am 1ddb7cae: am eb09fe5e: Merge "Remove most of ExoPlayer page, replacing it with links to ExoPlayer site." into lmp-docs
* commit '1ddb7caedba247aa9174fc6c78c4ea6b3b4f5a89':
Remove most of ExoPlayer page, replacing it with links to ExoPlayer site.
diff --git a/docs/html/guide/topics/media/exoplayer.jd b/docs/html/guide/topics/media/exoplayer.jd
index 1e8601f..ad35523 100644
--- a/docs/html/guide/topics/media/exoplayer.jd
+++ b/docs/html/guide/topics/media/exoplayer.jd
@@ -2,511 +2,28 @@
page.tags="audio","video","adaptive","streaming","DASH","smoothstreaming"
@jd:body
-<div id="qv-wrapper">
- <div id="qv">
- <h2>In this document</h2>
- <ol>
- <li><a href="#overview">Overview</a></li>
- <li><a href="#trackrenderer">TrackRenderer</a></li>
- <li><a href="#samplesource">SampleSource</a>
- <ol>
- <li><a href="#mediaextractor">Providing media using MediaExtractor</a></li>
- <li><a href="#adaptive-playback">Providing media for adaptive playback</a>
- <ol>
- <li><a href="#format-selection">Format selection for adaptive playback</a></li>
- </ol>
- </li>
- </ol>
- <li><a href="#events">Player Events</a>
- <ol>
- <li><a href="#high-events">High level events</a></li>
- <li><a href="#low-events">Low level events</a></li>
- </ol>
- </li>
- <li><a href="#sending-messages">Sending messages to components</a></li>
- <li><a href="#customizing">Customizing ExoPlayer</a>
- <ol>
- <li><a href="#custom-guidelines">Custom component guidelines</a></li>
- </ol>
- </li>
- <li><a href="#drm">Digital Rights Management</a></li>
- </ol>
- <h2>Key Classes</h2>
- <ol>
- <li>{@link android.media.MediaCodec}</li>
- <li>{@link android.media.MediaExtractor}</li>
- <li>{@link android.media.AudioTrack}</li>
- </ol>
- <h2>Related Samples</h2>
- <ol>
- <li><a class="external-link" href="https://github.com/google/ExoPlayer">
- ExoPlayer Project</a></li>
- <li><a class="external-link" href="http://google.github.io/ExoPlayer/doc/reference/packages.html">
- Class Reference</a></li>
- </ol>
- </div>
-</div>
-
-
<p>Playing videos and music is a popular activity on Android devices. The Android framework
provides {@link android.media.MediaPlayer} as a quick solution for playing media with minimal
code, and the {@link android.media.MediaCodec} and {@link android.media.MediaExtractor} classes
are provided for building custom media players. The open source project, ExoPlayer, is a
solution between these two options, providing a pre-built player that you can extend.</p>
-<p>ExoPlayer supports features not currently provided by
- {@link android.media.MediaPlayer}, including Dynamic adaptive streaming
- over HTTP (DASH), SmoothStreaming, and persistent caching. ExoPlayer can be extended
- to handle additional media formats, and because you include it as part of your app code,
- you can update it along with your app.</p>
-
-<p>This guide describes how to use ExoPlayer for playing Android supported media formats, as well as
- DASH and SmoothStreaming playback. This guide also discusses ExoPlayer events, messages, DRM
- support and guidelines for customizing the player.</p>
+<p>ExoPlayer supports features not currently provided by {@link android.media.MediaPlayer},
+ including Dynamic adaptive streaming over HTTP (DASH), SmoothStreaming and Common Encryption. It's
+ designed to be easy to customize and extend, allowing many components to be replaced with custom
+ implementations. Because ExoPlayer is a library that you include in your application, it can be
+ easily updated along with your app.</p>
<p class="note">
<strong>Note:</strong> ExoPlayer is an open source project that is not part of the Android
- framework and is distributed separately from the Android SDK. The project contains a library and
- a demo app that shows both simple and more advanced use of ExoPlayer:</p>
+ framework and is distributed separately from the Android SDK. Visit the links below to find out
+ more.
