Podcast #1269: Is Your LG Smart TV Listening to You? and Dolby AC4

On this week's show we look into an article that alleges LG's Smart TVs are listening in on your conversations even when the screen is off. We also do a quick rundown on what Dolby's AC4 is and where you can experience it. We also read your emails and look at the week's news.

News:

• Streaming Is Raising Prices Faster Than Cable Ever Did
• More than half of consumers want live TV and streaming in one package

LG Smart TVs caught listening even with the screen off

Stan from Pittsburg sent us a link to an article (LG Smart TVs caught listening even with the screen off) at FlatpanelsHD claiming LG smart TVs collect more data than many owners realize — including with the screen off.

What the investigation found

• LG TVs use ACR (automatic content recognition): they snapshot what's on screen, including HDMI sources, for ad targeting. FlatpanelsHD notes this has been industry-wide for years, not unique to LG.
• The TVs scan the local Wi‑Fi network, identify other devices, and send back data such as IP address, location, and nearby network names.
• Voice features can transcribe speech after "Hi LG." The mic can stay active 10–15 seconds after silence. Researchers reported recording/transcription even with the display off, and that locally stored data can upload later when the set reconnects (including for a firmware update).
• That last point is presented as conflicting with LG's claim that its TVs "do not collect, record, or store ambient conversations." LG had not commented when the article ran.

Flatpanel's Recommendation

Turn ACR off if you can, or take the TV off the internet and use an external streamer (Apple TV, or Roku.). Firmware can be updated via USB instead of online.

ACR is an old, industry-wide problem and it's unclear why the article focused only on LG. They still argue the mic/network findings are worth attention. They also link their earlier piece ranking Apple TV 4K as stronger on privacy because it doesn't do this kind of viewing tracking.

Update - In a statement sent to Tom's Hardware, LG said "The claims made in the recently published video are not true. LG TVs process voice data only when the voice button on the remote control is pressed and held, or when a wake word such as 'Hi LG' is recognized after the user has activated the Far-Field voice recognition feature. Other than these instances, the TVs do not collect or record ambient conversations. (If the wake word is not recognized, no voice data is transmitted to the server; the audio processing for wake word detection is performed locally on the device and is immediately deleted.)"

Dolby AC-4

One of our listeners, Scott, sent an email asking us to discuss Dolby AC-4 so that is what we are going to do today! Dolby AC-4 is Dolby's next-generation audio codec for broadcast and streaming. It was designed as a clean-sheet replacement for the older Dolby Digital family, not as a tweak of it.

Compared with Dolby Digital Plus, AC-4 aims for similar or better quality at roughly half the bitrate. It natively handles channel-based audio, object-based Dolby Atmos, dialogue enhancement, loudness control, multiple language tracks, and different renderings for speakers vs. headphones in one bitstream. There are several profiles/levels:

• Level 3 — the version widely built into TVs (broadcast/OTT Atmos-style delivery).
• Level 4 — fuller Atmos metadata, including headphone/head-tracking features.
• IMS (Immersive Stereo) — a stereo-plus-metadata flavor used for Atmos music on phones and headphones.

Is it backwards compatible?

No. An AC-4 bitstream cannot be decoded by a Dolby Digital (AC-3) or Dolby Digital Plus decoder. Old AVRs, soundbars, and TVs that only know DD+ (AC-3) will not play AC-4.

What is compatible is the playback path in new TVs and set-top boxes. Those devices decode AC-4 internally, then output whatever the next box needs: PCM stereo, AC-3, DD+, or Atmos over HDMI. So the living-room chain can still work; the codec itself is not drop-in compatible with older Dolby formats. Services that must reach mixed old/new hardware still send DD+ or AAC as a fallback.

Devices that support it

AC-4 decoding is common in UHD TVs shipped since about 2017, especially models that already license Dolby Audio (Dolby has said it is in a large majority of new UHD TVs). Early public commitments came from Samsung, Sony, and Vizio; it is also in many Android TV / Google TV platforms and some Amazon Fire TV devices.

It is not universal:

• Pre-~2017 TVs, most older soundbars/AVRs, and a lot of cheap streaming sticks do not decode it.
• ATSC 3.0 ("NextGen TV") tuners are the main over-the-air path in the U.S.; tuner support is still incomplete across brands and model lines.
• Most consumer AVRs still expect Atmos via DD+ JOC (Joint Object Coding) or TrueHD, not a raw AC-4 bitstream from the source.

Note - JOC allows an Atmos-capable TV, soundbar, or AVR to use the "JOC" metadata to build the immersive mix. An older DD+-only device ignores the extra data and just plays the core 5.1

Studios and television

Broadcast is the main home. AC-4 is an official audio system for ATSC 3.0 in the U.S. and is adopted by DVB in Europe. NextGen TV stations can (and some do) use it for Atmos, dialogue enhancement, and multiple presentations. Immersive AC-4 on U.S. OTA is still uneven; many 3.0 stations have not yet gone full Atmos.

Streaming is later. Netflix, Disney+, Apple TV+, and most other major video services still deliver Atmos as Dolby Digital Plus + JOC. Peacock has publicly committed to AC-4 (alongside Dolby Vision 2), with rollout described as later in 2026. Atmos music already uses AC-4 IMS on several apps.

Studios still master Atmos the same way. The delivery codec is chosen per platform: cinema TrueHD, most streaming DD+ JOC, NextGen TV and a few future streamers AC-4. AC-4 is in the pipeline; it is not yet the default living-room streaming format.