android_frameworks_base/docs/html/guide/topics/media/mediarouteprovider.jd

page.title=Media Route Provider
page.tags="mediarouteprovider","mediacontrolintent"
@jd:body

<div id="qv-wrapper">
  <div id="qv">
    <h2>In this document</h2>
    <ol>
      <li><a href="#overview">Overview</a>
        <ol>
          <li><a href="#dist">Distribution of route providers</a></li>
          <li><a href="#playback-types">Types of playback</a></li>
          <li><a href="#mr-packages">Media router packages</a></li>
        </ol>
      </li>
      <li><a href="#provider-service">Creating a Provider Service</a></li>
      <li><a href="#route-caps">Specifying Route Capabilities</a>
        <ol>
          <li><a href="#route-cat">Route categories</a></li>
          <li><a href="#media-types">Media types and protocols</a></li>
          <li><a href="#playback-ctrls">Playback controls</a></li>
          <li><a href="#mrpd">MediaRouteProviderDescriptor</a></li>
        </ol>
      </li>
      <li><a href="#ctrl-routes">Controlling Routes</a></li>
    </ol>
    <h2>Key Classes</h2>
    <ol>
      <li>{@link android.support.v7.media.MediaRouteProvider}</li>
      <li>{@link android.support.v7.media.MediaRouteProviderDescriptor}</li>
      <li>{@link android.support.v7.media.MediaRouteProvider.RouteController RouteController}</li>
    </ol>
    <h2>Related Samples</h2>
    <ol>
      <li><a href="{@docRoot}samples/MediaRouter/index.html">MediaRouter</a></li>
    </ol>
  </div>
</div>

<p>Users want to play media content from their Android devices bigger, brighter, and louder on
  connected playback devices such as televisions, stereos,
  and home theater equipment. As a manufacturer of these devices, allowing Android users to
  instantly show a picture, play a song, or share a video for friends and family using your product
  can make it much more compelling and engaging.</p>

<p>The Android media router framework allows manufacturers to enable playback on their devices
  through a standardized interface called a {@link android.support.v7.media.MediaRouteProvider}.
  A route provider defines a common interface for playing media on a receiver device, making it
  possible to play media on your equipment from any Android application that supports media
  routes.</p>

<p>This guide discusses how to create a media route provider for a receiver device and make it
  available to other media playback applications that run on Android.</p>

<h2 id="overview">Overview</h2>

<p>The Android media router framework enables media app developers and media playback device
  manufacturers to connect through a common API and common user interface. App developers that
  implement a {@link android.support.v7.media.MediaRouter} interface can then connect to the
  framework and play content to devices that participate in the media router framework. Media
  playback device manufacturers can participate in the framework by publishing a {@link
  android.support.v7.media.MediaRouteProvider} that allows other applications to connect to and
  play media on the receiver devices. Figure 1 illustrates how an app connects to a receiving
  device through the media router framework.</p>

<img src="{@docRoot}images/mediarouter/media-route-provider-framework.png" alt="" id="figure1"/>
<p class="img-caption">
  <strong>Figure 1.</strong> Overview of how media route provider classes provide communication
  from a media app to a receiver device.
</p>

<p>When you build a media route provider for your receiver device, the provider serves the
following purposes:</p>

<ul>
  <li>Describe and publish the capabilities of the receiver device so other apps can discover it
    and use its playback features.</li>
  <li>Wrap the programming interface of the receiver device and its communication
    transport mechanisms to make the device compatible with the media router framework.</li>
</ul>


<h3 id="dist">Distribution of route providers</h3>

<p>A media route provider is distributed as part of an Android app. Your route provider can be
  made available to other apps by extending
  {@link android.support.v7.media.MediaRouteProviderService} or wrapping your implementation of
  {@link android.support.v7.media.MediaRouteProvider} with your own service and declaring an intent
  filter for the media route provider. These steps allow other apps to discover and make use of
  your media route.</p>

<p>
  <strong>Note:</strong> The app containing the media route provider can also include a
  <a href="{@docRoot}guide/topics/media/mediarouter.html">MediaRouter</a> interface to the
  route provider, but this is not required.
</p>


