Mastering Audio

Please download our Audio Input technical specification guide (pdf).

• Audio Format
• The Basics
• What is a "one off" CD-R master?
• Program Indexing
• What are PQ codes?
• CD text / iTunes or Media Player artist, song info.
• What about hidden tracks?
• How many minutes can a CD play?
• Do I need tones on my master?
• What about errors and glitches
• Does CDman change the sound of my recordings?
• What if I want some multimedia content at the end of my audio CD?
• Tips on successful CD Mastering
• What about DAT tapes?

Audio Format

The most common question we receive at CDman regarding audio masters is "What format should my audio master be on?"

If you wish to submit your own, final CD-R music master, it must be compatible with all players throughout the world. To test this, you simply have to test your music on old standard CD players, like your car or older home stereo system for example. If your master plays, you are OK to proceed to the factory for replication. Just be aware that most software these days will support a variety of file formats -so just think about compatibility. If you burn a series of WAV files then you need a computer or a special CD player to support the file format. CD Music technically uses: AIF (file format) - 16 bit, 44.1Khz sample rate, stereo. To be compatible, you want to test on old gear. Just be aware that some players have a hard time reading your discs so don't automatically think your file formats are wrong.

• Use multiple machines to test CD-R or DVD-R master discs.
• Do not test your one off (burned) disc on a new CD player that supports WAV , MP3 files unless this is your target audience.
• If you burn computer files (files that won't play on older music CD players, you are technically classified as having a CD-ROM master in the factory, as opposed to a music master.

iTunes, Toast, Windows media, EZ CD Creator Pro, all these software applications are capable of creating both CD-ROM (data files) as well as Red Book compatible (aif) audio discs, so be sure you are creating an audio master and not data files. Note that your disc must be finalized (single session - disc at once) mode and function completely. Use headphones and be sure to test your index points, fade ins and fade outs, listen for clicks, tics, and pops. Skip to the next track and check for 1st beat cut offs. All <source> masters are copied verbatim so test thoroughly!

If you need further assistance please call us at 1-800-557-3347

The Basics

The digital age has given rise to an entire generation that can now record, mix, assemble & pre-master their own CD records right from their own home. While the possibilities are endless, many artists are not aware of the positive impact a professional studio mastering session will have on their project. It is an expensive but worthwhile and highly recommended part of the process. However, your budget and your knowledge of mastering will dictate whether or not this happens. There are many choices for software that you can use to burn masters. One we use at CDman is Peak Bias Pro (google it). It's a great tool to assemble 2 track audio masters for CD replication.

So... using a program like Bias Peak, audio mastering is the art of taking tracks and digitally sequencing, sweetening the EQ, adjust volume levels, checking balances from track to track and then placing them on a finished pre-mastered CD-R one off (or DAT tape) to give to the factory.

CDman is a company that offers audio mastering, so call us any time to discuss your next project.

Standard "Red book" audio discs are defined as this:
 

CD-R "One-off" Masters

CD-Rs discs are now the standard for most users and preferred media format for sending CD plants your audio or data masters. Most advanced home computers now come standard with CD-R disc burners. CD-R discs can be sent directly to the LBR (laser writer at the CD plant). CD-R recordable discs can store up to 700 MB of music, files, multimedia songs - whatever you want!

Many manufacturers of CD-R discs make several models and quality varies widely. It is always a safe bet to buy and use name brand CD-Rs which are sold as their "premium" models. Never use discounted or unfamiliar 'no name' CD-Rs. Seek out a high end audio retailer that sell quality CD-Rs.

Your CD-ROM burner unit must be controlled by a software application via host computer. DO NOT USE STAND ALONE HOME STEREO CONSUMER BURNERS. Most software applications automatically utilize PQ indexing which is simply the song ID, file locations, or song duration etc. - just like a FAT (hard drive File Allocation Table). If your CD-ROM burner requires you to manually PUSH a button to create song ID points then chances are you are NOT using an acceptable CD-R burner.

Most Pro-Audio Recording Studios will have burners. CDman can PQ-encode DAT tapes and non-PMCDs (pre-mastered CDs) when required but accurate track timing cue sheets must be supplied.
 

Program Indexing

The program on the master should be compiled in the correct CD running order. The pause between each track should be of the desired length and without any unwanted noises. We urge you to listen to your master tape or disc in its entirety before sending it for manufacture. CDman may be able to carry out corrections and amendments - but this service will incur additional charges.

