saa7134hl NXP Semiconductors, saa7134hl Datasheet - Page 24

• Manufacturer Part Number: saa7134hl
• Description: Pci Audio And Video Broadcast Decoder
• Manufacturer: NXP Semiconductors

Philips Semiconductors
SAA7134HL_4
Product data sheet
6.6.1 Analog video inputs
6.6.2 Video synchronization and line-locked clock
6.6.3 Video decoding and automatic standard detection
6.6.4 Adaptive comb filter
6.6 Video processing
The SAA7134HL provides five analog video input pins:
Analog anti-alias filters are integrated on chip and therefore, no external filters are
required. The device also contains automatic clamp and gain control for the video input
signals, to ensure optimum utilization of the ADC conversion range. The nominal video
signal amplitude is 1 V (p-p) and the gain control can adapt deviating signal levels in the
range of +3 dB to 6 dB. The video inputs are digitized by two ADCs of 9-bit resolution,
with a sampling rate of nominal 27 MHz (the line-locked clock) for analog video signals.
The SAA7134HL recovers horizontal and vertical synchronization signals from the
selected video input signal, even under extremely adverse conditions and signal
distortions. Such distortions are ‘noise’, static or dynamic echoes from broadcast over air,
crosstalk from neighboring channels or power lines (hum), cable reflections, time base
errors from video tape play-back and non-standard signal levels from consumer type
video equipment (e.g. cameras, DVD).
The heart of this TV synchronization system is the generation of the Line-Locked Clock
(LLC) of nominal 27 MHz, as defined by ITU-R BT.601 . The LLC ensures orthogonal
sampling, and always provides a regular pattern of synchronization signals, that is a fixed
and well defined number of clock pulses per line. This is important for further video
processing devices connected to the peripheral video port (pins GPIO). It is very effective
to run under the LLC of 27 MHz, especially for on-board hardware MPEG encoding
devices, since MPEG is defined on this clock and sampling frequency.
The SAA7134HL incorporates color decoding for any analog TV signal. All color
TV standards and flavors of NTSC, PAL, SECAM and non-standard signals (VCR) are
automatically recognized and decoded into luminance and chrominance components, i.e.
Y-C
The video decoder of the SAA7134HL incorporates an automatic standard detection, that
does not only distinguish between 50 Hz and 60 Hz systems, but also determines the
color standard of the video input signal. Various preferences (‘look first’) for automatic
standard detection can be chosen, or a selected standard can be forced directly.
The SAA7134HL applies adaptive comb filter techniques to improve the separation of
luminance and chrominance components in comparison to the separation by a chroma
notch filter, as used in traditional TV color decoder technology. The comb filter compares
the signals of neighboring lines, taking into account the phase shift of the chroma
subcarrier from line to line. For NTSC the signal from three adjacent lines are investigated,
and in the event of PAL the comb filter taps are spread over four lines.
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•
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B
Composite video signals (CVBS), from tuner or external source
S-video signals (pairs of Y-C), e.g. from camcorder
DTV/DVB ‘low-IF’ signal, from an appropriate DTV or combi-tuner
-C
R
, also known as YUV.
Rev. 04 — 31 March 2006
PCI audio and video broadcast decoder
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
SAA7134HL
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