<h3 id="playback-types">Types of playback</h3>

<p>There are two main types of playback supported by the media router framework. A media route
  provider can support one or both types of playback, depending on the capabilities of your playback
  equipment and the functionality you want to support:</p>

<ul>
  <li><strong>Remote Playback</strong> — This approach uses the receiver device to handle the
    content data retrieval, decoding, and playback, while an Android device in the user's hand is
    used as a remote control. This approach is used by Android apps that support
    <a href="https://developers.google.com/cast/">Google Cast</a>.</li>
  <li><strong>Secondary Output</strong> — With this approach, the Android media application
    retrieves, renders and streams video or music directly to the receiver device. This approach is
    used to support Wireless Display output on Android.</li>
</ul>


<h3 id="mr-packages">Media router packages</h3>

<p>
  The media router APIs are provided as part of the Android Support Library version 18 and higher,
  in the <a href="{@docRoot}tools/support-library/features.html#v7-mediarouter">v7-mediarouter</a>
  support library. You should use the classes in the
  {@link android.support.v7.media} package for media route provider functions.
  These APIs are compatible with devices running Android 2.1 (API level 7) and higher.
</p>

<p class="caution">
  <strong>Caution:</strong> There is another set of media router APIs provided in the
  {@link android.media} class package that have been superseded by the
  <a href="{@docRoot}tools/support-library/features.html#v7-mediarouter">v7-mediarouter</a>
  support library. You <em>should not</em> use the {@link android.media} classes for
  implementing media route provider functions.
</p>

<p>In order to use the {@link android.support.v7.media} media router classes, you
  must add the <a href="{@docRoot}tools/support-library/features.html#v7-mediarouter"
  >v7-mediarouter support library package</a> to your app development project. For more
  information on adding support libraries to your app development project, see
  <a href="{@docRoot}tools/support-library/setup.html">Support Library Setup</a>.
</p>


<h2 id="provider-service">Creating a Provider Service</h2>

<p>The media router framework must be able to discover and connect to your media route provider
  to allow other applications to use your route. In order to do this, the media router framework
  looks for apps that declare a media route provider intent action. When another app wants to
  connect to your provider, the framework must be able to invoke and connect to it, so your provider
  must be encapsulated in a {@link android.app.Service}.</p>

<p>The following example code shows the declaration of a media route provider service and the
  intent filter in a manifest, which allows it to be discovered and used by the media router
  framework:</p>

<pre>
&lt;service android:name=".provider.SampleMediaRouteProviderService"
    android:label="&#64;string/sample_media_route_provider_service"
    android:process=":mrp"&gt;
    &lt;intent-filter&gt;
        &lt;action android:name="android.media.MediaRouteProviderService" /&gt;
    &lt;/intent-filter&gt;
&lt;/service&gt;
</pre>

<p>This manifest example declares a service that wraps the actual media route provider classes.
  The Android media router framework provides the
  {@link android.support.v7.media.MediaRouteProviderService} class for use as a service wrapper for
  media route providers. The following example code demonstrates how to use this wrapper
  class:</p>

<pre>
public class SampleMediaRouteProviderService extends MediaRouteProviderService {

    &#64;Override
    public MediaRouteProvider onCreateMediaRouteProvider() {
        return new SampleMediaRouteProvider(this);
    }
}
</pre>


<h2 id="route-caps">Specifying Route Capabilities</h2>

<p>Apps connecting to the media router framework can discover your media route through your
  app's manifest declarations, but they also need to know the capabilities of the media routes you
  are providing. Media routes can be of different types and have different features, and other apps
  need to be able to discover these details to determine if they are compatible with your route.</p>

<p>The media router framework allows you to define and publish the capabilities of your media
  route through {@link android.content.IntentFilter} objects, {@link
  android.support.v7.media.MediaRouteDescriptor} objects and a {@link
  android.support.v7.media.MediaRouteProviderDescriptor}. This section explains how to use these
  classes to publish the details of your media route for other apps.</p>