<ul>
- <li><a class="external-link" href="https://github.com/google/ExoPlayer/tree/master/library">
- ExoPlayer Library</a> — This part of the project contains the core library classes.</li>
- <li><a class="external-link" href="https://github.com/google/ExoPlayer/tree/master/demo">
- Demo App</a> — This part of the project demonstrates usage of ExoPlayer,
- including the ability to select between multiple audio tracks, a background audio mode,
- event logging and DRM protected playback. </li>
+ <li><a class="external-link" href="http://google.github.io/ExoPlayer/">
+ ExoPlayer</a> — The project homepage.</li>
+ <li><a class="external-link" href="http://google.github.io/ExoPlayer/guide.html">
+ Developer guide</a> — Provides a wealth of information to help you get started.</li>
+ <li><a class="external-link" href="https://github.com/google/ExoPlayer">
+ GitHub project</a> — Contains the source code, as well as a demo app.</li>
</ul>
-
-
-<h2 id="overview">Overview</h2>
-
-<p>ExoPlayer is a media player built on top of the {@link android.media.MediaExtractor} and
- {@link android.media.MediaCodec} APIs released in Android 4.1 (API level 16). At the core of this
- library is the {@code ExoPlayer} class. This class maintains the player’s global state, but makes few
- assumptions about the nature of the media being played, such as how the media data is obtained,
- how it is buffered or its format. You inject this functionality through ExoPlayer’s {@code
- prepare()} method in the form of {@code TrackRenderer} objects.</p>
-
-<p>ExoPlayer provides default {@code TrackRenderer} implementations for audio and
- video, which make use of the {@link android.media.MediaCodec} and {@link android.media.AudioTrack}
- classes in the Android framework. Both renderers require a {@code SampleSource} object, from which
- they obtain individual media samples for playback. Figure 1 shows the high level object model for
- an ExoPlayer implementation configured to play audio and video using these components.</p>
-
-<img src="{@docRoot}images/exoplayer/object-model.png" alt="" id="figure1" />
-<p class="img-caption">
- <strong>Figure 1.</strong> High level object model for an ExoPlayer configured to play audio
- and video using {@code TrackRenderer} objects
-</p>
-
-
-<h2 id="trackrenderer">TrackRenderer</h2>
-
-<p>A {@code TrackRenderer} processes a component of media for playback, such as
- video, audio or text. The ExoPlayer class invokes methods on its {@code TrackRenderer} instances from a
- single playback thread, and by doing so causes each media component to be rendered as the global
- playback position is advanced. The ExoPlayer library provides {@code MediaCodecVideoTrackRenderer} as
- the default implementations rendering video and {@code MediaCodecAudioTrackRenderer} for audio.
- Both implementations make use of {@link android.media.MediaCodec} to decode individual media
- samples. They can handle all audio and video formats supported by a given Android device
- (see <a href="http://developer.android.com/guide/appendix/media-formats.html">Supported Media
- Formats</a> for details). The ExoPlayer library also provides an implementation for rendering
- text called {@code TextTrackRenderer}.
-</p>
-
-<p>The code example below outlines the main steps required to instantiate an ExoPlayer to play video
- and audio using the standard {@code TrackRenderer} implementations.</p>
-
-<pre>
-// 1. Instantiate the player.
-player = ExoPlayer.Factory.newInstance(RENDERER_COUNT);
-// 2. Construct renderers.
-MediaCodecVideoTrackRenderer videoRenderer = …
-MediaCodecAudioTrackRenderer audioRenderer = ...
-// 3. Inject the renderers through prepare.
-player.prepare(videoRenderer, audioRenderer);
-// 4. Pass the surface to the video renderer.
-player.sendMessage(videoRenderer, MediaCodecVideoTrackRenderer.MSG_SET_SURFACE,
- surface);
-// 5. Start playback.
-player.setPlayWhenReady(true);
-...
-player.release(); // Don’t forget to release when done!
