saa4977h NXP Semiconductors, saa4977h Datasheet - Page 9

• Manufacturer Part Number: saa4977h
• Description: Video Processing
• Manufacturer: NXP Semiconductors

Philips Semiconductors
7.2.5
For displaying 4 : 3 sources on 16 : 9 screens a horizontal
signal compression can be done by data interpolation.
Therefore two horizontal compression factors of either
4
be switched on or off and the compression mode 16 : 9 or
14 : 9 can be selected. When the compression mode is
active, a reduced number of the interpolated data is stored
in the field memory. To achieve sufficiently high accuracy
in interpolation Variable Phase Delay filters are used
(VPD10 for luminance, a multiplexed VPD06 for UV).
7.3
7.3.1
An up-converter to 4 : 2 : 2 is applied with a linear
interpolation filter for creation of the extra samples. These
are combined with the original samples from the 4 : 1 : 1
stream.
7.3.2
The Digital Colour Transient Improvement (DCTI) is
intended for U and V signals originating from a 4 : 1 : 1
source. Horizontal transients are detected and enhanced
without overshoots by differentiating, make absolute and
again differentiating the U and V signals separately.
This results in a 4 : 4 : 4 U and V bandwidth. To prevent
third harmonic distortion, typical for this processing, a so
called over the hill protection prevents peak signals
becoming distorted. Via the I
control: gain width (see Fig.4), threshold (i.e. immunity
against noise), selection of simple or improved first
differentiating filter (see Fig.3), limit for pixel shift range
(see Fig.5), common or separate processing of U and V
signals, hill protection mode (i.e. no discolourations in
narrow colour gaps), low-pass filtering for U and V signals
(see Fig.6) and a so called super hill mode, which avoids
discolourations in transients within a colour component.
7.3.3
A linear peaking is applied, which amplifies the luminance
signal in the middle and the upper ranges of the
bandwidth.
The filtering is an addition of:
2000 May 25
3
The original signal
The original signal high-passed with maximum gain at
frequency =
The original signal band-passed with centre
frequency =
Besic
or
7
6
Digital processing at 2f
are possible. Via the I
H
4 : 1 : 1
DCTI
Y-
ORIZONTAL COMPRESSION
PEAKING
1
1
2
4
f
f
TO
s
s
(8 MHz)
(4 MHz)
4 : 2 : 2
UP
2
2
C-bus it is possible to
C-bus the compression can
-
CONVERSION
H
level
9
The band-passed and high-passed signals are weighted
with factors 0,
in a maximum gain difference of 2 dB at the centre
frequencies.
Coring is added to obtain no gain for low amplitudes in the
high-pass and band-pass filtered signal, which is
considered to be noise. Coring levels can be programmed
as 0 (off), 8, 16, 24 to 120 LSB w.r.t. the (signed)
11-bit filtered signal.
In addition the peaking gain can be reduced depending on
the signal amplitude, programming range 0 (no
attenuation),
larger undershoots than overshoots, programming range 0
(no attenuation of undershoots),
7.3.4
The Y samples can be shifted onto 8 positions w.r.t. the
UV samples. This shift is meant to account for a possible
difference in delay previous to the SAA4977H. The zero
delay setting is suitable for the nominal case of aligned
input data. The other settings provide one to seven
samples less delay in Y.
7.3.5
Sidepanels are generated by switching Y and the 4 MSBs
of U and V to certain programmable values. The start and
stop values for the sidepanels w.r.t. the rising edge of the
HRD signal are programmable in a resolution of 4 LLD
clock cycles. In addition, a fine shift of 0 to 3 LLD clock
cycles of both values can be achieved.
Blanking is done by switching Y to value 64 at 10-bit word
and UV to value 0 (in 2’s complement). Blanking is
controlled by a composite signal HVBDA, consisting of a
horizontal part HBDA and a vertical part VBDA. Set and
reset value of the horizontal control signal HBDA are
programmable w.r.t. the rising edge of the HRD signal, set
and reset value of the vertical control signal VBDA are
programmable w.r.t. the rising edge of the VA signal.
The range of the Y output signal can be selected between
9 and 10 bits. In the case of 9 bits for the nominal signal
there is room left for undershoot and overshoot (adding up
to a total of 10 bits). In the case of selecting all 10 bits of
the luminance DAC for the nominal signal any under or
overshoot will be clipped (see Fig.11).
The original signal band-passed with centre frequency
of 2.38 MHz.
Y-
S
IDEPANELS AND BLANKING
DELAY
1
1
4
16
,
2
,
4
2
, and
16
,
3
16
4
,
4
. It is also possible to make
4
16
,
5
1
16
Preliminary specification
4
,
,
6
2
16
4
SAA4977H
, and
, and
4
8
4
16
.
, resulting