Disc recording methods TAO SAO DAO

CD Recording FAQ
3. Basic notions
  3.2. Recording modes
When writing a cd, you have to determine the mode in which it will be recorded. For example, you may need to gradually add information, or write the whole cd in one go. The options available are:

    3.2.1. DAO (Disc At Once)
This is the preferred mode to record cds. The whole cd is written in one go and data cannot be added at a later time. In this way, the maximum capacity of the cd is used and information about the gaps between audio tracks can be set by the user. DAO offers complete control over the cd layout.

    3.2.2. TAO (Track At Once)
This mode allows to add tracks at a later time. Till finalizing the cd (so that no more data can be added), the cd can be read only in a recorder. There is a gap of 2 seconds between tracks, which contains a few bytes which are heard as noise in some audio players.

    3.2.3. SAO (Session At Once)
In this mode, all information is written in one go (session), but further addition of another session is possible. Within a session, the user has complete control over the cd layout. SAO is a superset of DAO, the basic difference being that with DAO the cd cannot be used for further writing.

    3.2.4. PAO (Packet At Once)
In incremental writing, PAO is utilized so that 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. PAO can't be used for audio.

    3.2.5. Multisession
This mode uses TAO to allow you to add data during several sessions. Each time a session is added, about 15MB of disc space are used for session information. These sessions can be related to each other, so that more recent versions of various feel "substitute" older versions existing in older sessions.

    3.2.6. CUE sheet
This method can be used only with recorders which support the "send cue" command. The cd layout is described in a simple text file which looks like this:

...............
TRACK 01
AUDIO TITLE "Track01"
PERFORMER "Unknown Artist"
INDEX 01 00:00:00
TRACK 02
AUDIO TITLE "Track02"
PERFORMER "Unknown Artist"
INDEX 00 03:27:16
INDEX 01 03:28:50
...............

To describe the cd layout, a simple language with fairly easy syntax is used. Using CUE sheets is only useful when writing audio cds or complex cd layouts.

Though this is not the case with some older models, all these methods are supported by most (if not all) modern drives.