Build the application class

Note: Before moving forward with this guide, you must complete the steps in Create the ads manager class.

In application.js, create the main class for your HbbTV app that interacts with the HbbTV broadcast. This class interacts with the broadcastAppManager and broadcastContainer. For an example of a similar class, see Handling the broadcast a/v object.

Modify this base HbbTV app to request an IMA stream and respond to ad break events.

Initialize the application

Initialize the application class in application.js, set up the broadcastAppManager, and broadcastContainer following the tutorial, Handling the broadcast a/v object. Afterwards, initiate new VideoPlayer and AdManager objects.

/** Main HbbTV Application. */
var HbbTVApp = function() {
  this.broadcastAppManager = document.getElementById('broadcast-app-manager');
  this.broadcastContainer = document.getElementById('broadcast-video');

  this.playState = -1; // -1 as null play state.

  try {
    this.applicationManager =
        this.broadcastAppManager.getOwnerApplication(document);
    this.applicationManager.show();
    this.broadcastContainer.bindToCurrentChannel();
    this.subscribedToStreamEvents = false;
    this.broadcastContainer.addEventListener(
        'PlayStateChange', this.onPlayStateChangeEvent.bind(this));

    debugView.log('HbbTVApp: App loaded');
    this.videoPlayer = new VideoPlayer();
    this.videoPlayer.setOnAdPodEnded(this.resumeBroadcast.bind(this));
  } catch (e) {
    debugView.log('HbbTVApp: No HbbTV device detected.');
    return;
  }

  this.adManager = new AdManager(this.videoPlayer);
};
application.js

Make an IMA stream request

In the HbbTVApp.onPlayStateChangeEvent() method, make a stream request in response to the app switching to the PRESENTING_PLAYSTATE. This approach prepares your app to load the ad pod manifest in response to an AD_BREAK_EVENT_ANNOUNCE event.

if (!this.subscribedToStreamEvents &&
    this.broadcastContainer.playState == PRESENTING_PLAYSTATE) {
  this.subscribedToStreamEvents = true;
  this.broadcastContainer.addStreamEventListener(
      STREAM_EVENT_URL, 'eventItem', function(event) {
        this.onStreamEvent(event);
      }.bind(this));
  debugView.log('HbbTVApp: Subscribing to stream events.');
  this.adManager.requestStream(NETWORK_CODE, CUSTOM_ASSET_KEY);
}
application.js

If your device doesn't correctly emit the broadcast container PlayStateChange event, use the setInterval() function to check for playstate changes:

setInterval(function() {
      if (!subscribedToStreamEvents &&
            this.broadcastContainer.playState == PRESENTING_PLAYSTATE) {
        subscribedToStreamEvents = true;
        this.broadcastContainer.addStreamEventListener(
            STREAM_EVENT_URL, 'eventItem', function(event) {
              this.onStreamEvent(event);
            }.bind(this));
        debugView.log('Subscribing to stream events');
        this.adManager.requestStream(NETWORK_CODE, CUSTOM_ASSET_KEY);
      }
      …

Listen to HbbTV stream events

Create the HbbTVApp.onStreamEvent() method to listen to the ad break events adBreakAnnounce, adBreakStart, and adBreakEnd:

/**
 * Callback for HbbTV stream event.
 * @param {!Event} event Stream event payload.
 */
HbbTVApp.prototype.onStreamEvent = function(event) {
  var eventData = JSON.parse(event.text);
  var eventType = eventData.type;
  if (eventType == AD_BREAK_EVENT_ANNOUNCE) {
    this.onAdBreakAnnounce(eventData);
  } else if (eventType == AD_BREAK_EVENT_START) {
    this.onAdBreakStart(eventData);
  } else if (eventType == AD_BREAK_EVENT_END) {
    this.onAdBreakEnd(eventData);
  }
};
application.js

Handle the HbbTV stream events

To handle the HbbTV stream events, complete the following steps:

1. To load the ad pod manifest in response to the adBreakAnnounce event, create the HbbTVApp.onAdBreakAnnounce() method:

   /**
    * Callback function on ad break announce stream event.
    * @param {!Event} event HbbTV stream event payload.
    */
   HbbTVApp.prototype.onAdBreakAnnounce = function(event) {
     var eventType = event.type;
     var eventDuration = event.duration;
     var eventOffset = event.offset;
     debugView.log(
         'HbbTV event: ' + eventType + ' duration: ' + eventDuration +
         's offset: ' + eventOffset + 's');
     this.adManager.loadAdPodManifest(NETWORK_CODE, CUSTOM_ASSET_KEY, eventDuration);
   };
   application.js

2. To switch to ad stream playback during ad breaks, create the HbbTVApp.onAdBreakStart() method:

   /**
    * Callback function on ad break start stream event.
    * @param {!Event} event HbbTV stream event payload.
    */
   HbbTVApp.prototype.onAdBreakStart = function(event) {
     debugView.log('HbbTV event: ' + event.type);
     if (!this.videoPlayer.isPreloaded()) {
       debugView.log('HbbTVApp: Switch aborted. ' +
                     'The ad preloading buffer is insufficient.');
       return;
     }
     this.stopBroadcast();
     this.videoPlayer.play();
   };
   application.js

3. To return to the content broadcast, create the HbbTVApp.onAdBreakEnd() method:

   /**
    * Callback function on ad break end stream event.
    * @param {!Event} event HbbTV stream event payload.
    */
   HbbTVApp.prototype.onAdBreakEnd = function(event) {
     debugView.log('HbbTV event: ' + event.type);
     this.videoPlayer.stop();
     this.resumeBroadcast();
   };
   application.js

You're now requesting and displaying IMA SDK ad pods in your HbbTV app. To compare your app with a completed sample app, see the IMA HbbTV sample on GitHub.