# Bookmarks This guide shows how to implement bookmarking using the IMA SDK when using Dynamic Ad Insertion (DAI) for video-on-demand (VOD) streams. This assumes a working IMA DAI implementation, such as the one presented in [Get Started](/interactive-media-ads/docs/sdks/tvos/dai/quickstart). ## What is bookmarking? Bookmarking is the ability to save and then return to a specific point in the content stream. Suppose a user watches five minutes of content, leaves the video stream, and then returns to it. Bookmarking saves the user's position in the stream so the stream can pick up from where it left off, providing a seamless experience to the viewer. ## DAI bookmarking under the hood When bookmarking a DAI stream, you must record the stream id and time when the user leaves the video. When the user returns, re-request the stream and seek to the saved time. Since each instance of the requested stream can have ad breaks of different durations simply saving the stream time won't work. What you really want to do is continue from the same **content time**. ## Conversion methods to the rescue The IMA SDK provides a pair of methods to request the **content time** for a given **stream time** and the **stream time** for a given **content time**. Using these conversion methods you can store the bookmarked **content time** and then seek to the corresponding **stream time** in the new instance of the stream. Here's the approach, including a link to a sample app that shows a working bookmarking implementation.

Saving bookmarks

Save a bookmark when the Activity is paused.

- (void)viewWillAppear:(BOOL)animated {
  ...
  self.bookmarkTime =
      [self.streamManager contentTimeForStreamTime:CMTimeGetSeconds(
          self.playerViewController.player.currentTime)];
}

Loading bookmarks

Load the bookmark when re-requesting a stream. It's part of implementing the VideoStreamPlayer interface.

- (void)streamManagerIsPlaybackReady:(IMAStreamManager *)streamManager {
...
  if (self.bookmarkTime != 0) {
    NSTimeInterval streamTime = [self.streamManager
        streamTimeForContentTime:self.bookmarkTime];
    [self.playerViewController.player
        seekToTime:CMTimeMakeWithSeconds(streamTime, NSEC_PER_SEC)];
  }
}

Sample app

Sample app