<h3 id="route-cat">Route categories</h3>

<p>As part of the programmatic description of your media route provider, you must specify
  whether your provider supports remote playback, secondary output, or both. These are the route
  categories provided by the media router framework:</p>

<ul>
  <li>{@link android.support.v7.media.MediaControlIntent#CATEGORY_LIVE_AUDIO CATEGORY_LIVE_AUDIO}
    &mdash; Output of audio to a secondary output device, such as a wireless-enabled music system.
    </li>
  <li>{@link android.support.v7.media.MediaControlIntent#CATEGORY_LIVE_VIDEO CATEGORY_LIVE_VIDEO}
    &mdash; Output of video to a secondary output device, such as Wireless Display devices.</li>
  <li>{@link android.support.v7.media.MediaControlIntent#CATEGORY_REMOTE_PLAYBACK
    CATEGORY_REMOTE_PLAYBACK} &mdash; Play video or audio on a separate device which handles media
    retrieval, decoding, and playback, such as
    <a href="https://www.google.com/url?q=http://www.google.com/chromecast">Chromecast</a> devices.
    </li>
</ul>

<p>In order to include these settings in a description of your media route, you insert them into
  an {@link android.content.IntentFilter} object, which you later add to a
  {@link android.support.v7.media.MediaRouteDescriptor} object:</p>

<pre>
public final class SampleMediaRouteProvider extends MediaRouteProvider {
    private static final ArrayList&lt;IntentFilter&gt; CONTROL_FILTERS_BASIC;
    static {
        IntentFilter videoPlayback = new IntentFilter();
        <strong>videoPlayback.addCategory(MediaControlIntent.CATEGORY_REMOTE_PLAYBACK);</strong>
        CONTROL_FILTERS_BASIC = new ArrayList&lt;IntentFilter&gt;();
        CONTROL_FILTERS_BASIC.add(videoPlayback);
    }
}

</pre>

<p>If you specify the {@link android.support.v7.media.MediaControlIntent#CATEGORY_REMOTE_PLAYBACK
  CATEGORY_REMOTE_PLAYBACK} intent, you must also define what media types and
  playback controls are supported by your media route provider. The next section describes how to
  specify these settings for your device.</p>


<h3 id="media-types">Media types and protocols</h3>

<p>A media route provider for a remote playback device must specify the media types and transfer
  protocols it supports. You specify these settings using the {@link android.content.IntentFilter}
  class and the {@link android.content.IntentFilter#addDataScheme addDataScheme()} and
  {@link android.content.IntentFilter#addDataType addDataType()} methods of that object. The
  following code snippet demonstrates how to define an intent filter for supporting remote video
  playback using http, https, and Real Time Streaming Protocol (RTSP):</p>

<pre>
public final class SampleMediaRouteProvider extends MediaRouteProvider {

    private static final ArrayList&lt;IntentFilter&gt; CONTROL_FILTERS_BASIC;

    static {
        IntentFilter videoPlayback = new IntentFilter();
        videoPlayback.addCategory(MediaControlIntent.CATEGORY_REMOTE_PLAYBACK);
        videoPlayback.addAction(MediaControlIntent.ACTION_PLAY);
        videoPlayback.addDataScheme("http");
        videoPlayback.addDataScheme("https");
        videoPlayback.addDataScheme("rtsp");
        addDataTypeUnchecked(videoPlayback, "video/*");
        CONTROL_FILTERS_BASIC = new ArrayList&lt;IntentFilter&gt;();
        CONTROL_FILTERS_BASIC.add(videoPlayback);
    }
    ...

    private static void addDataTypeUnchecked(IntentFilter filter, String type) {
        try {
            filter.addDataType(type);
        } catch (MalformedMimeTypeException ex) {
            throw new RuntimeException(ex);
        }
    }
}

</pre>


<h3 id="playback-ctrls">Playback controls</h3>

<p>A media route provider that offers remote playback must specify the types of media controls
  it supports. These are the general types of control that media routes can provide:</p>

