DVD Decoder
Flow of Data in player:
[Notes from Hitachi presentation]
Stage 1: SYNC detection, 8/16 Demodulation, ID Detection.
A total of 8 sync codes are inserted into the 8/16 modulated
channel bitstream representing the current physical sector.
Sync code words are unique in the 8/16 code table (so they
cannot be generated by the 8-to-16 mapping).
The Detection stage looks for sync codes in order to determine
where sectors begin and end. Here the channel bit rate input to
this block is 26.16 Mbits/sec, and output is 13 Mbit/sec.
Stage 2: Error detection and correction
If the check bits (EDC) don't match the fingerprint of
the unscrambled data, the Reed Soloman bytes (IEC) are used to
attempt error correction of the corrupted data. Here the
channel rate output by this block is 11.08 Mbit/sec (~2 Mbit/sec
of error correction parity data, IEC, has been stripped).
Stage 3: Descramble/Decrypt
Data on the disc is descrambled for purposes of further DC
energy reduction. Decryption is performed for purposes of copy
protection.
Stage 4: EDC Check
The fingerprint of the unscrambled data is checked
against the EDC code to verify whether the data was
correctly descrambled.
Stage 5: Track buffer
This FIFO (First In First Out buffer) maps the constant user
data bit rate of 11.08 Mbit/sec to the variable bit rate
of the program streams. DSI and PCI packets (used to control the
behavior of the player) are stripped yielding a 10.08 mbit/sec rate
into the MPEG systems decoder. The mux_rate of all program
streams is 10.08 mbit/sec regardless of actual elementary stream
rates.
Stage 6: Transfer to MPEG system decoder.
Packets are demultiplexed in the system decoder, and distributed
to the respective elementary stream decoders (video, audio,
subpicture, VBI).
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