[unfletch]

This is why ISRC exists. It's like ISBN for recordings, and it's in active use.

http://en.wikipedia.org/wiki/Isrc

A few years back I worked for a startup that was cataloging recorded music. I recall that the major labels would provide us with ISRC, among other things, for all of their recordings. I don't recall whether independent labels and artists used it though. I would guess that it varied.

(See also ISWC, which is for the composition, not the recorded performance of it. ISWC/ISRC is a bit like class/instance.)

[brianwhitman]

Right, ISRC is somewhat useful for glue but is not in wide enough use that it covers the world of music. It also reflects "recordings" not "songs" which actually cause a lot of resolution issues (radio edits, clean vs. explicit and etc.) It also does not help anyone resolve artist names like "The The" when their stopword list turns that into an empty query :)

[jdunck]

This is actually the same issue ISBN faces - it does not refer to a work, but a specific printing, binding, etc.

It is the reason xISBN exists. http://www.worldcat.org/affiliate/webservices/xisbn/app.jsp

Ideally an ID cross-reference would be an open dataset, but it is difficult to achieve that in the market. A proprietary xref is better than no xref.

[plamere]

There's no central database of ISRCs, so even if you have an ISRC in your hand there's no way to find out what artist and song title that ISRC represents.

[guard-of-terra]

You don't need one. Both Spotify and Rdio have ISRCs for their tracks (they got those from the same source), so they can resolve all those cases based on ISRC equality only. How they (or was it Facebook) managed to fail the described cases is beyond me.

As someone who implemented metadata matching of two distinct musical catalogs: First you do search, then you do ranking, then you take the best result. You need to take all the needle metadata (isrc, albums' upc/icpn, title, version, album, artists), and then

- If there are results with the same ISRC, it's cool. Choose the best matching album (by UPC, then by title, then by album version)

- If there aren't, match the track + artist pair and then choose the best matching album for it.

- If you don't have ISRC match and can not match on track title + artist, you should probably bail out.

This way you both won't miss a track in compilation, neither would you prefer The Hit Crew to the actual good performer.

Most international content has ISRC. Local, independent and DIY would probably not. But it's usually easier to match because it doesn't have dozens of different recordings for tracks nor endless realms of compilations.

[jdunck]

Sounds like a business opportunity. Oh, wait, that's what Echo Nest is doing. :)

[parbo]

The exact same track can have multiple ISRC's due to being represented by different labels in different regions.

[unfletch]

There are real-world problems that get in the way here, but that's a misapplication of the spec. A given recording is supposed to be assigned one ISRC. If that recording is released by another entity in another region, it should use the existing ISRC.