Working with Channel Data

Your TV input must provide Electronic Program Guide (EPG) data for at least one channel in its setup activity. You should also periodically update that data, with consideration for the size of the update and the processing thread that handles it. This lesson discusses creating and updating channel and program data on the system database with these considerations in mind.

Get Permission

In order for your TV input to work with EPG data, it must declare the read and write permissions in its Android manifest file as follows:

<uses-permission android:name="com.android.providers.tv.permission.READ_EPG_DATA" />
<uses-permission android:name="com.android.providers.tv.permission.WRITE_EPG_DATA" />

Register Channels in the Database

The Android TV system database maintains records of channel data for TV inputs. In your setup activity, for each of your channels, you must map your channel data to the following fields of the TvContract.Channels class:

• COLUMN_DISPLAY_NAME - the displayed name of the channel
• COLUMN_DISPLAY_NUMBER - the displayed channel number
• COLUMN_INPUT_ID - the ID of the TV input service
• COLUMN_SERVICE_TYPE - the channel's service type
• COLUMN_TYPE - the channel's broadcast standard type
• COLUMN_VIDEO_FORMAT - the default video format for the channel

Although the TV input framework is generic enough to handle both traditional broadcast and over-the-top (OTT) content without any distinction, you may want to define the following columns in addition to those above to better identify traditional broadcast channels:

• COLUMN_ORIGINAL_NETWORK_ID - the television network ID
• COLUMN_SERVICE_ID - the service ID
• COLUMN_TRANSPORT_STREAM_ID - the transport stream ID

For internet streaming based TV inputs, assign your own values to the above accordingly so that each channel can be identified uniquely.

Pull your channel metadata (in XML, JSON, or whatever) from your backend server, and in your setup activity map the values to the system database as follows:

ContentValues values = new ContentValues();

values.put(Channels.COLUMN_DISPLAY_NUMBER, channel.mNumber);
values.put(Channels.COLUMN_DISPLAY_NAME, channel.mName);
values.put(Channels.COLUMN_ORIGINAL_NETWORK_ID, channel.mOriginalNetworkId);
values.put(Channels.COLUMN_TRANSPORT_STREAM_ID, channel.mTransportStreamId);
values.put(Channels.COLUMN_SERVICE_ID, channel.mServiceId);
values.put(Channels.COLUMN_VIDEO_FORMAT, channel.mVideoFormat);

Uri uri = context.getContentResolver().insert(TvContract.Channels.CONTENT_URI, values);

In the example above, channel is an object which holds channel metadata from the backend server.

Present Channel and Program Information

The system TV app presents channel and program information to users as they flip through channels, as shown in figure 1. To make sure the channel and program information works with the system TV app's channel and program information presenter, follow the guidelines below.

1. Channel number (COLUMN_DISPLAY_NUMBER)
2. Icon (android:icon in the TV input's manifest)
3. Program description (COLUMN_SHORT_DESCRIPTION)
4. Program title (COLUMN_TITLE)
5. Channel logo (TvContract.Channels.Logo)
   • Use the color #EEEEEE to match the surrounding text
   • Don't include padding
6. Poster art (COLUMN_POSTER_ART_URI)
   • Aspect ratio between 16:9 and 4:3

Figure 1. The system TV app channel and program information presenter.

The system TV app provides the same information through the program guide, including poster art, as shown in figure 2.

Figure 2. The system TV app program guide.

Update Channel Data

When updating existing channel data, use the update() method instead of deleting and re-adding the data. You can identify the current version of the data by using Channels.COLUMN_VERSION_NUMBER and Programs.COLUMN_VERSION_NUMBER when choosing the records to update.

Note: Adding channel data to the ContentProvider can take time. Only add current programs (those within two hours of the current time) when you update, and use a Sync Adapter to update the rest of the channel data in the background. See the Android TV Live TV Sample App for an example.

Batch Loading Channel Data

When updating the system database with a large amount of channel data, use the ContentResolver applyBatch() or bulkInsert() method. Here's an example using applyBatch():

ArrayList<ContentProviderOperation> ops = new ArrayList<>();
int programsCount = mChannelInfo.mPrograms.size();
for (int j = 0; j < programsCount; ++j) {
    ProgramInfo program = mChannelInfo.mPrograms.get(j);
    ops.add(ContentProviderOperation.newInsert(
            TvContract.Programs.CONTENT_URI)
            .withValues(programs.get(j))
            .withValue(Programs.COLUMN_START_TIME_UTC_MILLIS,
                    programStartSec * 1000)
            .withValue(Programs.COLUMN_END_TIME_UTC_MILLIS,
                    (programStartSec + program.mDurationSec) * 1000)
            .build());
    programStartSec = programStartSec + program.mDurationSec;
    if (j % 100 == 99 || j == programsCount - 1) {
        try {
            getContentResolver().applyBatch(TvContract.AUTHORITY, ops);
        } catch (RemoteException | OperationApplicationException e) {
            Log.e(TAG, "Failed to insert programs.", e);
            return;
        }
        ops.clear();
    }
}

Processing Channel Data Asynchronously

Data manipulation, such as fetching a stream from the server or accessing the database, should not block the UI thread. Using an AsyncTask is one way to perform updates asynchronously. For example, when loading channel info from a backend server, you can use AsyncTask as follows:

private static class LoadTvInputTask extends AsyncTask<Uri, Void, Void>> {

    private Context mContext;

    public LoadTvInputTask(Context context) {
        mContext = context;
    }

    @Override
    protected Void doInBackground(Uri... uris) {
        try {
            fetchUri(uris[0]);
        } catch (IOException e) {
          Log.d(“LoadTvInputTask”, “fetchUri error”);
        }
        return null;
    }

    private void fetchUri(Uri videoUri) throws IOException {
        InputStream inputStream = null;
        try {
            inputStream = mContext.getContentResolver().openInputStream(videoUri);
            XmlPullParser parser = Xml.newPullParser();
            try {
                parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, false);
                parser.setInput(inputStream, null);
                sTvInput = ChannelXMLParser.parseTvInput(parser);
                sSampleChannels = ChannelXMLParser.parseChannelXML(parser);
            } catch (XmlPullParserException e) {
                e.printStackTrace();
            }
        } finally {
            if (inputStream != null) {
                inputStream.close();
            }
        }
    }
}

If you need to update EPG data on a regular basis, consider using a Sync Adapter or JobScheduler to run the update process during idle time, such as every day at 3:00 a.m. See the Android TV live TV sample app for an example.

Other techniques to separate the data update tasks from the UI thread include using the HandlerThread class, or you may implement your own using Looper and Handler classes. See Processes and Threads for more information.