<ul>
  <li><strong>Playback controls</strong>, such as play, pause, rewind, and fast-forward.</li>
  <li><strong>Queuing features</strong>, which allow the sending app to add and remove items
    from a playlist which is maintained by the receiver device.</li>
  <li><strong>Session features</strong>, which prevent sending apps from interfering with each
    other by having the receiver device provide a session id to the requesting app and then checking
    that id with each subsequent playback control request.</li>
</ul>

<p>The following code example demonstrates how to construct an intent filter for supporting
  basic media route playback controls:</p>

<pre>
public final class SampleMediaRouteProvider extends MediaRouteProvider {
    private static final ArrayList&lt;IntentFilter&gt; CONTROL_FILTERS_BASIC;
    static {
        ...
        IntentFilter playControls = new IntentFilter();
        playControls.addCategory(MediaControlIntent.CATEGORY_REMOTE_PLAYBACK);
        playControls.addAction(MediaControlIntent.ACTION_SEEK);
        playControls.addAction(MediaControlIntent.ACTION_GET_STATUS);
        playControls.addAction(MediaControlIntent.ACTION_PAUSE);
        playControls.addAction(MediaControlIntent.ACTION_RESUME);
        playControls.addAction(MediaControlIntent.ACTION_STOP);
        CONTROL_FILTERS_BASIC = new ArrayList&lt;IntentFilter&gt;();
        CONTROL_FILTERS_BASIC.add(videoPlayback);
        CONTROL_FILTERS_BASIC.add(playControls);
    }
    ...
}
</pre>

<p>For more information about the available playback control intents, see the
  {@link android.support.v7.media.MediaControlIntent} class.</p>


<h3 id="mrpd">MediaRouteProviderDescriptor</h3>

<p>After defining the capabilities of your media route using {@link
  android.content.IntentFilter} objects, you can then create a descriptor object for publishing to
  the Android media router framework. This descriptor object contains the specifics of your media
  route's capabilities so that other applications can determine how to interact with your media
  route.</p>

<p>The following example code demonstrates how to add the previously created intent filters to a
  {@link android.support.v7.media.MediaRouteProviderDescriptor} and set the descriptor for use by
  the media router framework:</p>

<pre>
public SampleMediaRouteProvider(Context context) {
    super(context);
    publishRoutes();
}

private void publishRoutes() {
    Resources r = getContext().getResources();
    // Create a route descriptor using previously created IntentFilters
    MediaRouteDescriptor routeDescriptor = new MediaRouteDescriptor.Builder(
            VARIABLE_VOLUME_BASIC_ROUTE_ID,
            r.getString(R.string.variable_volume_basic_route_name))
            .setDescription(r.getString(R.string.sample_route_description))
            .addControlFilters(CONTROL_FILTERS_BASIC)
            .setPlaybackStream(AudioManager.STREAM_MUSIC)
            .setPlaybackType(MediaRouter.RouteInfo.PLAYBACK_TYPE_REMOTE)
            .setVolumeHandling(MediaRouter.RouteInfo.PLAYBACK_VOLUME_VARIABLE)
            .setVolumeMax(VOLUME_MAX)
            .setVolume(mVolume)
            .build();
    // Add the route descriptor to the provider descriptor
    MediaRouteProviderDescriptor providerDescriptor =
            new MediaRouteProviderDescriptor.Builder()
            .addRoute(routeDescriptor)
            .build();

    // Publish the descriptor to the framework
    setDescriptor(providerDescriptor);
}
</pre>

<p>For more information on the available descriptor settings, see the reference documentation
  for {@link android.support.v7.media.MediaRouteDescriptor} and {@link
  android.support.v7.media.MediaRouteProviderDescriptor}.</p>


<h2 id="ctrl-routes">Controlling Routes</h2>

<p>When an application connects to your media route provider, the provider receives playback
  commands through the media router framework sent to your route by other apps. To handle these
  requests, you must provide an implementation of a {@link
  android.support.v7.media.MediaRouteProvider.RouteController} class, which processes the commands
  and handles the actual communication to your receiver device.</p>

