You need special software to use a CD-R/RW drive to write, or record, various types of data onto a CD-R/RW disc (hereafter referred to as "a disc."). This software is called writing software.
Here, we explain about writing software, what software is necessary for which types of recording, and formats.
When only a single recording session (lead in/data/lead out) is to be recorded onto a disc, it is called "Disc-At-Once."
When using Disc-At-Once, no additional data can be recorded onto the disc, even if there is available capacity.
The advantage of this method of recording is that it enables creation of discs that can be played back on almost any CD player or CD-ROM drive, because there are no links inserted between the data tracks.
This method can also be used to create a premastering disc to be taken to the factory.
Note that some CD-R/RD drives do not support this method of recording.
When many sessions are to be recorded onto a disc, it is called "Track-At-Once." If there is space available on the disc, additional data can be recorded onto it.
The advantages of this method include being able to record additional sessions onto a disc, and using it as a CD-ROM of back up data. (Refer to "Multisession.")
A maximum of 99 tracks can be recorded onto a single disc, enabling one or more tracks to be recorded per session. A single disc can only have 30 sessions recorded onto it, because a region of the disc is used every time a session is recorded.
This method is supported by the majority of CD-R/RW drives.
One characteristic of CD-R/RW drives is that once recording commences, the track must be recorded onto the disc in one operation, at the same time the data is transmitted from the host to the drive, uninterrupted at a fixed speed.
This differentiates CD-R/RW drives from other devices, when they are used as external memory devices, and improvements in this area are necessary.
The Packet Write recording method was developed for this reason, and there are many drives available that support it. It differs from Track-At-Once or Disc-At-Once in that data is recorded in small fixed sectors of 64kbytes, known as packets.
A number of formats, such as UDF and CD-R FS, can be used when recording using the Packet Write method.
The advantages of this method are elimination in overhead per session and the elimination of buffer underrun errors. This method, however, cannot be utilized for audio data.
The recording of lead-in/data/lead-out is referred to as one session. The Disc-At-Once method is also referred to as "Single Session," because the disc is only recorded on once. A disc that has had multiple additional sessions recorded onto it using the Track-At-Once method is called "Multisession."
Despite the fact that the Multisession method is extremely convenient for recording more than once on a disc with it. Approximately 10 to 20MB are allotted as session data by each session in Multisession, irrespective of the data actually recorded. The Packet Write method eliminates this session overhead. (Refer to Packet Write, above.) Audio CD players and early-generation CD-ROM drives are not configured to support Multisession, so they cannot read from the 2nd track onwards on a Multisession disc.
This is the format based on the standards defined in the Red Book, established when the Compact Disc came into existence for audio use. The format defines recording of a maximum of 74 minutes of stereo, 16-bit, 44.1KHz sampling audio data. It is fundamentally used to be played back on audio CD players, and was not intended for Multisession data.
You need to prepare a sound file beforehand that meets the standards, to record an audio disc using writing software. The WAV format is used as the standard for Windows and the AIFF format for Macintosh.
ISO9660 is the format that makes it possible to record data on multiple platforms, such as Windows, DOS, Mac OS and UNIX. Windows CD-ROMs use this format as the CD standard format.
The characters that can be used in ISO standard file names were specified with the aim of developing a common standard; they are limited to capital letters, numbers and underbar, 8 characters in length with a 3-letter extension; less than MS-DOS. The number of directory levels is also restricted to a maximum of 8. ISO9660 has the advantage of allowing graphic and other generic data to be used on Windows, Macintosh and other platforms.
The ISO9660 specifications feature a provision for extendibility, and a variety of extended specifications are being provided by various OS vendors.
[Varieties of ISO Extended Specifications]
- ISO9660 Apple expansion
This format was developed by Apple, and extends ISO9660 to permit resource forks (document font data, etc.) to be written into Macintosh files. This means that it can be used the same way as HFS, because it saves the type and creates information necessary to link files and applications. It is possible to share data with Windows.
This is the ISO9660 extension that saves UNIX file information, developed by the Sun Microsystems group.
This is the ISO9660 extension developed by Microsoft, which enables the correct recognition of files across the Windows 95, Windows NT 4.0 and MS-DOS platforms. Each file has a short name for MS-DOS, and a Unicode long name for Windows95/NT use.
HFS(Hierarchical File System)
This is the Macintosh only platform and is the original file system standard for Macintosh hard disks. Macintosh did not initially adopt a hierarchial structure and the system was called MFS. HFS is organized into levels using folders, meaning CD-ROMs can be used in the same way as a hard disk.
It cannot be read by Windows because it is the Macintosh characteristic format.
This format is the standard for Macintosh, the same way as data is shared between Windows, DOS and other platforms.
This is a format that incorporates both ISO9660 and HSF on one disc, which can be used on both the Windows and Macintosh platforms.
It enables the effective usage of one disc on different platforms, because one segment of the recorded data can be specified to be shared by the ISO9660 and HSF sections.
Hybrid discs are mostly created on Macintosh, because Windows cannot fundamentally support HFS.
CD Extra (also called Enhanced CD)
"Mixed Mode" was the format that originally mixed audio and file data. The Red Book standard audio data is forcibly recorded after the file data, because this format is based on the Yellow Book, which defines the use of computer data. As a result, problems, such as noise, occur whe the disc is played back on an audio CD player.
"CD Extra," eliminates the problem of the Mixed Mode, by recording the audio data first, followed by the file data, so that the file and audio data can be effectively saved together. This is a relatively new format defined in 1996.
CD Extra is fundamentally the same as conventional audio CDs, in that it is based on the Red Book for audio CDs. An audio CD player normally only recognizes the 1st session, hence, it will only recognize the 1st session, which contains the audio tracks, of a CD Extra disc.
The data segment of the 2nd session is mainly for use on computers, and plays back the graphic text, and the photo data, etc., related to the artist in the audio segment.
The Electronic Book is a system in which characters, graphics and sound are written onto an 8mm CD, and is mainly used for dictionaries or information databases. It is based on the "Electronic Book Agreement," which defines the data format and search methods. All titles produced using the Electronic Book standard can be operated the same way.
There is a possibility of recording errors occurring on the disc when recording due to delays in reading data. A buffer underrun error is one type of such error.
An "Image File," which allows the data to be transferred to the CD-R/RW as-is, is temporarily created on the hard disk to prevent these errors.
Transmitting from this Image File enables problem-free writing.
The Image File is about the same size as the file data to be recorded, so you will need have more than the same amount available as unused space on the hard disk.
The majority of writing software is capable of creating and saving image files.
You need to have a large volume of unused space on the temporary hard disk when creating an image file.
The method that reads the data directly from its original location and records it onto the disc, preparing only the minimum amount of information, is called "on-the-fly."
The task can be completed using only a small amount of hard disk space.
There is, however, the possibility of a transfer speed error occurring due to a slow hard disk or CPU.