What ACR is and why it is in your TV

ACR stands for Automatic Content Recognition. It is the feature that identifies what is being shown on screen.

How it works

The television takes periodic samples of what appears on screen — frames, or their acoustic fingerprint — and compares them against a database of identified content. It does not send the image: it sends a fingerprint representing it.

The important consequence: it works with any source. Broadcast, streaming, a DVD, a console, a laptop over HDMI. The television does not need to understand where the signal came from to recognise what it is.

What it is used for

• Audience measurement, sold on to the industry.
• Targeted advertising within the television itself.
• "Personalised" recommendations.
• Aggregate data traded with third parties.

It is by a distance the most profitable feature of a modern television for the manufacturer. It explains how televisions can be sold below cost.

How to tell whether yours has it

Look through the package list:

adb shell pm list packages | grep -iE "acr|samba|inscape|audience|content.*recognition"

Samba TV and Inscape are two of the most widespread providers, and they turn up on televisions from several brands.

In the settings, ACR is almost never called ACR. It is called:

• "Viewing information"
• "Content recognition services"
• "Improve recommendations"
• "Live Plus" (LG)
• "Viewing information services" (Samsung)

How to switch it off

From the settings, if your television offers it. That is the first thing to try and it works in most cases.

By removing the package, if it is an Android TV and you have identified it. ACR packages are rarely a dependency of anything, so they usually come off cleanly.

By filtering the provider's domains at the router.

The legal detail

In the EU, ACR requires informed consent under the GDPR. In practice, that consent is collected on a screen during initial setup where almost everyone presses "Accept" to get to watching television.

That it is lawful does not make it what you wanted. And you have the right to withdraw that consent whenever you like: which is exactly what you are doing when you switch it off.