CX25870/871
1.0 Functional Description
Flicker-Free Video Encoder with Ultrascale Technology
1.3 Device Description
The advantage of this type of video is increased image quality combined with
more lifelike colors and crisper detail. Because the video information is
transferred over three separate connecting cables instead of two (for S-Video) or
one (for Coaxial or RCA/Composite), 480i Component Video yields the best
standard definition TV quality available. However, because we are still dealing
with standard 480 line interlaced resolutions, this format remains inferior to
High-Definition TV.
Output devices used for generating this format include, but are not limited to,
Digital TV set top boxes, Satellite DBS Receiver Decoders, and DVD players.
Input media capable of decoding ColorStream include television receivers and/or
monitors.
While in the Component Video mode, all 10-bits of the CX25870’s D/A
converters are available for encoding. This results in a D/A conversion more
accurate than conventional 8-bit, 13.500 MHz systems. The end result is a more
artifact-free and clear image.
Some major characteristics governing the interlaced standard definition
television analog component video interface are as follows:
Output
Scanning
Format
Pixels per
Active Line
Active Lines
per Frame
Frame Rate
(Hz)
Total Samples
per Line
Total Liens per
Frame
720
480
30 / 1.001
Interlaced
858
525
•
The digital input stream can be received in a progressive (i.e.,
noninterlaced) format or interlaced format. Interlaced data must be
transmitted as ODD–EVEN–ODD … fields. The fields carry every other
scan line in succession with succeeding fields carrying the lines not
scanned by the previous field.
•
•
Each field will be divided into an active picture area and a vertical
blanking interval (VBI). Similarly, each line will be divided into an active
pixel area and a horizontal blanking interval.
The 480i video output will be capable of either a 4:3 or 16:9 aspect ratio
through embedding of Wide Screen Signaling (WSS) bits into the
appropriate lines in the VBI. Review the section 1.3.35 in the data sheet for
more details.
If configured properly, the CX25870’s EIA 770.2-A compliant Component
Video luminance signal has a peak amplitude of 700 mV from the blanking level,
with zero setup. A negative-going bilevel sync pulse of 300 mV, conforming to
the timing requirements in Figure 1.3-a, is added to the Luma signal as the only
timing reference for the complete Y PR PB set of signals.
Neither PR nor PB will contain an embedded sync pulse. Both will have a
maximum peak amplitude of 350 mV. The DC level of PR and PB during the
horizontal line shown in Figure 1-36 below will be at reference black with a
voltage of 0 V. It will be generated in conformance with the EIA 770.2-A and
EIA770.1 standards. The only differences between these standards are the
presence of the 7.5 IRE setup pedestal and slightly different luminance levels.
Check Tables 1-27 and 1-28 for complete programming instructions for either
standard.
100381B
Conexant
1-81
CONEXANT [ CONEXANT SYSTEMS, INC ]
