DigitalVideoAndHDTVAlgorithmsAndInterfaces.pdf

8-bit code
200
176.25
70.5
60
4
757 + S PW
67 + Sample clocks, 14.3181 _ 8 _ 768 SAL 0H 1 MHz
910 S TL
Figure 42.2 4f SC NTSC digital waveform with setup. The excursion indicated reflects the range of
the luma component; the chroma component will cause excursions outside this range. It was
a problem in 8-bit 4f SC systems that the setup level had an inexact representation.
SMPTE 170M, Composite Analog
Video Signal – NTSC for Studio
Applications.
784 33 ⁄90. Burst samples lie at the -33°, 57°, 123°, and
213° phases of burst, and take 8-bit values {46, 83, 74,
37}. Although 4f SC NTSC is sampled on the IQ axes,
narrowband Q filtering is not necessarily applied.
Each line has 910 S TL and 768 S AL . Samples are
numbered from 0 relative to the leftmost active sample.
The 50%-point of analog sync falls 57 ⁄90 of the way
between two samples. With conventional sample
numbering, where sample 0 is the leftmost active
sample in a line, 0 H falls between samples 784 and 785.
The first word of TRS-ID is at sample 790.
The electrical and mechanical interface for 4f SC is
derived from the Rec. 656 parallel and serial interfaces;
see SDI coding, on page 396.
Composite analog NTSC interface
Figure 42.3 above shows a waveform drawing of luma
at a 480i composite analog interface, with 7.5% setup;
the levels are detailed in Composite analog levels, on
page 407. The excursion of 480i luma – from synctip to
reference white – is normally 1 VPP. Including
CHAPTER 42 480 i NTSC COMPOSITE VIDEO 517