saa4996h NXP Semiconductors, saa4996h Datasheet - Page 15

• Manufacturer Part Number: saa4996h
• Description: Motion Adaptive Colour Plus And Control Ic Macpacic For Palplus
• Manufacturer: NXP Semiconductors

Philips Semiconductors
7.5
The functional block diagram of the MACPACIC for
PALplus is illustrated in Fig.1. The device consists of
4 main parts:
The clock rate of the input data is 16 MHz. Internally, the
device operates at a 32 MHz clock frequency. The clock
rate of the output data is either 32 MHz (in combination
with FM2, FM3 and VERIC) or 16 MHz for stand-alone
MACP processing.
The delay of the full PALplus module is 1.5 fields in the
PALplus and bypass mode. A field length measurement is
implemented. For MultiPIP with the help of a PIP module
the delay of the PALplus module is one line.
For stand-alone MACP the delay is one field, one line and
some clocks of processing delay.
For MultiPIP with the help of a PIP module the delay of
MACPACIC is two clocks (CLK_16).
7.6
7.6.1
To use a standard ADC with clamping on 16, a black
set-up for the CVBS signal and a black/mid grey set-up for
the helper signal has to be performed in the colour/helper
decoder. The shift values for black set-up and mid grey
set-up are inserted in line 22.
All values are nominal values.
CVBS:
Helper:
Y (standard input):
1996 Oct 28
Luminance and helper processing
Chrominance processing
Chrominance motion detection
Control.
clamp level: 16
black set-up: 51
white: 191
format: 8-bit, straight binary
mid grey set-up: 121
range: (121
format: 8-bit, offset binary
black: 16
peak white: 191
format: 8-bit, straight binary
Motion Adaptive Colour Plus And Control
IC (MACPACIC) for PALplus
Block diagram
Luminance and helper processing
I
NPUT RANGE
60) to (121 + 60) = 61 to 181
15
7.7
The luminance and the helper processing have two input
branches. One input is an 8-bit wide 16 MHz data stream
from the ADC. The other is an 8-bit wide 16 MHz data
stream from the field memory (FM1). The odd field of an
input frame is stored in the field memory FM1. In the even
field of a frame, the even field together with the delayed
odd field is processed by the MACPACIC.
To remove the chrominance part of the incoming
composite video signal, the Motion Adaptive Colour Plus
technique is applied. Colour Plus is a dedicated comb filter
technique, which makes full use of the correlation of two
successive fields.
During processing the data of the odd and even fields are
separated in a high-pass and low-pass part. The high-pass
part consists of the luminance high-pass component and
the modulated chrominance signal. Due to the phase
difference of the colour carrier of 180 from the odd to the
even field, the chrominance signal can be removed by
adding the high-pass signals.
This processing will work successfully in the film mode,
because scanned film material is motionless within the two
fields of one frame. In the camera mode a motion detector
fades down the luminance high-pass component if motion
is detected.
The following vertical low-pass filters perform a vertical
interpolation of the high-pass part by the factor of two.
In the event of bad signal conditions, the residual
cross-luminance signal, caused by clock jitter between two
fields, can be reduced by using this filter as a 2D comb
filter. Therefore different sets of coefficients can be
selected via SNERT.
The luminance high-pass part and the luminance low-pass
part are then added.
The automatic gain control (AGC) and automatic offset
control (AOC) functions use reference lines 23,
623 and 22 to reduce errors in the vertical reconstruction
in the VERIC. This is to reduce the effects of any errors
that might be caused due to variations in the conventional
PAL references in the signal during the transmission chain
with respect to the levels of the luminance letter box and
helper signals.
Luminance processing
Preliminary specification
SAA4996H