Use the IMA DAI SDK on Chromecast

Play VOD streams registered with Google Cloud Video Stitcher API

This guide demonstrates how to use the IMA DAI SDK for CAF Web Receivers to request and play a Google Cloud VOD stream session.

This guide expands on the basic example from full service DAI, adding support for streams registered with the Google Cloud Video Stitcher API.

Ensure your streaming format is supported by CAF web receivers before continuing.

For information on integrating with other platforms or on using the IMA client-side SDKs, see Interactive Media Ads SDKs.

Background

Before using this guide, familiarize yourself with the Chromecast Application Framework's Web Receiver protocol.

This guide assumes a basic level of familiarity with CAF receiver concepts, such as message interceptors, MediaInformation objects, and using the Cast Command and Control tool to emulate a CAF sender.

App components and architecture

Implementing VOD stream playback with the Google Cloud Video Stitcher API with the IMA CAF DAI SDK involves two main components as demonstrated in this guide:

• VideoStitcherVodStreamRequest: An object that defines a stream request to Google's servers.
• StreamManager: An object that handles communication between the video stream and the IMA DAI SDK, such as firing tracking pings and forwarding stream events to the publisher.

Set up a Google Cloud project

Enter the following variables for use in the IMA SDK:

• Location - The Google Cloud region where your VOD config was created.

  LOCATION

• Project Number: The Google Cloud project number using the Video Stitcher API.

  PROJECT_NUMBER

• OAuth Token: A service account's short lived OAuth Token with the Video Stitcher user role. Read more about creating short-lived credentials for service accounts.

  OAUTH_TOKEN

• Network Code: Google Ad Manager network code for requesting ads.

  NETWORK_CODE

  Ad tag URL - Ad Manager URL of the ad tag. For testing, you can use the IMA VMAP Pre-roll sample.

  AD_TAG_URI

• Content source URL - The URL string of the stream manifest for your VOD content.

  VOD_URI

Set up a custom cast receiver

To develop a custom cast receiver, you need the following:

• A Cast Developer Console account with test devices in an allowlist.

• A hosted web receiver app that is registered with your Cast Developer Console, and which can be modified to host the code provided by this guide.

• A sending app configured to use your web receiver app. For the purposes of this example, this guide uses the Cast Command and Control tool as the sender.

Prepare a sender to pass stream data to the receiver

First, configure your sender app to make a load request to your web receiver, containing the following fields in your platform's MediaInformation object.

Here are some code samples to help you get started:

// Create mediaInfo object
const mediaInfo = new chrome.cast.media.MediaInfo("CONTENT_ID");
mediaInfo.contentUrl = "BACKUP_STREAM_URL";
mediaInfo.contentType = "BACKUP_STREAM_MIMETYPE";
mediaInfo.streamType = chrome.cast.media.StreamType.VOD;
mediaInfo.customData = {
region: "LOCATION",
projectNumber: "PROJECT_NUMBER",
oAuthToken: "OAUTH_TOKEN",
networkCode: "NETWORK_CODE",
adTagUrl: "AD_TAG_URI"
contentSourceUrl: "VOD_URI"
};

// Make load request to cast web receiver
const castSession = cast.framework.CastContext.getInstance().getCurrentSession();
const request = new chrome.cast.media.LoadRequest(mediaInfo);
castSession.loadMedia(request).then(
  () => { console.log('Load succeed'); },
  (errorCode) => { console.log('Error code: ' + errorCode); });

JSONObject customData = new JSONObject()
  .put("region", "LOCATION")
  .put("projectNumber", "PROJECT_NUMBER")
  .put("oAuthToken", "OAUTH_TOKEN")
  .put("networkCode", "NETWORK_CODE")
  .put("adTagUrl", "AD_TAG_URI")
  .put("contentSourceUrl", "VOD_URI");

MediaInfo mediaInfo = MediaInfo.Builder("CONTENT_ID")
  .setContentUrl("BACKUP_STREAM_URL")
  .setContentType("BACKUP_STREAM_MIMETYPE")
  .setStreamType(MediaInfo.STREAM_TYPE_VOD)
  .setCustomData(customData)
  .build();

RemoteMediaClient remoteMediaClient = mCastSession.getRemoteMediaClient();
remoteMediaClient.load(new MediaLoadRequestData.Builder().setMediaInfo(mediaInfo).build());

NSURL url = [NSURL URLWithString:@"BACKUP_STREAM_URL"];
NSDictionary *customData = @{
  @"region": @"LOCATION",
  @"projectNumber": @"PROJECT_NUMBER",
  @"oAuthToken": @"OAUTH_TOKEN",
  @"networkCode": @"NETWORK_CODE",
  @"adTagUrl": @"AD_TAG_URI",
  @"contentSourceUrl": @"VOD_URI"
};

GCKMediaInformationBuilder *mediaInfoBuilder =
  [[GCKMediaInformationBuilder alloc] initWithContentID: @"CONTENT_ID"];
mediaInfoBuilder.contentURL = url;
mediaInfoBuilder.contentType = @"BACKUP_STREAM_MIMETYPE";
mediaInfoBuilder.streamType = GCKMediaStreamTypeNone;
mediaInfoBuilder.customData = customData;
self.mediaInformation = [mediaInfoBuilder build];

