CHAPTER 13

724 Chapter 13 Optical Storage
When being written, the sectors are first formatted into data frames of 2,064 bytes, of which 2,048 are
data, 4 bytes contain ID information, 2 bytes contain ID error detection (IED) codes, 6 bytes contain
copyright information, and 4 bytes contain EDC for the frame.
The data frames then have ECC information added to convert them into ECC frames. Each ECC
frame contains the 2,064-byte data frame plus 182 parity outer (PO) bytes and 120 parity inner (PI)
bytes, for a total of 2,366 bytes for each ECC frame.
Finally, the ECC frames are converted into physical sectors on the disc. This is done by taking 91
bytes at a time from the ECC frame and converting them into recorded bits via 8 to 16 modulation.
This is where each byte (8 bits) is converted into a special 16-bit value, which is selected from a table.
These values are designed using an RLL 2,10 scheme, which is designed so that the encoded information
never has a run of less than 2 or more than 10 0 bits in a row. After each group of 91 bytes is
converted via the 8 to 16 modulation, 320 bits (4 bytes) of synchronization information is added.
After the entire ECC frame is converted into a physical sector, 4,836 total bytes are stored.
Table 13.18 shows the sector, frame, and audio data calculations.
Table 13.18 DVD Data Frame, ECC Frame, and Physical Sector Layout and Information
DVD Data Frame:
---------------------------------------------------------------------------
Identification data (ID) bytes 4
ID Error detection code (IED) bytes 2
Copyright Info (CI) bytes 6
Data bytes 2,048
Error detection code (EDC) 4
---------------------------------------------------------------------------
Data frame total bytes 2,064
DVD ECC Frame:
---------------------------------------------------------------------------
Data frame total bytes 2,064
Parity outer (PO) bytes 182
Parity inner (PI) bytes 120
---------------------------------------------------------------------------
ECC Frame total bytes 2,366
DVD Media Physical Sectors:
---------------------------------------------------------------------------
ECC frame bytes 2,366
---------------------------------------------------------------------------
8 to 16 modulation bits 37,856
Syncronization bits 832
---------------------------------------------------------------------------
Total encoded media bits/sector 38,688
Total encoded media bytes/sector 4,836
Original data bits/sector 16,384
Original data bytes/sector 2,048
---------------------------------------------------------------------------
Ratio of original to media data 2.36