@link
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||||
android.media.MediaExtractor} to request, buffer and extract the media samples. The {@code
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||||
ChunkSampleSource} class provides adaptive playback using DASH or SmoothStreaming, and
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implements networking, buffering and media extraction within the ExoPlayer library.</p>
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<h3 id="mediaextractor">Providing media using MediaExtractor</h3>
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||||
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<p>
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In order to render media formats supported by the Android framework, the {@code
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FrameworkSampleSource} class uses {@link android.media.MediaExtractor} for networking,
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buffering and sample extraction functionality. By doing so, it supports any media container format
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supported by the version of Android where it is running. For more information about media formats
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||||
supported by Android, see <a href="{@docRoot}guide/appendix/media-formats.html">Supported
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||||
Media Formats</a>.
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||||
</p>
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<p>The diagram in Figure 2 shows the object model for an ExoPlayer implementation using
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{@code FrameworkSampleSource}.</p>
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<img src="{@docRoot}images/exoplayer/frameworksamplesource.png" alt="" id="figure2" />
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<p class="img-caption">
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<strong>Figure 2.</strong> Object model for an implementation of ExoPlayer that renders
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||||
media formats supported by Android using {@code FrameworkSampleSource}
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||||
</p>
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<p>The following code example outlines how the video and audio renderers are constructed to
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load the video from a specified URI.</p>
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<pre>
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FrameworkSampleSource sampleSource = new FrameworkSampleSource(
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activity, uri, null, 2);
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MediaCodecVideoTrackRenderer videoRenderer = new MediaCodecVideoTrackRenderer(
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sampleSource, null, true, MediaCodec.VIDEO_SCALING_MODE_SCALE_TO_FIT, 0,
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mainHandler, playerActivity, 50);
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MediaCodecAudioTrackRenderer audioRenderer = new MediaCodecAudioTrackRenderer(
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sampleSource, null, true);
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</pre>
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<p>The ExoPlayer demo app provides a complete implementation of this code in
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{@code DefaultRendererBuilder}. The {@code SimplePlaybackActivity} class uses it to play one
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of the videos available in the demo app. Note that in the example, video and audio
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are muxed, meaning they are streamed together from a single URI. The {@code FrameworkSampleSource}
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instance provides video samples to the {@code videoRenderer} object and audio samples to the
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{@code audioRenderer} object as they are extracted from the media container format. It is also
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possible to play demuxed media, where video and audio are streamed separately from different URIs.
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||||
This functionality can be achieved by having two {@code FrameworkSampleSource} instances instead
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of one.</p>
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||||
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||||
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<h3 id="adaptive-playback">Providing media for adaptive playback</h3>
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||||
<p>ExoPlayer supports adaptive streaming, which allows the quality of the
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media data to be adjusted during playback based on the network conditions. DASH
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and SmoothStreaming are examples of adaptive streaming technologies. Both these approaches
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||||
load media in small chunks (typically 2 to 10 seconds in duration). Whenever a chunk of media
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is requested, the client selects from a number of possible formats. For example, a client may
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select a high quality format if network conditions are good, or a low quality format if network
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||||
conditions are bad. In both techniques, video and audio are streamed separately.</p>
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<p>ExoPlayer supports adaptive playback through use of the {@code ChunkSampleSource} class,
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which loads chunks of media data from which individual samples can be extracted. Each {@code
|
||||
ChunkSampleSource} requires a {@code ChunkSource} object to be injected through its constructor,
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||||
which is responsible for providing media chunks from which to load and read samples. The {@code
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||||
DashMp4ChunkSource} and {@code SmoothStreamingChunkSource} classes provide DASH and SmoothStreaming
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playback using the FMP4 container format. The {@code DashWebMChunkSource} class uses the WebM
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container format to provide DASH playback.</p>
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||||
<p>All of the standard {@code ChunkSource} implementations require a {@code FormatEvaluator} and
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a {@code DataSource} to be injected through their constructors. The {@code FormatEvaluator}
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objects select from the available formats before each chunk is loaded. The {@code DataSource}
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||||
objects are responsible for actually loading the data. Finally, the {@code ChunkSampleSources}
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||||
require a {@code LoadControl} object that controls the chunk buffering policy.</p>
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<p>The object model of an ExoPlayer configured for a DASH adaptive playback is shown in the
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diagram below. This example uses an {@code HttpDataSource} object to stream the media over the
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network. The video quality is varied at runtime using the adaptive implementation of {@code
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FormatEvaluator}, while audio is played at a fixed quality level.</p>
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||||
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<img src="{@docRoot}images/exoplayer/adaptive-streaming.png" alt="" id="figure3" />
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<p class="img-caption">
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<strong>Figure 3.</strong> Object model for a DASH adaptive playback using ExoPlayer
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</p>
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||||
<p>The following code example outlines how the video and audio renderers are constructed.</p>
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||||
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||||
<pre>
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||||
Handler mainHandler = playerActivity.getMainHandler();
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LoadControl loadControl = new DefaultLoadControl(
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new BufferPool(BUFFER_SEGMENT_SIZE));
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BandwidthMeter bandwidthMeter = new BandwidthMeter();
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// Build the video renderer.
