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Comment by grep4master | Hacker News Reader

It would be nice to have the song identification feature on iOS while on standby like the Pixel 2 does.

I still can't understand how that feature works. They stated that everything is done locally on the device, so privacy is not an issue. But how can they host a huge catalog of songs fingerprints without blowing the storage? Are they only saving the top charts?

For what it's worth, here's a bit (and discussion) on how Shazam actually works. I'm ashamed to admit I understand hardly any of it.

http://coding-geek.com/how-shazam-works/ https://news.ycombinator.com/item?id=9870408

It's definitely not just the top charts. Notably it has picked up when someone near me was playing Chopin on a piano as well as the occasional KPop tune my girlfriend is listening to.

My guess is it supplements the data with songs from your Google Music and youtube history.

The Shazam thread from the other day said it was only 60MB worth for like 10 or 20k songs

They only store a catalog of the most popular songs. (Where 'most popular' is determined by your geographical location). This catalog is periodically updated.

Isn't the use case to find obscure music? Weird to have just popular ones. To "discover" a top 10 hit I can just ask someone nearby.

I think the Pareto principal kicks in hard here. If it stores the top 20,000 songs as the other comments suggest then I expect that would include the vast majority of music you’d come across.

Not necessarily. Everything is "obscure" to you the first time you hear it.

Top 10, yes, but not top 10,000.

My understanding is that song fingerprints are tiny, so it's not too prohibitive to store an entire catalog of them on the device.

That's weird, because the AcoustID database is over 160GB: https://acoustid.org/database

Then again, it does have 48M fingerprints, so that's only ~3.3KB/fingerprint. Maybe Google has a decent subset in a reasonably-sized package.

Reports on the Pixel library have it at either the 10k or 20k most popular tracks only. That makes for a reasonably small library.

at 3.3kb it's only about 64mb to store 20,000 songs. If they periodically update that (in the background, on wifi, etc) you'd likely never know. It's basically noise when OS updates are multi-gb.

According to a friend who works at Google, they only store a catalog of ~20k popular songs that updates periodically. Fingerprints are small, so an archive of that size isn't too big.

Sucks for the little guys: http://www.thwink.org/sustain/glossary/CumulativeAdvantagePr...

Yeah it misses out on a lot of indie stuff

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