PQ Codes

PQ Coding: PQ codes provide location and timing of each track and meta data (like track names) on the CD. The Compact disc contains a number of subcode areas and each area is named with a letter, from P to W. The key subcode areas are named P and Q. The mastering engineer performs PQ coding just before cutting the CD Master (CD-R one off).

How do you know you have successful PQ codes? Simply play the CD-R in a home stereo player (not your computer) and use your 'time display' button to see if it can read the song count backwards (eg: a song that is 3:26 in length will start counting down from 3:26 to 0:00 to indicate the end of the song). Also the 'time display' should indicate the TOTAL playing time of the CD. If your player does not have this display feature then seek out a higher-end player that does this. Also, use headphones to check your PQ codes vs. audio match. It is possible to make errors by placing the index at the wrong moment on the master since it does not affect the audible portion of the song. If you have a hidden track or your PQ codes differ from the artwork (CD jacket) please let us know by including notes with your master so we don't place your job on hold for fear of a mistake at our end.
 

CD text / iTunes or Media Player artist, song info.

CD TEXT adds artist and song title information to standard audio CDs. It requires a CD audio player that supports CD text. Usually you will find these players in cars or multi-disc carousel machines. The players usually have a LCD or LED display window which reads the CD text info from the disc. This feature should not to be confused with iTunes or Media Players on a computer (see below). The CD TEXT information, coded as characters for maximum efficiency, is contained in the R to W subcode channels in the lead-in and/or program area of a CD.

• Lead-in area: text information about the whole disc and individual tracks.
• Program area: text information for the current track including track title, composer, performers etc. The CD TEXT data is repeated throughout each track to reduce the delay in retrieving the data.

With regards to iTunes or Windows Media player running on a computer; once a disc is replicated at CDman all the discs will contain an identical 'fingerprint' id code which will be unique in the marketplace. If you then load up this disc on your computer and run iTunes you can then name the songs, enter artist info, style of music etc. and then use the menu Submit CD Track Names (see image below). iTunes will connect to the CDDB (data base) and attach the song information to the unique fingerprint of your pressed CDs. Since pressed CDs all have the same fingerprint, anyone loading your CD into iTunes will see the track listing information if they are connected to the internet. There is no need to pay anyone extra or do any prior setup for this feature since you can easily take care of this yourself once you receive your discs. Note: iTunes and Windows Media player may access different data bases so multiple submits using each player should be considered.

 What about hidden tracks?

There are two types of ways to make a hidden track on your CD master.

Mode 1: The first (and more difficult) is hiding the track in the discs header file which renders the song invisible to CD players. The only way to hear this song is to start playing the beginning of song one on the disc and then rewind or scroll backwards into the - (minus) region of song one. If you keep rewinding it will eventually get to the beginning of your hidden track. There is no extra charge for us to replicate this feature. CDman can not tech support or assist you in any way to author this feature as it falls outside the normal Red Book guidelines. If you include this feature on your master, please make a note on your order forms (Audio order forms section 13) as well as a note placed inside the jewel case for our mastering engineers;

Master contains hidden track in header file:

(hidden) Song ID#1 ,"Oh Baby" , start -3:05 , end - 0:02
Song ID#1 , "Sha La La" , start 0:00 , end 4:12

---------------

Mode 2: (easy) A hidden track can be as simple as leaving the credits off your artwork to act as a special bonus track. It can play normally with it's own ID point or it can be tagged onto the last song on the CD to make one long song. In any event, please make it obvious to us what you are trying to do. Having a song appear on your CD without visible credits on your liners notes or artwork is confusing and causes us to think something might be wrong with your artwork layouts. So please make notes on your order forms (Audio order forms section 13) as well as including additional notes with your master.

example of track listing notes:

Song ID#11 , "Moon in June" , start 35:17 , end 41:00
Song ID#12 , "This is the end" , start 41:02 , end 48:05 *

* note there is a 2 min. pause at 44:35. At 46:35 a non-credited track called "One more song" begins and will end at 48:05. The total duration of ID#12 is 06:03 which includes two songs.

Or-

Song ID#11 , "Moon in June" , start 35:17 , end 41:00
Song ID#12 , "This is the end" , start 41:02 , end 46:35
Song ID#13 , NOT CREDITED (hidden track) , start 46:35 , end 48:05.

