SDA9401 Datasheet, PDF (16/69 Pages) List of Unclassifed Manufacturers – Scan Rate Converter using Embedded DRAM Technology Units

SDA 9401
6.3 Low data rate processing
The next figure shows the block diagram of the low data rate processing block. The input signal can
be vertically and horizontally compressed by a limited number of factors. In case of multipicture
mode the internal Multipicture controller will use both compression blocks to control the different
modes. Furthermore the input signal can be processed by different noise reduction algorithms to
reduce the noise in the signal. The noise measurement block determines the noise level of the input
signal.
Block diagram of low data rate processing
NMLINE, NMALG NOISEME
MULTIPIC, PICPOS, YBORDER,
UBORDER, VBORDER
Noise
measurement
Multipicture
controller
YIN
UVIN
Line
memories
Vertical
compression
Horizontal
compression
VDECON,
VCSNRON
HDECON,
HCSNRON
Spatial noise
reduction
Temporal
noise
reduction
SNRON
NRON
Y from Memory
Y to Memory
UV to Memory
UV from Memory
The different blocks and the corresponding parameters will be described now in more detail.
6.3.1 Vertical compression
The vertical compression compresses the incoming signal vertically by a constant factor given by
the parameter VDECON. For the Y and UV signal different filter characteristics are used. The
vertical compression can be switched off. For the multipicture modes the factors VDECON 2, 3 and
4 are necessary. Different filter characteristics are used for the factors 3 and 4. High quality vertical
compression for double window applications is possible, because the filter characteristic is
optimized for the factor 1.5.
The table below shows the relation between the parameter VDECON and the compression factor.
Input write parameter: VDECON
VDECON (1Ch)
0
1
2
3
4
5
6
7
Vertical compression off
Factor 1.25
Factor 1.5
Factor 1.75
Factor 2.0
Factor 3.0
Factor 4.0
not defined
Inside the SDA 9401 the number of active lines per field depends on the chosen vertical
compression factor VDECON (see also chapter Output sync controller (OSC) on page 29).
Micronas
16
Preliminary Data Sheet