Why would you use as camera as the sensor for simple presence detection? An IR LED+photoresistor is much cheaper.
> No one ever worries about the privacy implications of this
Yes, I certainly would be suspicious of both the camera and the attached microprocessor needed to "decide if it's light or dark" from "image data". Anybody that chooses to pay for that kind of massive over-engineering instead of using a cheap IR emitter+detector is trying to do more than just flush the toilet.
> Is Google going to record thousands of hours of sidewalk microphone recordings and store them somewhere?
Why not? It's a trivial[1] amount of data after you apply a simple noise gate and a low bandwidth codec.
You mean... A tiny camera? A photoresistor is a device which measures light hitting it. It's a 1-pixel camera. In exactly the same way a decibelmeter is a little microphone.
My point is, OP is looking for some complicated algorithm to detect and eliminate speech, but you don't need that - you can just eliminate pretty much everything in the first place.
> Why not? It's a trivial[1] amount of data after you apply a simple noise gate and a low bandwidth codec.
5.6kbit/s to record noise levels is like using a CCD camera and a microprocessor for image detection. You could sample the noise level once every 10 minutes, store it in a uint32, and you'd get 5.6kbit/hundred days. You could ship the data over an SMS link. The units could be battery powered and last months.
> Is Google going to record thousands of hours of sidewalk microphone recordings and store them somewhere? Seems far more likely they're just going to stream a "Currently it's 60dB at this intersection"; meets their requirements with minimal bandwidth and infrastructure.
It "seems" to you that Google will actively choose to not record data that would be considered invasive. That's not good enough, though. First, it doesn't seem that way to me at all, I completely disagree with how much data I would expect Google to collect in this situation, and I completely disagree that a dB reading at a lat,lng point will be sufficient for Google's algorithms to do their required work.
Again, the main point I'm trying to bring is not the technical issues, but the societal ones. It is too much surveillance issued directly to a company with no regard for discussing the issues openly. It's just not right.
I am very much not a fan of this project, but I will point out that the problem you're describing has an easy solution; a microphone can record conversations, but the output of a microphone can be fed to an algorithm that never keeps that recording and only records the noise level in dB.
If you've ever used a toilet that flushes itself automatically when you leave, you've been in a bathroom with a tiny camera watching you. No one ever worries about the privacy implications of this, because that tiny camera does nothing with this information except decide if it's light or dark immediately in front of it. The image data isn't stored, it's just thrown away.
Is Google going to record thousands of hours of sidewalk microphone recordings and store them somewhere? Seems far more likely they're just going to stream a "Currently it's 60dB at this intersection"; meets their requirements with minimal bandwidth and infrastructure.