Sectors

Data Sector Configuration

The 2064 byte sector is, for purposes of error correction, organized into 12 separate rows, each with 172 bytes. The first row starts with the 12 Byte sector header (ID, IEC, Reserved bytes), followed by the remaining data bytes. The following 10 rows contain only data. The final row is punctuated with a 4 Byte field (EDC).

Row Fields within row --- ---------------------------------------------------------------------- 0 ID (4B) IEC (2B) RESERVED (6B) Main data (160 Bytes: D[0] - D[159]) 1 Main Data (172 Bytes: D[ 160] - D[ 331]) 2 Main Data (172 Bytes: D[ 332] - D[ 503]) 3 Main Data (172 Bytes: D[ 504] - D[ 675]) 4 Main Data (172 Bytes: D[ 676] - D[ 847]) 5 Main Data (172 Bytes: D[ 848] - D[1019]) 6 Main Data (172 Bytes: D[1020] - D[1191]) 7 Main Data (172 Bytes: D[1192] - D[1363]) 8 Main Data (172 Bytes: D[1364] - D[1535]) 9 Main Data (172 Bytes: D[1536] - D[1707]) 10 Main Data (172 Bytes: D[1708] - D[1879]) 11 Main Data (172 Bytes: D[1880] - D[2047]) EDC (4B) ID: Identification Data (32-bit sector number) IEC: ID Error Correction EDC: Error Detection Code

From the original Toshiba DVD proposal (circa Spring 1995), the following three items changed:

  • sector information in ID
  • EDC Generation Method
  • Initial Value of Main Data Scrambling

    EEC Block Configuration

    To combat bursty errors characteristic of CD-ROM, 16 sectors are further interleaved together, forming a block of 192 rows (16 sectors * 12 rows/sector = 192 rows). Error correction bytes are concatenated to the data block in a 2-dimensional fashion (hence the term "product" in the phrase "Reed-Soloman product codes").

    Specifically: at the end of each row, 10 bytes of RS data are added, hence the RS(182,172,11) vector. At the end of the block, 16 rows of RS data are added (hence the RS(208,192,17) vector). Therefore out of 37,856 total bytes (182*208) for the interleaved block of data, only 33,024 bytes (192*172) or roughly 87% is payload.

    <----- data block -----------> <---------- P1 --------------> D B[ 0][ 0] ... B[ 0][171] | B[ 0][172] .... B[ 0][181] a B[ 1][ 0] ... B[ 1][171] | B[ 1][172] .... B[ 1][181] t . | a . | . | B[190][ 0] ... B[190][171] | B[190][172] .... B[190][181] B[191][ 0] ... B[191][171] | B[191][172] .... B[191][181] -------------------------------------------------------------- B[192][ 0] ... B[192][171] | B[192][172] .... B[192][181] . P . 0 . B[207][ 0] ... B[207][171] | B[207][172] .... B[207][181] P0: RS(182, 172, 11) P1: RS(208, 192, 17)