-</pre>
-
-<p>For a complete example, see {@code PlayerActivity} and {@code DemoPlayer} in the ExoPlayer demo
- app. Between them these classes correctly manage an ExoPlayer instance with respect to both the
- {@link android.app.Activity} and {@link android.view.Surface} lifecycles.
-</p>
-
-
-<h2 id="samplesource">SampleSource</h2>
-
-<p>A standard {@code TrackRenderer} implementation requires a {@code SampleSource} to
- be provided in its constructor. A {@code SampleSource} object provides format information and
- media samples to be rendered. The ExoPlayer library provides {@code FrameworkSampleSource} and
- {@code ChunkSampleSource}. The {@code FrameworkSampleSource} class uses {@link
- android.media.MediaExtractor} to request, buffer and extract the media samples. The {@code
- ChunkSampleSource} class provides adaptive playback using DASH or SmoothStreaming, and
- implements networking, buffering and media extraction within the ExoPlayer library.</p>
-
-
-<h3 id="mediaextractor">Providing media using MediaExtractor</h3>
-
-<p>
- In order to render media formats supported by the Android framework, the {@code
- FrameworkSampleSource} class uses {@link android.media.MediaExtractor} for networking,
- buffering and sample extraction functionality. By doing so, it supports any media container format
- supported by the version of Android where it is running. For more information about media formats
- supported by Android, see <a href="{@docRoot}guide/appendix/media-formats.html">Supported
- Media Formats</a>.
-</p>
-
-<p>The diagram in Figure 2 shows the object model for an ExoPlayer implementation using
- {@code FrameworkSampleSource}.</p>
-
-<img src="{@docRoot}images/exoplayer/frameworksamplesource.png" alt="" id="figure2" />
-<p class="img-caption">
- <strong>Figure 2.</strong> Object model for an implementation of ExoPlayer that renders
- media formats supported by Android using {@code FrameworkSampleSource}
-</p>
-
-<p>The following code example outlines how the video and audio renderers are constructed to
- load the video from a specified URI.</p>
-
-<pre>
-FrameworkSampleSource sampleSource = new FrameworkSampleSource(
- activity, uri, null, 2);
-MediaCodecVideoTrackRenderer videoRenderer = new MediaCodecVideoTrackRenderer(
- sampleSource, null, true, MediaCodec.VIDEO_SCALING_MODE_SCALE_TO_FIT, 0,
- mainHandler, playerActivity, 50);
-MediaCodecAudioTrackRenderer audioRenderer = new MediaCodecAudioTrackRenderer(
- sampleSource, null, true);
-</pre>
-
-<p>The ExoPlayer demo app provides a complete implementation of this code in
- {@code DefaultRendererBuilder}. The {@code PlayerActivity} class uses it to play one
- of the videos available in the demo app. Note that in the example, video and audio
- are muxed, meaning they are streamed together from a single URI. The {@code FrameworkSampleSource}
- instance provides video samples to the {@code videoRenderer} object and audio samples to the
- {@code audioRenderer} object as they are extracted from the media container format. It is also
- possible to play demuxed media, where video and audio are streamed separately from different URIs.
