Barcodes are machine-readable numbers used as stock control mechanisms by retailers: as such they are highly standardised and well recognised, and form an invaluable identifier for communication between companies.
There are many different types of barcode but the usual ones are Global Trade Item Numbers (GTINs). The most common types of GTIN are:
- Universal Product Code (UPC), which is the original barcode used in North America. They are 12 digits long, but any number of zeros at the start can be left off, so the actual printed barcode can be shorter than this.
- European Article Number (EAN) also known as Japanese Article Number (JAN), which is widely used in the rest of the world. The 13 digit type (EAN-13) is the most common, although there are others such as EAN-8. A UPC can be turned into an EAN-13 by adding a leading zero.
Reasons for Adding Barcodes
- Barcodes are an industry standard for identifying products. Adding barcodes makes the MusicBrainz data much more accessible and useful for a variety of organisations, from wholesalers and retailers to public libraries. Some of them might be prepared to license the MusicBrainz database.
- Barcodes are clear, visually distinct, well recognised, almost ubiquitous, and are generally unique to a specific release. This makes them a really useful way to help amateur cataloguers be precise about exactly what they are talking about, even if they don't understand the full subtleties of re-releases, regional variations, catalog numbers, and so on.
- Using a barcode makes it easy to match a MusicBrainz release to an Amazon ASIN. This adds cover art to releases, and earns MusicBrainz money through referral fees.
- USB barcode scanners are cheap and can be an easy way to manage large collections of music.
You're in luck if you have the physical media and there's a barcode printed on it. When doing research on releases you don't own, it's often hard to find the right UPC/EAN. Here are some tips to help you out.
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- Many western labels use parts of barcodes for catalog numbers, or rather catalog numbers in barcodes.
- The last digit is always the checksum. You can easily calculate it using an on-line tool.
- The digit just before the checksum often stands for media type. E.g. many EMI sublabels often use these: 1 - LP, 2 - CD, 4 - MC, 6 - 12" vinyl, 7 - 7" vinyl, 8 - MD. If you have one barcode, you can try changing the type digit, recalculating the check digit and googling for the new barcode. But also note that different media types sometimes contain different track lists. E.g. LPs are sometimes shorter than CDs.
- If all you have is a catalog number, and you think it's part of a barcode, look for releases from the same years, artist and/or label with similar numbers. You'll often find many releases have the same barcode prefix, so all you'll have to do is prepend the prefix to the catalog number, add the type digit (if needed), calculate the check digit - and you're done.
- Release Catalog Number
- Label Code (Note: for labels, not albums)
- ISRC for recordings (single tracks)
Also see http://www.iasa-web.org/icat/08_0.htm for some others.