UC Davis – “If you’re thinking of buying a “smart” TV for the holidays, you ought to know that your new device is constantly capturing snapshots of what’s on screen and sending them back to the manufacturer — even if you are using the device as a computer monitor and not watching TV at all. The findings come from a recent study by computer scientists at the University of California, Davis; University College London; and Universidad Carlos III de Madrid, published in Proceedings of the 2024 ACM on Internet Measurement Conference. Smart TVs can do all the things “dumb” or linear televisions do, plus providing a wide range of internet services and additional channels offered by the manufacturers. You can also cast content from other devices, such as laptops and phones, either wirelessly or with an HDMI connection.  Tech companies collect information about our internet use and use it to sell targeted advertising. Zubair Shafiq, associate professor of computer science at UC Davis, and graduate student Yash Vekaria wanted to know how advertisers track you between devices. For example, you might be watching television in the living room, then go into another room to work on your laptop and see ads related to the shows you were just watching come up on your feeds. “To understand cross-device tracking, we wanted to first understand how these TV manufacturers or advertisers know what the user might be interested in. When we started looking into it, we came across technology referred to as ACR, which stands for automatic content recognition. And we found that that’s the main component which is responsible for generating audience segments on a smart TV,” Vekaria said. ACR can recognize content based on small snippets, similar to the Shazam app that can identify song and artist if you play it a piece of music. This ACR code is built into the operating system of smart TVs.  The researchers looked at TVs made by two leading manufacturers, Samsung and LG. Vekaria set up an intermediary server to capture traffic coming from a TV set in the lab and discover where it might be going on the internet. He also dug into the code running on the devices.  They found that the smart TVs captured snapshots of audio or video as often as every 10 milliseconds, batched them and used an algorithm to generate a “fingerprint” representing all the content over a time interval, such as the past minute. This fingerprint was sent to a company server and matched against a database of all the content available through the TV service.  “They do a match against the database to figure out what exact piece of content that user is streaming at this point in time. When they do this over a period of time, they can infer that, say, this person watches NFL from 9 to 12 p.m., but they generally watch news in the afternoon,” Vekaria said. The TV companies can then use this information to sell targeted advertising on their platform.  “These smart TV ad platforms have this vast profile of every single TV customer, and the ads on every TV get personalized based on that profile,” Shafiq said…”