Regular pairing, advertising and control likley use Bluetooth LE for simplicity and battery life. Streaming or transferring video likley use Bluetooth classic for increased bandwidth.
These are two different protocols with different radio behaviour.
So beyond detecting the glasses themselves, which seem like the focus of the project; detecting recording is feasible at the point of transfer to a phone.
The issue is distinguishing it from any other high bandwidth Bluetooth device nearby, such as headphones.
They don't stream to your phone when taking a video or picture. The data is on device and transferred later. It also uses wifi direct not BLE. It seems many many people on HN have absolutely no clue how the meta glasses work lol, there's barely any accurate information in this thread.
Like I mentioned in the text, I haven't looked into Wi-Fi yet. The picture/video -> transfer through the app is correct, and why an alternative method for detecting actual recording is necessary, but I'd expect to see that most events like battery status updates would be over directed BLE, since the initial boot + battery status is broadcast. And likely BTC for streaming audio. I'm unfamiliar with Wi-Fi Direct specifically, are you familiar with the process of scanning for active Wi-Fi Direct services?
Sorry don't mean to demean your effort, I read the GH post and like the hacker spirit :D. It's the rest of the people in the HN comments with 0 clue.
I like my glasses and don't really agree with your goals (nor see the point of letting you know when someone's wearing them; in my city your device would be beeping constantly) so I'm not interested in helping unfortunately. But I do wish you luck, as I said I like the spirit.
These are two different protocols with different radio behaviour.
So beyond detecting the glasses themselves, which seem like the focus of the project; detecting recording is feasible at the point of transfer to a phone.
The issue is distinguishing it from any other high bandwidth Bluetooth device nearby, such as headphones.