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.

1 files changed, 13 insertions, 496 deletions

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.title=ExoPlayer
 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> &mdash; 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> &mdash; 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> &mdash; The project homepage.</li>
+    <li><a class="external-link" href="http://google.github.io/ExoPlayer/guide.html">
+      Developer guide</a> &mdash; 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> &mdash; 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 &lt;= 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>
-&#64;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>