All about producing and mastering audio for disc, the web and beyond

Wednesday, August 24, 2011

Metadata, ISRC, UP and QC

What is metadata?

Any information that is included within a program, whether it is for a download or creating a disc, that is not the program itself. It is embedded within the digital file (as a download or when burned to disc). Examples are track IDs, start and stop IDs, ISRCs, UPCs, and CD Text information. One of the things that the mastering engineer is responsible for is understanding what these are and including all this information in a master.

What is an ISRC?

It stands for International Standard Recording Code. It is a number that is allocated to any publisher (record label, artist, or anybody that is owns a catalogue of music). It is registered in the USA with the RIAA (Recording Industry Association of America) and in Europe with GEMA (a performance rights organisation) . The code is a unique identifier that gets attached to every single piece of music (each song within a record would have its own ISRC code). Any time that the music is played over the air, downloaded or streamed, the identifier is logged. This is vital in the payment process .

What is a UPC?

It stands for Universal Product Code. Is a number assigned to a product. Traditionally it has been a physical item, such as a cereal box in a grocery store, which has a bar code (and correlating number) to scan at the checkout to identify what that product is. The same is true of CDs or DVDs. But they are also used to track downloads in some cases, so you should register and include it in your product.

What is QC?

This is what is known as Quality Check. Mastering is the final process before distribution. As a result, it is the mastering engineer’s job to make sure that there are absolutely no flaws in the program (a dropout or a click for example). The mastering engineer should give the client assurance that there is no problem with the audio.


  1. Addendum

    There is quite a bit of confusion regarding the source of CD track information in iTunes, Windows Media Player as well as various other hardware and software media players. For the most part there are two primary sources of CD track information utilized by media players: CD-text and online media databases.

    CD-TEXT is an extension of the Red Book Compact Disc specifications standard for audio CDs that was created to allow storage of information such as artist name, album title, track names and so on in the subcode of an audio CD. CD-TEXT has been adopted slowly and support in CD players and especially CD-ROM drives has been inconsistent at best. Some car CD players and many multidisc players now support CD-TEXT (such as your DVD player at home). Many computer-based media players, such as later versions of WinAmp, Realplayer and others support CD-TEXT as long as the CD-ROM drive in the computer also supports CD-TEXT. Many popular computer applications do not utilize CD-TEXT information, most notably iTunes and Windows Media Player. They use a different method to get CD information namely online databases.

    Online databases are used to store CD information as well as other info including album art and lyrics and to provide this data to any device that has access to the database. Each CD profile is created by a ‘fingerprinting’ process involves calculations on track start times, track duration and total length information stored in the table of contents of the CD. If a record for a CD is not found, a new profile could be created and submitted to the database. There are several databases – CDDB, now known as Gracenote (used by iTunes), AMG (Lasso), Muze, freedb and MusicBrainz. Although the CD identification process used by these databases may differ from the original CDDB process, the concept is the same and duplicate, erroneous and multiple entries do occur with some systems (especially in systems that allow user submitted data such as Gracenote & freedb.)

    The information supplied by online databases can easily be confused with similar data stored within MP3 or AAC (iTunes format) files. These files actually do contain metadata in the header of the file (called ID3 tags for MP3's). This information is often supplemented using data from online databases within many applications.

    - What do you do to make sure your listeners can get your CD track information without digging into the liner notes? Assuming that you were careful to notify your mastering engineer of any title changes or typos so that your production CDs contain accurate CD-TEXT information, the next step is to tackle the online databases. Unfortunately every database has a different procedure.

    iTunes - insert your CD, click on the first track and select 'file', then 'get info' and enter the track information. When you have entered all the track information go to 'advanced', 'submit CD track names', fill in the requested information and hit OK.

    Windows Media Player - You must send a copy of your CD to AMG.

    There are many players that reference the freedb database.

  2. Thumbs up guys your doing a really good job.
    click for more

  3. great info but everybody tells about this but nobody tells what software add isrc ? why ?