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DataSource videoDataSource = new HttpDataSource(userAgent,
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HttpDataSource.REJECT_PAYWALL_TYPES, bandwidthMeter);
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ChunkSource videoChunkSource = new DashMp4ChunkSource(videoDataSource,
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new AdaptiveEvaluator(bandwidthMeter), videoRepresentations);
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||||
ChunkSampleSource videoSampleSource = new ChunkSampleSource(videoChunkSource,
|
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loadControl, VIDEO_BUFFER_SEGMENTS * BUFFER_SEGMENT_SIZE, true);
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MediaCodecVideoTrackRenderer videoRenderer = new MediaCodecVideoTrackRenderer(
|
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videoSampleSource, null, true, MediaCodec.VIDEO_SCALING_MODE_SCALE_TO_FIT,
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0, mainHandler, playerActivity, 50);
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||||
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||||
// Build the audio renderer.
|
||||
DataSource audioDataSource = new HttpDataSource(userAgent,
|
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HttpDataSource.REJECT_PAYWALL_TYPES, bandwidthMeter);
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ChunkSource audioChunkSource = new DashMp4ChunkSource(audioDataSource,
|
||||
new FormatEvaluator.FixedEvaluator(), audioRepresentation);
|
||||
SampleSource audioSampleSource = new ChunkSampleSource(audioChunkSource,
|
||||
loadControl, AUDIO_BUFFER_SEGMENTS * BUFFER_SEGMENT_SIZE, true);
|
||||
MediaCodecAudioTrackRenderer audioRenderer = new MediaCodecAudioTrackRenderer(
|
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audioSampleSource, null, true);
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||||
</pre>
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|
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<p>In this code, {@code videoRepresentations} and {@code audioRepresentation} are {@code
|
||||
Representation} objects, each of which describes one of the available media streams. In the DASH
|
||||
model, these streams are parsed from a media presentation description (MPD) file. The ExoPlayer
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||||
library provides a {@code MediaPresentationDescriptionParser} class to obtain {@code
|
||||
Representation} objects from MPD files.</p>
|
||||
|
||||
<p class="note">
|
||||
<strong>Note:</strong> Building Representation objects from MPD files is not required. You can
|
||||
build Representation objects from other data sources if necessary.
|
||||
</p>
|
||||
|
||||
<p>The ExoPlayer demo app provides complete implementation of this code in
|
||||
{@code DashVodRendererBuilder}. The {@code SimplePlaybackActivity} class uses this builder to
|
||||
construct renderers for playing DASH sample videos in the demo app. It asynchronously fetches a
|
||||
specified MPD file in order to construct the required {@code Representation} objects. For an
|
||||
equivalent SmoothStreaming example, see the {@code SmoothStreamingRendererBuilder} class in the
|
||||
demo app.</p>
|
||||
|
||||
|
||||
<h4 id="format-selection">Format selection for adaptive playback</h4>
|
||||
|
||||
<p>For DASH and SmoothStreaming playback, consider both static format selection at the
|
||||
start of playback and dynamic format selection during playback. Static format selection should be
|
||||
used to filter out formats that should not be used throughout the playback, for example formats
|
||||
with resolutions higher than the maximum supported by the playback device. Dynamic selection varies
|
||||
the selected format during playback, typically to adapt video quality in response to changes in
|
||||
network conditions.</p>
|
||||
|
||||
<h5 id="static-selection">Static format selection</h5>
|
||||
|
||||
<p>When preparing a player, you should consider filtering out some of the available formats if
|
||||
they are not useable for playback. Static format selection allows you to filter out
|
||||
formats that cannot be used on a particular device or are not compatible with your player.
