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CD Recording FAQ
3. Basic notions
3.1. How data are organized on a CD
The surface of a cd consists of a number of sectors. A sector is equal to 1/75 of ione second, and an average cd consists of about 333.000 sectors.
Each sector contains 2352 bytes, which are used to store data and information used when the cd is read back. This information consists of a sync header (hich indicates a new sector), error correction information (which ensures that stored data are appropriately read), and various other headers. Depending on the format used, these elements may not be present, or present at different quantities.
The cd surface as a whole consists of 2 areas, one which is used by the recorder to determine its recording policy and is not visible to the user, and one which is used to store user data. So a cd consists of these areas:
- Power Calibration Area, which is a "test area" so that the recorder can determine the laser power needed. This area can be used up to 99 times.
- Program Memory Area, which is used to store temporary information about track topology till the cd is finalized.
- Lead-In Area, which indicates that a new track starts and contains its Table of Contents (TOC).
- Data Area, where data determined by the user are transferred.
- Lead-Out Area, which indicates that a track ends.
If a recorder fails to access Power Calibration Area and Program Memory Area, then the recording process cannot be initiated and this is a serious indication that there is something wrong with the recorder or the media used.