<p>The media router framework calls the {@link
  android.support.v7.media.MediaRouteProvider#onCreateRouteController onCreateRouteController()}
  method of your route provider to obtain an instance of this class and then routes requests to it.
  These are the key methods of the {@link
  android.support.v7.media.MediaRouteProvider.RouteController} class, which you must implement for
  your media route provider:</p>

<ul>
  <li>{@link android.support.v7.media.MediaRouteProvider.RouteController#onSelect onSelect()}
    &mdash; Called when an application selects your route for playback. You use this method to do
    any preparation work that may be required before media playback begins.</li>
  <li>{@link android.support.v7.media.MediaRouteProvider.RouteController#onControlRequest
    onControlRequest()} &mdash; Sends specific playback commands to the receiving device.</li>
  <li>{@link android.support.v7.media.MediaRouteProvider.RouteController#onSetVolume
    onSetVolume()} &mdash; Sends a request to the receiving device to set the playback volume to a
    specific value.</li>
  <li>{@link android.support.v7.media.MediaRouteProvider.RouteController#onUpdateVolume
    onUpdateVolume()} &mdash; Sends a request to the receiving device to modify the playback
    volume by a specified amount.</li>
  <li>{@link android.support.v7.media.MediaRouteProvider.RouteController#onUnselect
    onUnselect()} &mdash; Called when an application unselects a route.</li>
  <li>{@link android.support.v7.media.MediaRouteProvider.RouteController#onRelease onRelease()}
    &mdash; Called when the route is no longer needed by the framework, allowing it to free its
    resources.</li>
</ul>

<p>All playback control requests, except for volume changes, are directed to the {@link
  android.support.v7.media.MediaRouteProvider.RouteController#onControlRequest onControlRequest()}
  method. Your implementation of this method must parse the control requests and respond to them
  appropriately. Here is an example implementation of this method which processes commands for a
  remote playback media route:</p>

<pre>
private final class SampleRouteController extends
        MediaRouteProvider.RouteController {
    ...

    &#64;Override
    public boolean onControlRequest(Intent intent, ControlRequestCallback callback) {

        String action = intent.getAction();

        if (intent.hasCategory(MediaControlIntent.CATEGORY_REMOTE_PLAYBACK)) {
            boolean success = false;
            if (action.equals(MediaControlIntent.ACTION_PLAY)) {
                success = handlePlay(intent, callback);
            } else if (action.equals(MediaControlIntent.ACTION_ENQUEUE)) {
                success = handleEnqueue(intent, callback);
            } else if (action.equals(MediaControlIntent.ACTION_REMOVE)) {
                success = handleRemove(intent, callback);
            } else if (action.equals(MediaControlIntent.ACTION_SEEK)) {
                success = handleSeek(intent, callback);
            } else if (action.equals(MediaControlIntent.ACTION_GET_STATUS)) {
                success = handleGetStatus(intent, callback);
            } else if (action.equals(MediaControlIntent.ACTION_PAUSE)) {
                success = handlePause(intent, callback);
            } else if (action.equals(MediaControlIntent.ACTION_RESUME)) {
                success = handleResume(intent, callback);
            } else if (action.equals(MediaControlIntent.ACTION_STOP)) {
                success = handleStop(intent, callback);
            } else if (action.equals(MediaControlIntent.ACTION_START_SESSION)) {
                success = handleStartSession(intent, callback);
            } else if (action.equals(MediaControlIntent.ACTION_GET_SESSION_STATUS)) {
                success = handleGetSessionStatus(intent, callback);
            } else if (action.equals(MediaControlIntent.ACTION_END_SESSION)) {
                success = handleEndSession(intent, callback);
            }

            Log.d(TAG, mSessionManager.toString());
            return success;
        }
        return false;
    }
    ...
}
</pre>

<p>It is important to understand that the {@link
  android.support.v7.media.MediaRouteProvider.RouteController} class is intended to act as a wrapper
  for the API to your media playback equipment. The implementation of the methods in this class is
  entirely dependent on the programmatic interface provided by your receiving device.</p>