|
||||
For audio playback, this often means picking a single format to play and discarding the others.</p>
|
||||
|
||||
<p>For video playback, filtering formats can be more complicated. Apps should first
|
||||
eliminate any streams that whose resolution is too high to be played by the device. For H.264,
|
||||
which is normally used for DASH and SmoothStreaming playback, ExoPlayer’s {@code MediaCodecUtil}
|
||||
class provides a {@code maxH264DecodableFrameSize()} method that can be used to determine what
|
||||
resolution streams the device is able to handle, as shown in the following code example:</p>
|
||||
|
||||
<pre>
|
||||
int maxDecodableFrameSize = MediaCodecUtil.maxH264DecodableFrameSize();
|
||||
Format format = representation.format;
|
||||
if (format.width * format.height <= maxDecodableFrameSize) {
|
||||
// The device can play this stream.
|
||||
videoRepresentations.add(representation);
|
||||
} else {
|
||||
// The device isn't capable of playing this stream.
|
||||
}
|
||||
</pre>
|
||||
|
||||
<p>This approach is used to filter {@code Representations} in the {@code DashVodRendererBuilder}
|
||||
class of the ExoPlayer demo app, and similarly to filter track indices in {@code
|
||||
SmoothStreamingRendererBuilder}.</p>
|
||||
|
||||
<p>In addition to eliminating unsupported formats, it should be noted that the ability to
|
||||
seamlessly switch between H.264 streams of different resolution is an optional decoder feature
|
||||
available in Android 4.3 (API level 16) and higher, and so is not supported by all devices. The
|
||||
availability of an adaptive H.264 decoder can be queried using {@code MediaCodecUtil}, as shown in
|
||||
the following code example:</p>
|
||||
|
||||
<pre>
|
||||
boolean isAdaptive = MediaCodecUtil.getDecoderInfo(MimeTypes.VIDEO_H264).adaptive;
|
||||
</pre>
|
||||
|
||||
<p>The {@code MediaCodecVideoTrackRenderer} class is still able to handle resolution changes on
|
||||
devices that do not have adaptive decoders, however the switch is not seamless. Typically, the
|
||||
switch creates a small discontinuity in visual output lasting around 50-100ms. For devices that
|
||||
do not provide an adaptive decoder, app developers may choose to adapt between formats at
|
||||
a single fixed resolution so as to avoid discontinuities. The ExoPlayer demo app
|
||||
implementation does not pick a fixed resolution.</p>
|
||||
|
||||
|
||||
<h5 id="dynamic-selection">Dynamic format selection</h5>
|
||||
|
||||
<p>During playback, you can use a {@code FormatEvaluator} to dynamically select from the
|
||||
available video formats. The ExoPlayer library provides a {@code FormatEvaluator.Adaptive}
|
||||
implementation for dynamically selecting between video formats based on the current network
|
||||
conditions.</p>
|
||||
|
||||
<p>This class provides a simple, general purpose reference implementation, however you are
|
||||
encouraged to write your own {@code FormatEvaluator} implementation to best suit your particular
|
||||
needs.</p>
|
||||
|
||||
|
||||
<h2 id="events">Player Events</h2>
|
||||
|
||||
<p>During playback, your app can listen for events generated by the ExoPlayer that indicate the
|
||||
overall state of the player. These events are useful as triggers for updating the app user
|
||||
interface such as playback controls. Many ExoPlayer components also report their own component
|
||||
specific low level events, which can be useful for performance monitoring.</p>
|
||||
|
||||
|
||||
<h3 id="high-events">High level events</h3>
|
||||
|
||||
<p>ExoPlayer allows instances of {@code ExoPlayer.Listener} to be added and removed using its
|
||||
{@code addListener()} and {@code removeListener()} methods. Registered listeners are notified of
|
||||
changes in playback state, as well as when errors occur that cause playback to fail. For more
|
||||
information about the valid playback states and the possible transitions between them, see the
|
||||
ExoPlayer source code.</p>
|
||||
|
||||
<p>Developers who implement custom playback controls should register a listener and use it to
|
||||
update their controls as the player’s state changes. An app should also show an
|
||||
appropriate error to the user if playback fails.</p>
|
||||
|
||||
<h3 id="low-events">Low level events</h3>
|
||||
|
||||
<p>In addition to high level listeners, many of the individual components provided by the
|
||||
ExoPlayer library allow their own event listeners. For example, {@code
|
||||
