9
Video and Audio Processing
After the servos have begun, RF data will come from the optical assembly
within the base unit. The “eye pattern” RF data is split into two paths to
provide:
1. Feedback signal to lock the servos; and
2. Video and audio information.
In the A/V processing chain, the RF data is processed by the following
ICs:
Audio / Video Processing ICs
Name IC
Audio
or
Video
Purpose
RF Amp IC001 A/V
(both)
Matrix the optical outputs to produce
signals for servo and A/V circuits
ARP2 IC303 A/V
(both)
•
16 to 8 bit Demodulation
•
Descrambles the main data using
external memory IC304
•
Generates bit clock
Decoder IC401 A/V
(both)
Video
•
MPEG decompression using the
external IC402 and IC403
memories
•
Crops the 16x9 image for a 4x3 TV
picture
•
Controls spindle motor speed
•
Sends disc’s control and menu
data to IC202
•
On screen display graphics
•
D/A Converter (analog video
output)
Audio
•
MPEG audio decompression
•
Dolby Digital AC-3 decompression
using external SRAM IC402 /
IC403
DSP IC501 A
•
Sound enhancements when there
is no AC-3 received (Rear channel
delay)
•
Downmixing of 6 channel AC-3
into 2 (L/R) channels
•
Dolby Prologic decoding
•
Digital coax and optical output
•
Rear channel delay
•
Front/rear level balancing
•
Test tone generation
DAC IC902 A
Digital to analog converter for the front
left and right channels
DACs IC905-
IC907
A 3 Digital to analog converters for the
six AC-3 channels