- This functionality can be achieved by having two {@code FrameworkSampleSource} instances instead
- of one.</p>
-
-
-<h3 id="adaptive-playback">Providing media for adaptive playback</h3>
-
-<p>ExoPlayer supports adaptive streaming, which allows the quality of the
- media data to be adjusted during playback based on the network conditions. DASH
- and SmoothStreaming are examples of adaptive streaming technologies. Both these approaches
- load media in small chunks (typically 2 to 10 seconds in duration). Whenever a chunk of media
- is requested, the client selects from a number of possible formats. For example, a client may
- select a high quality format if network conditions are good, or a low quality format if network
- conditions are bad. In both techniques, video and audio are streamed separately.</p>
-
-<p>ExoPlayer supports adaptive playback through use of the {@code ChunkSampleSource} class,
- 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,
- which is responsible for providing media chunks from which to load and read samples. The {@code
- DashChunkSource} class provides DASH playback using the FMP4 and WebM container formats. The
- {@code SmoothStreamingChunkSource} class provides SmoothStreaming playback using the FMP4
- container format.</p>
-
-<p>All of the standard {@code ChunkSource} implementations require a {@code FormatEvaluator} and
- a {@code DataSource} to be injected through their constructors. The {@code FormatEvaluator}
- objects select from the available formats before each chunk is loaded. The {@code DataSource}
- objects are responsible for actually loading the data. Finally, the {@code ChunkSampleSources}
- require a {@code LoadControl} object that controls the chunk buffering policy.</p>
-
-<p>The object model of an ExoPlayer configured for a DASH adaptive playback is shown in the
- diagram below. This example uses an {@code HttpDataSource} object to stream the media over the
- network. The video quality is varied at runtime using the adaptive implementation of {@code
- FormatEvaluator}, while audio is played at a fixed quality level.</p>
-
-<img src="{@docRoot}images/exoplayer/adaptive-streaming.png" alt="" id="figure3" />
-<p class="img-caption">
- <strong>Figure 3.</strong> Object model for a DASH adaptive playback using ExoPlayer
-</p>
-
-<p>The following code example outlines how the video and audio renderers are constructed.</p>
-
-<pre>
-Handler mainHandler = playerActivity.getMainHandler();
-LoadControl loadControl = new DefaultLoadControl(
- new BufferPool(BUFFER_SEGMENT_SIZE));
-BandwidthMeter bandwidthMeter = new BandwidthMeter();
-
-// Build the video renderer.
-DataSource videoDataSource = new HttpDataSource(userAgent,
- HttpDataSource.REJECT_PAYWALL_TYPES, bandwidthMeter);
-ChunkSource videoChunkSource = new DashChunkSource(videoDataSource,
- new AdaptiveEvaluator(bandwidthMeter), videoRepresentations);
-ChunkSampleSource videoSampleSource = new ChunkSampleSource(videoChunkSource,
- loadControl, VIDEO_BUFFER_SEGMENTS * BUFFER_SEGMENT_SIZE, true);
-MediaCodecVideoTrackRenderer videoRenderer = new MediaCodecVideoTrackRenderer(
- videoSampleSource, null, true, MediaCodec.VIDEO_SCALING_MODE_SCALE_TO_FIT,
- 0, mainHandler, playerActivity, 50);
-
-// Build the audio renderer.
-DataSource audioDataSource = new HttpDataSource(userAgent,
- HttpDataSource.REJECT_PAYWALL_TYPES, bandwidthMeter);
-ChunkSource audioChunkSource = new DashChunkSource(audioDataSource,
- new FormatEvaluator.FixedEvaluator(), audioRepresentation);
-SampleSource audioSampleSource = new ChunkSampleSource(audioChunkSource,
- loadControl, AUDIO_BUFFER_SEGMENTS * BUFFER_SEGMENT_SIZE, true);
-MediaCodecAudioTrackRenderer audioRenderer = new MediaCodecAudioTrackRenderer(
- audioSampleSource, null, true);
-</pre>
-
-<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
- 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 DashRendererBuilder}. The {@code PlayerActivity} class uses this builder to
- construct renderers for playing DASH sample videos in the demo app. 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 DashRendererBuilder}
- 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 DemoPlayer}
- acts as the listener to multiple individual components, forwarding events to {@code PlayerActivity}.
- This approach allows {@code PlayerActivity} to 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, float pixelWidthAspectRatio) {
- surfaceView.setVideoWidthHeightRatio(
- height == 0 ? 1 : (width * pixelWidthAspectRatio) / height);
-}
-</pre>
-
-<p>The {@code RendererBuilder} classes in the ExoPlayer demo app inject the {@code DemoPlayer} as
- the listener to each component, for example in the {@code DashRendererBuilder} class:</p>
-
-<pre>
-MediaCodecVideoTrackRenderer videoRenderer = new MediaCodecVideoTrackRenderer(
- sampleSource, null, true, MediaCodec.VIDEO_SCALING_MODE_SCALE_TO_FIT, 5000,
- null, <strong>player.getMainHandler(), player</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.</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>
