|
Parameters
|
525-line, 60 field/s
systems
|
625-line, 50 field/s
systems
|
|
1. Coded
signals: Y, CR, CB
|
These
signals are obtained from gamma pre-corrected signals
|
|
2. Number
of samples per total line:
– luminance
signal (Y)
– each colour-difference signal
(CR,
CB)
|
858
429
|
864
432
|
|
3.
Sampling structure
|
Orthogonal, line, field and frame repetitive. CR and
CB samples
co-sited with odd (1st, 3rd, 5th, etc.) Y
samples in each line
|
|
4. Sampling
frequency:
– luminance signal
– each colour-difference signal
|
13.5 MHz
6.75
MHz
The tolerance for the sampling frequencies
should coincide with the tolerance for the line frequency of the
relevant colour television standard
|
|
5.
Form of coding
|
Uniformly quantized PCM, 8 (optionally 10) bits
per sample, for the luminance signal and each colour-difference signal
|
|
6. Number
of samples per digital active line:
– luminance signal
– each colour-difference signal
|
720
360
|
|
7. Analogue-to-digital
horizontal timing relationship:
– from end of digital active line
to OH
|
16 luminance clock periods
|
12 luminance clock periods
|
|
8. Correspondence
between video signal levels and quantization levels:
– scale
– luminance signal
– each colour-difference signal
|
(Values
are decimal)
0 to 255
220 quantization levels with the black level
corresponding to level 16 and the peak white level corresponding to
level 235. The signal level may occasionally excurse beyond level 235
225 quantization levels in the centre part of
the quantization scale with zero signal corresponding to level 128
|
|
9.
Code-word usage
|
Code words corresponding to quantization levels
0 and 255 are used exclusively for synchronization. Levels 1 to 254 are
available for video
|
