android TV-Building TV Channels，Developing a TV Input Service

》Building TV Channels

To provide your users a similar experience, use the TV Input Framework to create channels for publishing video or music content so that your media appears alongside traditional
TV channels in the programming guide.

Android supports receiving and playback of live video content through the TV Input Framework in Android 5.0 (API level 21). This framework provides a unified method for receiving
audio and video channel content from hardware sources, such as HDMI ports and built-in-tuners, and software sources, such as video streamed over the internet.The framework enables
developers to define live TV input sources by implementing a TV input service.

The TV Input Framework is designed to provide access to a wide variety of live TV input sources and bring them together in a single user interface for users to browse, view, and
enjoy content. Building a TV input service for your content can help make it more accessible on TV devices.

》Developing a TV Input Service

With the TV input service, you can provide parental controls, program guide information, and content ratings.

> To develop a TV input service, you implement the following components:

TvInputService

provides long-running and background
availability for the TV input

TvInputService.Session

maintains the TV
input state and communicates with the hosting app

TvContract

describes the channels and programs available
to the TV input

TvContract.Channels

represents information
about a TV channel

TvContract.Programs

describes a TV program
with data such as program title and start time

TvTrackInfo

represents an audio, video, or subtitle
track

TvContentRating

describes a content rating, allows
for custom content rating schemes

TvInputManager

provides an API to the system TV
app and manages the interaction with TV inputs and apps

>Your app manifest must declare your

TvInputService

.
Within that declaration, specify the

BIND_TV_INPUT

permission
to allow the service to connect the TV input to the system. A system service (

TvInputManagerService

) performs the binding and has that permission. The
system TV app sends requests to TV input services via the

TvInputManager

interface.
The service declaration must also include an intent filter that specifies the

TvInputService

as
the action to perform with the intent. Also within the service declaration, declare the service meta data in a separate XML resource.

<service android:name="com.example.sampletvinput.SampleTvInput"
android:label="@string/sample_tv_input_label"
android:permission="android.permission.BIND_TV_INPUT">
<intent-filter>
<action android:name="android.media.tv.TvInputService" />
</intent-filter>
<meta-data android:name="android.media.tv.input"
android:resource="@xml/sample_tv_input" />
</service>

<tv-input xmlns:android="http://schemas.android.com/apk/res/android"
android:setupActivity="com.example.sampletvinput.SampleTvInputSetupActivity" />

>the [code]onCreate()

method initializes the

CaptioningManager

and prepares to handle the

ACTION_BLOCKED_RATINGS_CHANGED

and

ACTION_PARENTAL_CONTROLS_ENABLED_CHANGED

actions. These actions describe system intents fired when the user changes the parental control settings, and when there is a change on the list of blocked ratings.[/code]

@Override
public void onCreate() {
super.onCreate();
mHandlerThread = new HandlerThread(getClass()
.getSimpleName());
mHandlerThread.start();
mDbHandler = new Handler(mHandlerThread.getLooper());
mHandler = new Handler();
mCaptioningManager = (CaptioningManager)
getSystemService(Context.CAPTIONING_SERVICE);

setTheme(android.R.style.Theme_Holo_Light_NoActionBar);

mSessions = new ArrayList<BaseTvInputSessionImpl>();
IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction(TvInputManager
.ACTION_BLOCKED_RATINGS_CHANGED);
intentFilter.addAction(TvInputManager
.ACTION_PARENTAL_CONTROLS_ENABLED_CHANGED);
registerReceiver(mBroadcastReceiver, intentFilter);
}

> The

TvInputService

creates
a

TvInputService.Session

that
implements

Handler.Callback

to
handle player state changes. With

onSetSurface()

,
the

TvInputService.Session

sets
the

Surface

with
the video content.

The

TvInputService.Session

handles
the

onTune()

event
when the user selects a channel, and notifies the system TV app for changes in the content and content meta data. These

notify()

methods are described
inControl Content and Handle
Track Selection further in this training.

The system TV app works with the setup activity you define for your TV input. The setup activity is required and must provide at least one channel record for the system database.
The system TV app will invoke the setup activity when it cannot find a channel for the TV input.