SAA7134 Philips Semiconductors, SAA7134 Datasheet - Page 27

• Manufacturer Part Number: SAA7134
• Description: PCI audio and video broadcast decoder
• Manufacturer: Philips Semiconductors

Philips Semiconductors
7.6
7.6.1
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.
7.6.2
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
neighbouring 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.
7.6.3
The SAA7134HL incorporates colour decoding for any
analog TV signal. All colour TV standards and flavours of
NTSC, PAL, SECAM and non-standard signals (VCR) are
automatically recognized and decoded into luminance and
chrominance components, i.e. Y-C
YUV.
2002 Dec 17
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.
PCI audio and video broadcast decoder
Video processing
A
V
V
DETECTION
NALOG VIDEO INPUTS
IDEO SYNCHRONIZATION AND LINE
IDEO DECODING AND AUTOMATIC STANDARD
B
-C
R
, also known as
-
LOCKED CLOCK
27
The video decoder of the SAA7134HL incorporates an
automatic standard detection, that does not only
distinguish between 50 and 60 Hz systems, but also
determines the colour 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.
7.6.4
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 colour decoder
technology. The comb filter compares the signals of
neighbouring 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.
Comb filtering achieves higher luminance bandwidth,
resulting in sharper picture and detailed resolution. Comb
filtering further minimizes colour crosstalk artifacts, which
would otherwise produce erroneous colours on detailed
luminance structures.
The comb filter as implemented in the SAA7134HL is
adaptive in two ways:
The integrated digital delay lines are always exactly
correct, due to the applied unique line-locked sampling
scheme (LLC). Therefore the comb filter does not need to
be switched off for non-standard signals and remains
operating continuously.
7.6.5
The SAA7134HL detects if the decoded video signal is
copy protected by the Macrovision system. The detection
logic distinguishes the three levels of the copy protection
as defined in rev. 7.01, and are reported as status
information. The decoded video stream is not effected
directly, but application software and Operation System
(OS) has to ensure, that this video stream maintains
tagged as ‘copy protected’, and such video signal would
leave the system only with the reinforced copy protection.
The multi-level Macrovision detection on the video capture
side supports proper TV re-encoding on the output point,
e.g. by Philips TV encoders SAA712x or SAA7102.
Adaptive to transitions in the picture content
Adaptive to non-standard signals (e.g. VCR).
A
M
DAPTIVE COMB FILTER
ACROVISION DETECTION
SAA7134HL
Product specification