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I work at Google and I'm a long time hobbyist Android developer. I have a lot of non-technical friends ask me about this. What I always say is that this would

by habosa 9y ago

I work at Google and I'm a long time hobbyist Android developer. I have a lot of non-technical friends ask me about this. What I always say is that this would not be possible. To constantly listen for audio, process it, and upload the results would use so much data and battery that you'd notice. Only a plugged in laptop/desktop could get away with this. Am I wrong? Would it even be technically feasible for Facebook to listen all the time?

sattoshi 9y ago
"OK Google" seems to handle it.
- deleted 9y ago
  [deleted]
- habosa 9y ago
  I'm pretty sure it's optimized to listen for a single hotword and then initiate the network connection to process what comes next. What people accuse Facebook of doing would require constant processing of the audio stream for random interesting tokens. Either process on device and then send metadata (more battery, less network) or send the raw stream and process on the server (less battery, more network).
flukus 9y ago
> To constantly listen for audio, process it, and upload the results would use so much data and battery that you'd notice. A few years ago I uninstalled the official facebook app because it was using all of my battery and a fair bit of data, even when I wasn't actively using it. The battery usage record in the settings indicated the facebook app was the cause. After removal it felt like I'd bought a new phone, everything was running so much faster. I recommended the change to friends who saw similar results. I don't know if it was maliciousness or incompetence behind the battery usage, but it would seem that you can get away with it largely unnoticed.
AndrewUnmuted 9y ago
There's no reason the application must always be listening. Facebook could do their voodoo to determine when during the day you are most likely to be in a social atmosphere, and begin listening to the microphone only during that range of time. Processing and uploading doesn't have to happen all at once. They could analyze/process the audio while you're asleep. The power drain would be negligible - or completely unnoticeable if your phone is charging while you sleep. Data obtained from these processes could be uploaded in chunks, hidden inside the photos and videos you upload from the Facebook app. So, in my opinion, not only is this all possible, it'd be not too difficult for Facebook to hide it from the general public.
pdkl95 9y ago
> would use so much data You shouldn't assume that and actually do the math. GSM-HR (an early 90s codec that is fast to encode and designed to be low-power) combined with a trial noise gate will only require[1] uploading <100 kB/hr. > Only a plugged in laptop/desktop Audio compression existed before MP3/AAC. GSM-HR only uses 5.6 kbit/s, and was designed to be encoded on early (GSM) cellphone embedded CPUs/DSPs. Modern devices have several orders of magnitude more CPU/power/bandwidth available. > all the time It's only necessary to record when voice is actually present. A trivial noise-gate[2] will cut the recording time down to only a few percent of the time at most. Obviously a better filter should be possible. [1] https://news.ycombinator.com/item?id=16346416 https://news.ycombinator.com/item?id=16346416 [2] https://en.wikipedia.org/wiki/Noise_gate https://en.wikipedia.org/wiki/Noise_gate
deleted 9y ago
[deleted]
edf13 9y ago
This "I work at Google" thing... doesn't give instant knowledge on all areas. There are many ways this could be covered, as many have said here (Above & Below). Noise gates... other Apps listening for key phrases etc. E.g. A Fitness App could be installed with a noise gate + setup to listen for specific fitness related terms... that triggers a simple pules to say person A is interested in that topic.... Another App does the same for topic B... and the list goes on... That's just off the top of my head. (I don't work at Google)
stordoff 9y ago
I've tested it on my own phone (Lumia 920), and a background audio recording uses about a half to a quarter as much power as the Gmail (IMAP) app - it's pretty negligible. Compressing it to send over the wire might use more (I was recording to WAV), but with the right choice of codec (e.g. GSM-HR as mentioned below) I can't see it adding all that much. A common complaint is that the Facebook app uses a lot of battery anyway, so the costs of audio recording probably _could_ (I doubt they _are_) be buried in that.

by habosa 9y ago

sattoshi 9y ago

"OK Google" seems to handle it.

deleted 9y ago
[deleted]
habosa 9y ago
I'm pretty sure it's optimized to listen for a single hotword and then initiate the network connection to process what comes next. What people accuse Facebook of doing would require constant processing of the audio stream for random interesting tokens. Either process on device and then send metadata (more battery, less network) or send the raw stream and process on the server (less battery, more network).

flukus 9y ago

> To constantly listen for audio, process it, and upload the results would use so much data and battery that you'd notice. A few years ago I uninstalled the official facebook app because it was using all of my battery and a fair bit of data, even when I wasn't actively using it. The battery usage record in the settings indicated the facebook app was the cause. After removal it felt like I'd bought a new phone, everything was running so much faster. I recommended the change to friends who saw similar results. I don't know if it was maliciousness or incompetence behind the battery usage, but it would seem that you can get away with it largely unnoticed.

AndrewUnmuted 9y ago

There's no reason the application must always be listening. Facebook could do their voodoo to determine when during the day you are most likely to be in a social atmosphere, and begin listening to the microphone only during that range of time. Processing and uploading doesn't have to happen all at once. They could analyze/process the audio while you're asleep. The power drain would be negligible - or completely unnoticeable if your phone is charging while you sleep. Data obtained from these processes could be uploaded in chunks, hidden inside the photos and videos you upload from the Facebook app. So, in my opinion, not only is this all possible, it'd be not too difficult for Facebook to hide it from the general public.

pdkl95 9y ago

> would use so much data You shouldn't assume that and actually do the math. GSM-HR (an early 90s codec that is fast to encode and designed to be low-power) combined with a trial noise gate will only require[1] uploading <100 kB/hr. > Only a plugged in laptop/desktop Audio compression existed before MP3/AAC. GSM-HR only uses 5.6 kbit/s, and was designed to be encoded on early (GSM) cellphone embedded CPUs/DSPs. Modern devices have several orders of magnitude more CPU/power/bandwidth available. > all the time It's only necessary to record when voice is actually present. A trivial noise-gate[2] will cut the recording time down to only a few percent of the time at most. Obviously a better filter should be possible. [1] https://news.ycombinator.com/item?id=16346416 https://news.ycombinator.com/item?id=16346416 [2] https://en.wikipedia.org/wiki/Noise_gate https://en.wikipedia.org/wiki/Noise_gate

deleted 9y ago

[deleted]

edf13 9y ago

This "I work at Google" thing... doesn't give instant knowledge on all areas. There are many ways this could be covered, as many have said here (Above & Below). Noise gates... other Apps listening for key phrases etc. E.g. A Fitness App could be installed with a noise gate + setup to listen for specific fitness related terms... that triggers a simple pules to say person A is interested in that topic.... Another App does the same for topic B... and the list goes on... That's just off the top of my head. (I don't work at Google)

stordoff 9y ago

I've tested it on my own phone (Lumia 920), and a background audio recording uses about a half to a quarter as much power as the Gmail (IMAP) app - it's pretty negligible. Compressing it to send over the wire might use more (I was recording to WAV), but with the right choice of codec (e.g. GSM-HR as mentioned below) I can't see it adding all that much. A common complaint is that the Facebook app uses a lot of battery anyway, so the costs of audio recording probably _could_ (I doubt they _are_) be buried in that.