Hidden Codes / All about CD Text, ISRC Codes & extended information

What are CD ISRC Codes & CD TextAlthough many people do not realise it, the humble CD can have mystery, sometimes hidden information & code stored beneath that innocent silver surface.  You should know what this information is and how you can use it to your advantage if you’re manufacturing CD’s.

Those who have looked into CD manufacturing and mastering before may have come across the term “PQ Encoded Master Red Book Master”. So what is Red Book and what is PQ encoding? Red Book actually refers to a an actual book that has a red cover, yup that simple. This book was written by Philips & Sony who created the CD format, the book contains information that defines the CD format, it’s like a rule book to make sure all manufactured CD’s are universally compatible with all players.

cd manufacturing | cd printing | cd production

It sets out the physical and data standards that must be strictly adhered to if you wish to press CD’s or create software that creates CD masters. Don’t bother going down to the local library to find a copy of this “Red Book” as it is only available from Philips & Sony, and I believe it costs £ 4000.00. It was never going to be a big seller, but vital if you’re involved in providing hardware or software for the CD industry.

So that’s the Red Book bit, what about the PQ encoding. The letters PQ are not an acronym, they refer to what we call “sub channels” or reserved areas of the disc to hold extended information. The CD format has 8 “sub channels” named P, Q, R, S, T, U, V & W that store this additional information about the disc.

The “P” channel is where CD players look for the start and stop time of the individual tracks. The “Q ” channel describes the time coding of the disc, so when you see the time of the track on the display of a CD player, this comes form the “Q” channel. So basically PQ encoding is the information CD players use to find the start and end of the tracks and states the absolute time of the music, so not really that mysterious.

It is the other sub channels (R to W) and the table of contents (TOC) that will be of interest to most people. These can hold a variety of information that you will find useful.

CD Text.

CD Text

You may have noticed in some CD players it includes the artist and track title on the display whilst playing the disc, this is “CD Text”. You can actually store much more information than this, you can have the name of the “Songwriter”, “Composer”, “Arranger” and a “Message”.

I have always thought that the “Message” area would be more widely used. It is great place to store “Easter Eggs” or hidden information for listeners/ readers to find, especially things like links to websites to download additional information, bonus tracks and live versions of the track. These can be really popular with fans and create a little buzz on forums.

The message line can hold up to 160 characters, does this sound familiar? Yes, this is old skool twitter. So the humble CD has been tweeting before twitter was ever dreamt of. I really think it would be a cool idea to do use this as a theme for a CD. So who is going to be the first to have a fully tweeted CD. If it has been done before, I would love to know!

One word of warning about CD text, as this is encoded in your master, if after the mastering stage you decide to change the name of any tracks, the master will need to be re-made with the new track names encoded. Another thing you should watch out for is that CD recording software sometimes uses the “file name” of the data files as CD text. Quite often I will check a Production Master and it will have CD text encoded with things like “Hold On – 2nd Mix Vox higher mastered”, so if you don’t want this information on the master make sure that writing CD Text is not enabled,  if you are not sure how to do this, correctly name the tracks in the play-list to be sure you do not have any misinformation on the disc.

It is quite common these days for people to play CD’s on laptop and desktop computers and to copy the tracks to portable music players, so you would think this would be the perfect use of CD text. Obviously Apple &  Microsoft don’t believe in using this ready available embedded code that we have spent precious time adding to the masters.

No rather than taking the information from the “horses mouth” they go through a convoluted system of taking the number of tracks on a CD, the running times of the tracks, and then comparing this information to a database of existing CD’s. Now most of us have put CD’s into itunes and it comes up with the wrong information. This is because that with of all of the CD’s that have ever been released, it is not that improbable you might find more than one or two that have the same number of tracks and running time, so this is where the problems stem from.

As far as I am aware, the reason they do this is that you can’t guarantee all CD players can read CD text. But if the CD drive is capable of reading CD text, and nearly all are, why not compare this text to the database, if you know the answer I would love to hear from you in the comments section. So if you get your order back from the CD pressing plant and it does not come up with the correct information in itunes, don’t be too quick to blame your CD manufacturer……..

ISRC Codes

So what is an ISRC code, well it stands for International Standard Recognition Codes. This is a Code that conforms to an International Standard for Recognition of a CD :-) In all seriousness think of it as a barcode for each individual track on a CD, a unique identifiable code that can be linked to a piece of music. These codes are used by broadcasters (radio stations and TV company’s) to automatically log which tracks have been played and for how long, this simplifies the process of calculating royalty payments. So if you have spent a large amount of money recording and releasing a CD it makes sense to make sure you get the money that is owed to you.

We have one client who received no royalties for years for one of his CD’s, then all of a sudden he started to receive small but regular cheques. It turns out that a small radio station in Norway had discovered his music and began regularly playing a particular track. Thanks to the ISRC codes he got enough money for a good few slap up lunches, and found a local distributor to sell a bunch of albums in a new market.

You might be thinking that getting these codes must be difficult or expensive, well actually they are free, and it only takes an email or a phone call to get hold of them. In the UK the PPL are responsible for allocating ISRC codes, you can phone them on 020 7534 1122 or if you would prefer to email them member.info@ppluk.com. You will also find more information on the website.

You will be issued with a 3 character Alpha Numeric code that is your registrant code, this will be something like PU3, this is your and yours only. The full ISRC code is made up of 12 letters and numbers, the first part of the code is identifying the country of origin, for Great Britain this is GB, easy enough. The next part is for the year, this is a 2 digit number, so for 2010 the number “10”, for 2011 the number is “11”, still with me? The final 5 digits are numbers and are for you to choose, most people start with 1 and work up from there.

I have a preferred system for using ISRC codes, and as this is an entire subject all of it’s own I will create a further blog to cover this in detail. But until then starting at 1 and working your way up is a good system.

CD Barcode

The last of our hidden codes is the barcode number, we all know that barcodes are essential for distribution and retail.  To be honest as far as encoding on CD masters is concerned I really don’t think they are that important at all.

I don’t know of anyone who actually uses this information when encoded on the disc. The CD pressing plants use the catalogue number to identify parts in manufacturing, distributors & retailers scan the barcode from the packaging and broadcasters use the ISRC codes as mentioned above. This capability of adding the barcode to the subcode might have been one of them things that was done in good faith but not properly thought through, but I am more than happy to be corrected.

So that brings us to the end of the hidden codes. Some of these codes you can have fun with (go on add a link to this blog on your CD message). Some might help you to find out if you are the next hot thing in Timbuktu, and earn you a fortune (get that ISRC now!). But armed with this information, go out and be creative, earn money, and feel free to comment or disagree with anything I have written.



cd manufacturing | cd printing | cd production

3 replies
  1. Lynda Curtis
    Lynda Curtis says:

    Hi I have been reading a lot about ISRC Codes recently and you seem to be able to explain things in a way i can understand. This is my question: My friend made a short film and added music from CD’s. We need to find the ISRC Codes for these songs in order to pay royalties. Is there anywhere these codes are collected, like a directory, or can we get the info from the CD cover. Or will we have to buy each album to get the code of the CD?


    • Kevpure
      Kevpure says:

      Hi Lynda, in the UK the PPL handle the ISRC database, you can email them repertoire@ppluk.com and give them as much information about the tracks as possible and they should be able to give you the ISRC codes to embed in the video. Hope this helps.



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