Metadata
How to Ensure Your MP3s
Are Easily Recognizable

by Mike Wells

Here are a few scenarios you are probably familiar with:

-You buy a CD, bring it home and pop it into your Mac. iTunes opens and shows you all the information about the album. How did that happen?

-You take that CD to work and pop it into your PC. Windows Media player opens, but now the album info doesn’t show. Why not?

-You take that CD into your car, and your fancy new car stereo shows the song titles scrolling by. There it is again. How?

-You just finished creating a CD of your band, but when you put that CD into any of the above methods no information shows up. How do you get that type of info to appear for your band?

The information we’re referring to is called “Metadata” and this article will inform you as to the different types, and explain how to include metadata for your own release.

What are the different types of Metadata, and where does it reside?

1) Within digital asset files (.mp3, etc.) as “tags”

Many digital file formats support a tagging structure known as “ID3,” which stores information to describe the file such as Artist Name, Track Title, and sometimes even Album Art. A tagger application is used to embed/edit this information within the files. Many tagging applications are available as freeware or shareware on the internet for both the Mac and PC platforms.

2) On the internet in “metadatabase” applications

Metadatabase applications are used by the majority of music software programs to provide these applications with information about a CD when that CD is inserted into a computer. To best illustrate this, let’s use an example:

iTunes uses a metadatabase provider called “Gracenote” with an application called “CDDB” (short for “Compact Disc Database”). When you insert a CD into your computer and iTunes starts, the iTunes application sees the CD, and makes a request over the internet to the CDDB application “asking” if it “knows” what CD has been inserted into the computer. If the answer is “yes,” then CDDB returns information about the release (Artist Name, Track Titles, etc...) back to iTunes, and iTunes then displays this information in its main window.
In order for that answer to be “yes” when iTunes makes the initial request to CDDB, the information about the release must have been previously submitted to the CDDB application.

3) Within a CDas “CDText”

CD Text was created by Sony in the mid-’90s, and its support is spotty in the marketplace. While Metadatabases and ID3 tags have gained more momentum in recent years, it’s still good to know how CD Text works. CD Text is the Artist Name, Release Title, and Track Titles of a CD, embedded into the CD itself usually during mastering. The CD Text contained in the master is then replicated at the manufacturing plant when the CDs are pressed. The caveat of CD Text is that the player must support it, by supporting the Sony license and technology to display it. At this point, the main area where CD Text is illustrated is in car stereos.

How can I embed/encode/submit metadata about my release to each of these methods?

1) Embedding metadata into ID3 tags:

As mentioned above, there are many “tagging” applications available on the internet to do just this. If you plan on creating your own Snocap or other music-direct-download store, consider using a tagging application to add metadata to each of your files. Two applications that are easy to use are MP3Tag (PC - www.mp3tag.de/en/) and Tag (Mac - www.sbooth.org/Tag/). Both are freeware (and accept donations to assist support and future development). With these applications, you are able to first create your digital assets (.mp3, .aac, etc.) and then view and tag them.

Some considerations to take into account with ID3 tags: You will notice for each application that there are different levels of ID3 support, and with each come different options (Album Art as a tag, etc.).

If your goal is to ensure the best compatibility for players in the marketplace, it is best to stick to ID3 v1.0 as your tag level.

2) Submitting metadata to metadatabases:

Currently there are four metadatabases in the market worth submitting your information to. They are:
-Gracenote: The largest and most supported
-Muze/All Music Guide: Used by Microsoft’s Windows Media Player application
-FreeDB: An open source metadatabase with large grassroots support behind it
-Musicbrainz: Currently gaining momentum in the metadata marketplace
To have your release information included in each of these metadatabases, you must follow the guidelines supplied by each vendor.

For Gracenote and FreeDB, there are many free applications that will submit information to each metadatabase. The Gracenote and FreeDB websites list applications per-platform that support metadata submission.

Musicbrainz uses a proprietary application to generate “fingerprints,” and then a proprietary submission policy for adding those fingerprints into their metadatabase. See www.musicbrainz.org for more information.

Lastly, the All Music / All Media metadatabase uses a manual submission method where you must submit physical CDs for their review to be considered for the inclusion into their metadatabase, which will then result in the Windows Media Player application recognizing your CD. For information and submission address info, see this webpage: www.allmusic.com/cg/amg.dll?p=amg&sql=32:amg/info_pages/a_product_submissions.html

3) Adding CDText to your release:

If you are having your release professionally mastered, consult with your mastering engineer about adding CD Text to your masters. Chances are he will include CD Text in your final masters for replication. However, the effort to support CD Text does not stop with the creation of the masters. To guarantee CD Text will appear in your manufactured release, you must also speak with the company manufacturing your CD, to see if it supports the replication of CD Text into the final product. While most plants do support CD Text, it is in your best interest to speak with your plant representative to ensure they are aware not only that your masters have CD Text embedded within them, but also that you would like to receive your replicated product back with the CD Text.

Lastly, if your manufacturer offers a test pressing, take advantage of this service. An ounce of prevention...

Testing, Testing...

After you have determined how to include metadata in its various forms, it is in your best interest to test your media to see how your metadata appears.

For ID3 tags, place your tagged assets into as many different players (iPods, SanDisk players, etc.) as you can access, to see how your information will appear.

For metadatabase information, have a look at what applications utilize which metadatabase providers, and then test your submissions through those providers. A great list of metadatabase to applications mapping can be found here:

www.ripfactory.com/rippermetadata.html

For CDText, test your discs in car stereos supporting it (a trip to the car stereo store anyone?)

Conclusion:

With a small time investment, you can effectively learn the scope of metadata quickly and tell people more about your release, thus increasing the visibility of your release.
In a market where gaining visibility is a major challenge, proficiency in metadata moves you much further along towards that goal.

Mike Wells is an audio mastering engineer in San Francisco, Calif. Outside the mastering studio he enjoys motorcycles, working with synthesizers, teaching and annoying software developers. He can be reached at mike[at]mikewellsmasterin[dot].com.