Playing Time of CDs

In the Red Book, Philips recommends that the playing time of a Compact Disc should not exceed 74 minutes 30 seconds. If you exceed this, our glass mastering engineers will have to start compressing the data. This is done in 2 ways:

1. Smaller linear pitch: the gap between each pit is reduced.
2. Tighter track spacing: the space between each track is reduced.

The undesirable effects of doing this would be cross talk (picking up the data from an adjacent track) and thus introducing a degree of distortion or jitter.

Although most newer CD players have advanced optics and circuitry to eliminate these artifacts on long playing discs, the chances of these errors will depend on the quality of the spindle holding the disc. ie: if the player is cheap and it causes the disc to wobble in the player, the greater chance of defects will be audible.

A general rule of thumb is that if it fits on a CD-R then we can replicate it. Some discs can go up to 80 min. depending on the software that burns your audio, but realize that once you exceed red book (74:30) the data tracks will start to compress.

Depending on the circumstances of your track pitch, exceedingly long masters may require a hold be placed on your disc (but be warned that this is not in all cases) and ask that you to sign a waiver to proceed with your replication. If your master is over 74:30 and you wish to avoid potential delays, consider downloading the following PDF, and include with your order forms:

Download Red Book Waiver Form
 

Other notes about your master

Do I need tones on my master?

• A finished pre-mastered CD-R or DAT does not need tones and is digitally transferred without alteration. The highest audio level is referenced to 0 db on a Sony-1630 system.

• CDman digitally transfers your master and tries to listen for errors. However, if an error or glitch is found on your finished CDs we will reference your original master. If it is the fault of our glass master and not your master we will rerun your order free of charge. CDs will not be replaced unless returned COD to us. No CDs may be returned without first obtaining an R.M.A. number

• No! your master is your finished product and we will replicate it exactly as is.

• This is not a problem but your product is then classified as multimedia CD-ROM and must contain TWO SESSIONS on a single pre-master.

• Get your studio recordings mastered by someone good! With the plethora of home computers out there it's easy for anyone (and their dog) to call themselves a mastering facility. Without a sound knowledge (pun intended) of EQ, compression, quantization errors and jitter, you may find yourself getting a CD that sounds worse than the original mix! A talented mastering engineer's job is to "sweeten" the mix, maximize levels with compression and EQ, and make sure your program is successfully transferred from DAT to CD.

• Always ask the studio for a CD-R one-off. This will not only provide proof of accurate indexing of your songs but allow you one last listen to your mixes before you start the mass production process.

What about DAT?

• DAT (digital audio tape) at one point was the a studio standard for transferring your music to the CD plant. With the advent of the CD-R, this tape based format has become less and less popular. With DAT our engineers need to manually program your ID points on the final CD which is not as desirable as a final pre-mastered CD-R. We prefer your studio master to a CD-R final one off and not a DAT.
  
• If you must send a DAT you need to provide a log sheet from the studio. The log sheet must look something close to this:
  
  

  Song Title Index	Start ABS	Duration Of Song	End ABS
  1. My Song	2:00	3:50	5:50
  2. My Other Song	5:52	3:00	8:52

  
   
  ABS = Absolute Time -this is the time code track on the DAT player. When you record your DAT a 'stamp' is placed onto the tape along with your music. You must play back your DAT after recording with the time counter set to ABS mode. Simply look at the time counter as it plays back and write down the information in a table as illustrated above.
  
  
• Start your music at 2:00 -never start recording at the head. Leave 2 minutes of silence.
  
  
• DAT recorders can also record Index or ID points but are very inaccurate. WE CAN NOT USE YOUR INDEX POINTS recorded into a DAT tape. A log sheet must always be used.
  
  HIDDEN TRACKS at the end of your CD must be indicated on the index cue sheet. See example below:

  Song Title Index	Start ABS	Duration Of Song	End ABS
  11. My 2nd to Last Song	45:00	3:50	48:50
  12. My Last Song (includes non credited 'hidden' track)	48:52	10:00	58:52

CDman requests that a CD-R master (and a back-up copy) is sent to us
to ensure an absolute clone of your material. 

Never send your original master. Always keep a back-up copy
of your master yourself for safety and archiving purposes.
CDman cannot guarantee the safety of your master.