GCKRequest *request = [self.sessionManager.currentSession.remoteMediaClient loadMedia:self.mediaInformation];
if (request != nil) {
  request.delegate = self;
}

let url = URL.init(string: "BACKUP_STREAM_URL")
guard let mediaURL = url else {
  print("invalid mediaURL")
  return
}

let customData = [
  "region": "LOCATION",
  "projectNumber": "PROJECT_NUMBER",
  "oAuthToken": "OAUTH_TOKEN",
  "networkCode": "NETWORK_CODE",
  "adTagUrl": "AD_TAG_URI",
  "contentSourceUrl": "VOD_URI"
]

let mediaInfoBuilder = GCKMediaInformationBuilder.init(contentId: "CONTENT_ID")
mediaInfoBuilder.contentURL = mediaUrl
mediaInfoBuilder.contentType = "BACKUP_STREAM_MIMETYPE"
mediaInfoBuilder.streamType = GCKMediaStreamType.none
mediaInfoBuilder.customData = customData
mediaInformation = mediaInfoBuilder.build()

guard let mediaInfo = mediaInformation else {
  print("invalid mediaInformation")
  return
}

if let request = sessionManager.currentSession?.remoteMediaClient?.loadMedia(mediaInfo) {
  request.delegate = self
}

{
  "media": {
    "contentId": "CONTENT_ID",
    "contentUrl": "BACKUP_STREAM_URL",
    "contentType": "BACKUP_STREAM_MIMETYPE",
    "streamType": "VOD",
    "customData": {
      "region": "LOCATION",
      "projectNumber": "PROJECT_NUMBER",
      "oAuthToken": "OAUTH_TOKEN",
      "networkCode": "NETWORK_CODE",
      "adTagUrl": "AD_TAG_URI",
      "contentSourceUrl": "VOD_URI"
    }
  }
}

This custom load request can be sent to the receiver to test the rest of the steps.

Create a custom CAF web receiver

Create a custom web receiver, as seen in the CAF SDK Custom Web Receiver Guide.

Your receiver's code should look like the following:

<html>
<head>
  <script
      src="//www.gstatic.com/cast/sdk/libs/caf_receiver/v3/cast_receiver_framework.js">
  </script>
</head>
<body>
  <cast-media-player></cast-media-player>
  <script>
    const castContext = cast.framework.CastReceiverContext.getInstance()
    castContext.start();
  </script>
</body>
</html>

Import the IMA DAI SDK and get the Player Manager

Add a script tag to import the IMA DAI SDK for CAF to your web receiver, just after the script loading CAF. Then in the script tag that follows, store the receiver context and player manager as constants before starting the receiver.

<html>
<head>
  <script
      src="//www.gstatic.com/cast/sdk/libs/caf_receiver/v3/cast_receiver_framework.js"></script>
  <script src="//imasdk.googleapis.com/js/sdkloader/cast_dai.js"></script>
</head>
<body>
  <cast-media-player></cast-media-player>
  <script>
    const castContext = cast.framework.CastReceiverContext.getInstance();
    const playerManager = castContext.getPlayerManager();

    castContext.start();
  </script>
</body>
</html>

Initialize the IMA Stream Manager

Initialize the IMA Stream Manager.

<html>
<head>
  <script type="text/javascript"
      src="//www.gstatic.com/cast/sdk/libs/caf_receiver/v3/cast_receiver_framework.js"></script>
  <script src="//imasdk.googleapis.com/js/sdkloader/cast_dai.js"></script>
</head>
<body>
  <cast-media-player></cast-media-player>
  <script>
    const castContext = cast.framework.CastReceiverContext.getInstance();
    const playerManager = castContext.getPlayerManager();
    const streamManager = new google.ima.cast.dai.api.StreamManager();

    castContext.start();
  </script>
</body>
</html>

Create the Stream Manager Load Interceptor

Before your media items are passed to CAF, create your stream request in a LOAD message interceptor.

    const castContext = cast.framework.CastReceiverContext.getInstance();
    const playerManager = castContext.getPlayerManager();
    const streamManager = new google.ima.cast.dai.api.StreamManager();

    /**
     * Creates a VOD stream request object for the Video Stitcher API.
     * @param {!LoadRequestData} castRequest The request object from the cast sender
     * @return {StreamRequest} an IMA stream request
     */
    const createStreamRequest = (castRequest) => { /* ... */};

    /**
     * Initates a DAI stream request for the final stream manifest.
     * @param {!LoadRequestData} castRequest The request object from the cast sender
     * @return {Promise<LoadRequestData>} a promise that resolves to an updated castRequest, containing the DAI stream manifest
     */
    const createDAICastRequest = (castRequest) => {
        return streamManager.requestStream(castRequest, createStreamRequest(castRequest))
          .then((castRequestWithStreamData) => {
            console.log('Successfully made DAI stream request.');
            return castRequestWithStreamData;
          })
          .catch((error) => {
            console.log('Failed to make DAI stream request.');
            // CAF will automatically fallback to the content URL
            // that it can read from the castRequest object.
            return castRequest;
          });
    };

    playerManager.setMessageInterceptor(
        cast.framework.messages.MessageType.LOAD, createDAICastRequest);

    castContext.start();

Create the stream request

Complete the createStreamRequest function to create a Video Stitcher API VOD stream request, based on the CAF load request.

    /**
     * Creates a VOD stream request object for the Video Stitcher API.
     * @param {!LoadRequestData} castRequest The request object from the cast sender
     * @return {StreamRequest} an IMA stream request
     */
    const createStreamRequest = (castRequest) => {
      const streamRequest = new google.ima.cast.dai.api.VideoStitcherVodStreamRequest();
      const customData = castRequest.media.customData;

      streamRequest.region = customData.region;
      streamRequest.projectNumber = customData.projectNumber;
      streamRequest.oAuthToken = customData.oAuthToken;
      streamRequest.networkCode = customData.networkCode;
      streamRequest.adTagUrl = customData.adTagUrl;
      streamRequest.contentSourceUrl = customData.contentSourceUrl;

      return streamRequest;
    };