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Comment by walz | Hacker News Reader

I've listened to a bunch of the snippets and you can usually just barely hear the sound in the background. Which makes me think Shazam is very accurate. I really should read more about how Shazam's algorithm works, because it feels like magic.

The phone records 10 minute chunks of audio at a time, in airplane mode. Every 10 minutes, airplane mode is turned off and the audio is uploaded to a server. The server then splits the audio into 15 second overlapping chunks, and each is passed to Shazam's API (no official API, but someone reverse engineered it and made a great Python package). This setup is super power efficient! The phone dips down to a minimum 70% percent battery by the early morning.

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> I really should read more about how Shazam's algorithm works, because it feels like magic.

https://www.ee.columbia.edu/~dpwe/papers/Wang03-shazam.pdf

Also, if you’re more visual, algorithm inventor Avery Wang delivered an accessible and detailed lecture at DAFx several years back:

https://m.youtube.com/watch?v=YVTnj3OIhwI

I found it especially insightful because he started from the beginning and traced the thought process as the algorithm developed and became more sophisticated.

Holy cow.

Just clicked around and you're right: the Sep 29 5:19pm snippet detected "Celebration" by Kool and the Gang, and there's almost nothing there. But it's in there.

Had I not known what I was listening for, and been intentionally listening, there's zero chance I'd have picked up on it.

It does feel like magic.

The battery will live much longer if you run it from 80% down to 50%. There are some clever plugs you can get off the shelf if your phone doesn’t support setting this in software.

I doubt the "design brief" for this involves ensuring it's got thousands or days worth of expected battery charging lifetime.

There's already people here discussing the best way to locate it. Sooner or later someone's gonna find a "free phone" and trade it for a point of meth somewhere just off 16th and Mission...

will be interesting to see how it fares in the winter!

A San Francisco winter? The mean daily minimum is something like 45F, it's more likely to have trouble overheating during the summer.

Less daily solar radiation to power/recharge the phone.

"The coldest winter I ever spent was a summer in San Francisco." -- Mark Twain

I suspect moisture damage from Karl The Fog rolling in every afternoon is more likely to kill it.

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