
8-10
System Stream Decoding and Synchronization
Final Rev F
Copyright 1996 by LSI Logic Corporation. All rights reserved.
Table 8.3
Audio and Video
DTSs and PTSs
8.4
L64005
Synchronization
Resources
The L64005 device includes several hardware resources that assist the
external system with audio and video synchronization. Note that the
L64005 does not synchronize the audio and video by itself. It provides
timing and event information, as well as facilities to control the audio and
video rate. The external system can read internal status registers when
it receives interrupts, and may program video and audio control registers
to close the control loop. The control loop is deliberately left open to allow
for increased exibility.
The L64005 synchronization resources include:
A 16-bit local system clock reference counter. The counter is clocked
at 90-KHz when the input clock to the L64005 is 27-MHz.
A16-bit comparator and register that can generate an interrupt when-
ever the value programmed in the register matches the value of the
16-bit local counter.
A 16-bit counter that generates an interrupt when it wraps around.
The external host processor can count more bits and implement a
full precision, 33-bit counter if necessary.
Figure 8.3 shows block diagram of the local counter and comparator
logic.
Video Access
Unit
Audio Access
Unit
DTS
VIDEO
PTS
VIDEO
PTS
AUDIO
1I
1
18900
22500
4P
2
22500
33300
24660
2B
3
26100
26820
3B
4
29700
28980
7P
5
33300
44100
31140
5B
6
36900
33300
6B
7
40500
35460
10P
8
44100
54900
37620
8B
9
47700
39780
9B
10
51300
41940
13I
11
54900
65700
44100
11B
12
58500
46260
12B
13
62100
48420