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Established 1998

CD/CDR Media Frequently Asked Questions (FAQ)

1. How does mastering differ for CD vs. vinyl?
2. What does Disc At Once/Track At Once mean?
3. What is a cuesheet?
4. What digital audio file formats to you use?
5. Why do CD cases suck?

DAO (Disc At Once)

This is the most common way to record Audio CDRs, and the way they must be done in order to submit them as a CD master. The entire CD is written in a single burning session, with the laser activated and disc rotating the entire time, until it is finished (finalized.) This allows for the maximum capacity of a CD and can allow you to set up different pauses of silences (also known as count-downs or gaps) between tracks, if any at all. DAO offers complete control over the cd layout outside of the Phillips/Sony Red Book standard.

TAO (Track At Once)

This mode isn't very useful for creating a final master, but rather for storing things in progress. It allows you to add tracks to a CDR until it is finalized, but until then the CDR cannot be read by a CD-ROM drive or CD player. There is a standard two second gap between tracks

SAO (Session At Once)

This form writes all information in one session and finalizes the disc, but if there's more storage room, you can add another session. Each session can have complete control with a cuesheet (see below.) SAO is basically a superset of DAO. Note that each finalizing process eats up approx. 40MB on the CDR which cannot be used for audio or data.

PAO (Packet At Once)

This is a format for data CDs and CDRs only, wheere information is transferred on cd in "packets". Each packets consists of a few kilobytes, so that buffer underrun is impossible, and has its own lead-in and lead-out, which take up 7 frames of cd space.

Multisession

This is a Track At Once (TAO) mode that allows you mix multiple data types, such as having an Audio CD with a data session at the end of the disc which can contain text, video or other computer files. It's also known as an "Enhanced CD". There's about 15MB of space used between each type of session to store information specific to each.

A cuesheet is basically a text file in a standard format (usually the Phillips/Sony Red Book one) that contains information about the CD such as the title, artist, and most importantly, information about each track, such as the source file, length, index (number) and the gap (also known as pause or count-down) between each track, if any. You can also define subindexes, pregaps, postgaps media catalog numbers, and other things specific to data CDs. So basically, it lets you specify the "layout" of the tracks on the CD.

It is used to produce a CDR that can be used as a CD master for mass production. You can only use a cuesheet in DOA or SOA modes, and only DOA (Disc At Once) mode can be used to produce a master CDR.

Here's a good article explaining why.