MediaCodecVideoTrackRenderer} has constructors that take a {@code
|
||||
MediaCodecVideoTrackRenderer.EventListener}. In the ExoPlayer demo app, {@code SimplePlayerActivity}
|
||||
acts as a listener so that it can adjust the dimensions of the target surface to have the correct
|
||||
height and width ratio for the video being played:</p>
|
||||
|
||||
<pre>
|
||||
@Override
|
||||
public void onVideoSizeChanged(int width, int height) {
|
||||
surfaceView.setVideoWidthHeightRatio(height == 0 ? 1 : (float) width / height);
|
||||
}
|
||||
</pre>
|
||||
|
||||
<p>The {@code RendererBuilder} classes in the ExoPlayer demo app inject the activity as the
|
||||
listener, for example in the {@code DashVodRendererBuilder} class:</p>
|
||||
|
||||
<pre>
|
||||
MediaCodecVideoTrackRenderer videoRenderer = new MediaCodecVideoTrackRenderer(
|
||||
videoSampleSource, null, true, MediaCodec.VIDEO_SCALING_MODE_SCALE_TO_FIT,
|
||||
0, <strong>mainHandler, playerActivity</strong>, 50);
|
||||
</pre>
|
||||
|
||||
<p>Note that you must pass a {@link android.os.Handler} object to the renderer, which determines
|
||||
the thread on which the listener’s methods are invoked. In most cases, you should use a
|
||||
{@link android.os.Handler} associated with the app’s main thread, as is the case in this example.
|
||||
</p>
|
||||
|
||||
<p>Listening to individual components can be useful for adjusting UI based on player events, as
|
||||
in the example above. Listening to component events can also be helpful for logging performance
|
||||
metrics. For example, {@code MediaCodecVideoTrackRenderer} notifies its listener of dropped video
|
||||
frames. A developer may wish to log such metrics to track playback performance in their
|
||||
app.</p>
|
||||
|
||||
<p>Many components also notify their listeners when errors occur. Such errors may or may not
|
||||
cause playback to fail. If an error does not cause playback to fail, it may still result in
|
||||
degraded performance, and so you may wish to log all errors in order to track playback
|
||||
performance. Note that an ExoPlayer instance always notifies its high level listeners of errors that
|
||||
cause playback to fail, in addition to the listener of the individual component from which the error
|
||||
originated. Hence, you should display error messages to users only from high level listeners.
|
||||
Within individual component listeners, you should use error notifications only for informational
|
||||
purposes.</p>
|
||||
|
||||
|
||||
<h2 id="sending-messages">Sending messages to components</h2>
|
||||
|
||||
<p>Some ExoPlayer components allow changes in configuration during playback. By convention, you make
|
||||
these changes by passing asynchronous messages through the ExoPlayer to the component.
|
||||
This approach ensures both thread safety and that the configuration change is
|
||||
executed in order with any other operations being performed on the player.</p>
|
||||
|
||||
<p>The most common use of messaging is passing a target surface to
|
||||
{@code MediaCodecVideoTrackRenderer}:</p>
|
||||
|
||||
<pre>
|
||||
player.sendMessage(videoRenderer, MediaCodecVideoTrackRenderer.MSG_SET_SURFACE,
|
||||
surface);
|
||||
</pre>
|
||||
|
||||
<p>Note that if the surface needs to be cleared because
|
||||
{@link android.view.SurfaceHolder.Callback#surfaceDestroyed
|
||||
SurfaceHolder.Callback.surfaceDestroyed()} has been invoked, then you must send this
|
||||
message using the blocking variant of {@code sendMessage()}:</p>
|
||||
<p>
|
||||
|
||||
<pre>
|
||||
player.blockingSendMessage(videoRenderer,
|
||||
MediaCodecVideoTrackRenderer.MSG_SET_SURFACE, null);
|
||||
</pre>
|
||||
|
||||
<p>You must use a blocking message because the contract of {@link
|
||||
android.view.SurfaceHolder.Callback#surfaceDestroyed surfaceDestroyed()} requires that the
|
||||
app does not attempt to access the surface after the method returns. The {@code
|
||||
SimplePlayerActivity} class in the demo app demonstrates how the surface should be set and
|
||||
cleared.</p>
|
||||
|
||||
|
||||
<h2 id="customizing">Customizing ExoPlayer</h2>
|
||||
|
||||
<p>One of the main benefits of ExoPlayer over {@link android.media.MediaPlayer} is the ability to
|
||||
customize and extend the player to better suit the developer’s use case. The ExoPlayer library
|
||||
is designed specifically with this in mind, defining a number of abstract base classes and
|
||||
interfaces that make it possible for app developers to easily replace the default implementations
