Audio Engineering

Video Synchronization 827

position specifi ed for the start of the digital active line: the fi rst digital fi eld starts at 24
words before the start of the analogue line No. 1. The second digital fi eld starts 24 words
before the start of analogue line No. 313.

28.8.1.2 Video Timing Reference Signals (TRS)

Two video TRS are multiplexed into the data stream on every line, as shown in Figure
28.10 , and retain the same format throughout the fi eld blanking interval. Each timing

Analogue line blanking

T: Clock period 37 ns nom.

SAV: Start of active video timing

reference code

EAV: End of active video timing

reference code

(^0) H
24T (625)
32T (525)
288T (625)
276T (525)
1440T
4T
Digital line blanking Digital active line
1488T
Video data block
TV line63.5^64 μμs (625)s (525)
Digital line
1728T (625)
1716T (525)
4T
S
A
V
E
A
V
L
A
V
16T (625)
8T (525)Nom. 20T (625)
10T (525)Nom.
(^0) H
Multiplexed video data
CRY CRY CRY ...
Figure 28.10 : Relationships between timing in digital and analogue TV.