Smart TV tracking opt-outs may not work on Samsung and Vizio

Most smart TVs watch what you watch. A feature called automatic content recognition (ACR) takes short samples of the picture or sound, matches them against a database and reports the result for audience measurement and targeted ads. Every big TV platform lets you switch it off, but a new study from Northeastern University suggests that on some TVs the switch does less than it promises, Ars Technica reports.

What the researchers did

The paper, Watching the Watchers, looked at 12 TVs from 10 brands running eight operating systems: Samsung's Tizen, LG's webOS, Sony's Google TV, Roku OS (on Roku and TCL sets), Vizio OS, Fire OS and VIDAA, among others. The team ran 5,943 controlled experiments, playing content through the TV's own apps, an antenna feed, HDMI and third-party apps, and recorded where the TVs sent data with tracking switched on and off. The lead author says the systems tested cover about 95% of smart TVs used in the US.

What they found

• Samsung (Tizen): after opting out, traffic consistent with ACR still appeared in all 30 tests with Samsung's own streaming service, 41 of 60 antenna tests and 18 of 30 HDMI tests. Samsung TVs also sent it in 6 of 30 Tubi tests.
• Vizio: traffic to the endpoint the researchers linked to ACR continued in every opted-out scenario, even when the TV sat idle.
• Roku: the opt-out worked for most inputs, but not inside the built-in Roku Channel. Roku's terms say so, and TCL's settings menu discloses it.
• LG, Sony Google TV, Fire TV and VIDAA: no ACR-like traffic was seen after opting out.

The traffic was encrypted, so the team couldn't see what it contained. The authors call it "suspicious" and say it points to potential privacy violations, not proven ones. Ars says it asked Samsung and Vizio for comment.

What you can do

The researchers recommend unplugging smart TVs from the network and using an external streaming device, or relying on the opt-out only where it proved effective. They also published a blocklist of ACR domains for router-level filtering. We've put the menu paths for every major brand in our new guide on how to turn off smart TV tracking, and our TV buying guide explains how to weigh the smart platform when you shop.

Our take

ACR isn't new, and neither are fines over it. What this study adds is evidence that the privacy toggle may not be the end of the story on some of the best-selling TVs. Until Samsung and Vizio explain the traffic, the safest setup is a TV that never gets the Wi-Fi password. It's the same kind of quiet default we flagged in Google's phone number verification on Android.