DigitalVideoAndHDTVAlgorithmsAndInterfaces.pdf

Figure 15.2 Rec. 656 component
digital interface uses
EAV to signal the start of
each horizontal blanking
interval, and SAV to signal
the start of active video.
Between EAV and SAV, ancillary
data (HANC) can be
carried. In a nonpicture line,
the region between SAV and
EAV can carry ancillary data
(VANC). Digitized ancillary
signals may be carried in lines
other than those that convey
either VANC or analog sync.
0 V
EAV
0 H
SAV
HANC
VANC
Digitized
Ancillary
Signals
of active video (SAV) and end of active video (EAV).
Ancillary data (ANC) and digitized ancillary signals are
permitted in regions not occupied by active video.
Figure 15.2 shows the raster diagram of Chapter 6,
augmented with EAV, SAV, and the HANC and VANC
regions. Details will be presented in Digital sync, TRS,
ancillary data, and interface, on page 389.
Composite digital SDTV (4fSC ) interface
Composite 4fSC digital interfaces code the entire 8- or
10-bit composite data stream, including sync edges,
back porch, and burst. The interface word rate is the
same as the sampling frequency, typically about half the
rate of a component interface having the same scanning
standard. The 4fSC interface shares the electrical
and physical characteristics of the 4:2:2 interface.
Composite 4fSC NTSC has exactly 910 sample intervals
per total line (STL ), and a data rate of about 143 Mb/s.
Composite 4f SC PAL has a noninteger number of sample
intervals per line: Samples in successive lines are offset
to the left a small fraction ( 4 ⁄ 625) of the horizontal
sample pitch. Sampling is not precisely orthogonal,
although digital acquisition, processing, and display
equipment treat it so. All but two lines in each frame
have 1135 S TL; each of the other two lines – preferably
lines 313 and 625 – has 1137 S TL. For 10-bit 4f SC, total
data rate (including blanking) is about 177 Mb/s.
CHAPTER 15 DIGITAL VIDEO INTERFACES 129