A system to keep cloud-based gamers in sync
Cloud gaming, which involves playing a video game remotely from the cloud, witnessed unprecedented growth during the lockdowns and gaming hardware shortages that occurred during the heart of the Covid-19 pandemic. Today, the burgeoning industry encompasses a $6 billion global market and more than 23 million players worldwide.
However, interdevice synchronization remains a persistent problem in cloud gaming and the broader field of networking. In cloud gaming, video, audio, and haptic feedback are streamed from one central source to multiple devices, such as a player’s screen and controller, which typically operate on separate networks. These networks aren’t synchronized, leading to a lag between these two separate streams. A player might see something happen on the screen and then hear it on their controller a half second later.
Inspired by this problem, scientists from MIT and Microsoft Research took a unique approach to synchronizing streams transmitted to two devices. Their system, called Ekho, adds inaudible white noise sequences to the game audio streamed from the cloud server. Then it listens for those sequences in the audio recorded by the player’s controller.
Ekho uses the mismatch between these noise sequences to continuously measure and compensate for the interstream delay.
In real cloud gaming sessions, the researchers showed that Ekho is highly reliable. The system can keep streams synchronized to within less than 10 milliseconds of each other, most of the time. Other synchronization methods resulted in consistent delays of more than 50 milliseconds.
And while Ekho was designed for cloud gaming, this technique could be used more broadly to synchronize media streams traveling to different devices, such as in training situations that utilize multiple augmented or virtual reality headsets.
“Sometimes, all it takes for a good solution to come out is to think outside what has been defined for you. The entire community has been fixed on how to solve this problem by synchronizing through the network. Synchronizing two streams by listening to the audio in the room sounded crazy, but it turned out to be a very good solution,” says Pouya Hamadanian, an electrical engineering and computer science (EECS) graduate student and lead author of a paper describing Ekho. More