|
||||
provided by the library. Here are some use cases for building custom components:</p>
|
||||
|
||||
<ul>
|
||||
<li><strong>{@code TrackRenderer}</strong> - You may want to implement a custom
|
||||
{@code TrackRenderer} to handle media types other than audio and video. The {@code
|
||||
TextTrackRenderer} class within the ExoPlayer library is an example of how to implement a
|
||||
custom renderer. You could use the approach it demonstrates to render custom
|
||||
overlays or annotations. Implementing this kind of functionality as a {@code TrackRenderer}
|
||||
makes it easy to keep the overlays or annotations in sync with the other media being played.</li>
|
||||
<li><strong>{@code SampleSource}</strong> - If you need to support a container format not
|
||||
already handled by {@link android.media.MediaExtractor} or ExoPlayer, consider implementing a
|
||||
custom {@code SampleSource} class.</li>
|
||||
<li><strong>{@code FormatEvaluator}</strong> - The ExoPlayer library provides {@code
|
||||
FormatEvaluator.Adaptive} as a simple reference implementation that switches between different
|
||||
quality video formats based on the available bandwidth. App developers are encouraged to
|
||||
develop their own adaptive {@code FormatEvaluator} implementations, which can be designed to
|
||||
suit their use specific needs.</li>
|
||||
<li><strong>{@code DataSource}</strong> - ExoPlayer’s upstream package already contains a
|
||||
number of {@code DataSource} implementations for different use cases, such as writing and
|
||||
reading to and from a persistent media cache. You may want to implement you own
|
||||
{@code DataSource} class to load data in another way, such as a custom
|
||||
protocol or HTTP stack for data input.</li>
|
||||
</ul>
|
||||
|
||||
|
||||
<h3 id="custom-guidelines">Custom component guidelines</h3>
|
||||
|
||||
<p>If a custom component needs to report events back to the app, we recommend that you
|
||||
do so using the same model as existing ExoPlayer components, where an event listener is passed
|
||||
together with a {@link android.os.Handler} to the constructor of the component.</p>
|
||||
|
||||
<p>We recommended that custom components use the same model as existing ExoPlayer components to
|
||||
allow reconfiguration by the app during playback, as described in
|
||||
<a href="#sending-messages">Sending messages to components</a>.
|
||||
To do this, you should implement a {@code ExoPlayerComponent} and receive
|
||||
configuration changes in its {@code handleMessage()} method. Your app should pass
|
||||
configuration changes by calling ExoPlayer’s {@code sendMessage()} and {@code
|
||||
blockingSendMessage()} methods.</p>
|
||||
|
||||
|
||||
<h2 id="drm">Digital Rights Management</h2>
|
||||
|
||||
<p>On Android 4.3 (API level 18) and higher, ExoPlayer supports Digital Rights Managment (DRM)
|
||||
protected playback. In order to play DRM protected content with ExoPlayer, your app must
|
||||
inject a {@code DrmSessionManager} into the {@code MediaCodecVideoTrackRenderer} and {@code
|
||||
MediaCodecAudioTrackRenderer} constructors. A {@code DrmSessionManager} object is responsible for
|
||||
providing the {@code MediaCrypto} object required for decryption, as well as ensuring that the
|
||||
required decryption keys are available to the underlying DRM module being used.</p>
|
||||
|
||||
<p>The ExoPlayer library provides a default implementation of {@code DrmSessionManager}, called
|
||||
{@code StreamingDrmSessionManager}, which uses {@link android.media.MediaDrm}. The session
|
||||
manager supports any DRM scheme for which a modular DRM component exists on the device. All
|
||||
Android devices are required to support Widevine modular DRM (with L3 security, although many
|
||||
devices also support L1). Some devices may support additional schemes such as PlayReady.</p>
|
||||
|
||||
<p>The {@code StreamingDrmSessionManager} class requires a {@code MediaDrmCallback} to be
|
||||
injected into its constructor, which is responsible for actually making provisioning and key
|
||||
requests. You should implement this interface to make network requests to your license
|
||||
server and obtain the required keys. The {@code WidevineTestMediaDrmCallback} class in the
|
||||
ExoPlayer demo app sends requests to a Widevine test server.</p>
|
||||
BIN
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|
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Reference in New Issue
Block a user