Chromecast will use ultrasonic sounds to connect your TV to your phone

The Google Chromecast apparently uses ultrasonic sounds to communicate with mobile devices that are not located on the local network. Revealed during a presentation by Chromecast Engineering Manager John Affaki at Google I/O yesterday, the streaming HDMI dongle will apparently play a unique ultrasonic sound via the television’s speakers in order to identify itself to an unknown device. The ultrasonic pulse will be picked up by the mobile device, in order to ensure the smartphone or tablet is in the immediate vicinity, reports GigaOM. Once support for nearby devices is enabled on the Chromecast itself, it will start transmitting the sound, which cannot be heard by humans, while a back-up PIN will also be available if the TV cannot transmit the sound or the host device cannot hear it.

Now this is cool: Google’s Chromecast team has found an interesting way to pair Chromecast streaming sticks with mobile devices that are not on the same Wi-Fi network. Pairing is done through inaudible, ultrasonic sounds, which should make sure that your neighbor won’t suddenly rickroll your TV screen. Google first announced support for off-network casting at its Google I/O 2014 developer conference in San Francisco Wednesday, and Chromecast Engineering Manager John Affaki said during a presentation at the conference Thursday that the goal was to make the social use of Chromecast in the living room easier. Google’s YouTube app already allows users to build collaborative queues for on-the-fly YouTube parties, and Affaki said Thursday that the support for these kinds of queues will be added to the Chromecast software developer’s kit to bring it to other apps as well. However, the challenge is that users need to be on the same Wi-Fi network, and sharing Wi-Fi passwords can be cumbersome. “The initial step of getting on the same Wi-Fi network can be really complicated,” said Affaki.