VPC 323xD, VPC 324xD
ADVANCE INFORMATION
Table 2–1 gives the picture settings achieving exact
level matching between the YCrCb_cip and
YCrCb_main channel.
The factor k is clamped to 0 or 64, hence selecting
YCrCb_main or the component input YCrCb_cip. (see
Table 2–2)
Table 2–1: Standard picture settings
2.4.4.2. Static Mixer Mode
input
format
contrast brightness satCr satCb
The signal YCrCb_main and the component signal
YCrCb_cip may also be statically mixed. In this envi-
ronment, k is manually controlled via I2C registers
FBGAIN and FBOFFS according to the following
expression:
RGB
27
27
68
68
29
40
23
40
YCrCb
k = FBGAIN*(31−FBOFFS) + 32
Note: R, G, B, Cr, Cb, = 0.7 Vpp, Y(+ sync) 1 Vpp
All the necessary limitation and rounding operation are
built-in to fit the range: 0 ≤ k ≤ 64.
2.4.4. Softmixer
In the static mixer mode as well as in the previously
mentioned static switch mode (see Table 2–2), the
softmixer operates independently of the analogue Fast
Blank input.
After an automatic delay matching, the component sig-
nals and the upsampled main video signal are gath-
ered onto a unique YCrCb channel by means of a ver-
satile 4:4:4 softmixer (see also Fig. 2–10).
The softmixer circuit consists of a Fast Blank (FB) pro-
cessing block supplying a mixing factor k (0...64) to a
high quality signal mixer achieving the output function:
2.4.4.3. Dynamic Mixer Mode
In the dynamic mixer mode, the mixer is controlled by
the Fast Blank signal. The VPC32xxD provides a linear
mixing coefficient
YCrCb_mix=( k*YCrCb_main+ (64-k)*YCrCb_cip )/64
The softmixer supports several basic modes that are
selected via I2C bus (see Table 2–2).
k=kl = FBGAIN*(FB−FBOFFS) + 32
(FB is the digitized Fast Blank), and a non-linear mix-
ing coefficient knl=F(kl), which results from a further
non-linear processing of kl.
2.4.4.1. Static Switch Mode
In its simplest and most common application the soft-
mixer is used as a static switch between YCrCb_main
and YCrCb_cip. This is for instance the adequate way
to handle a DVD component signal.
While the linear mixing coefficient is used to insert a
fullscreen video signal, the non-linear coefficient is
well-suited to insert Fast Blank related signals like text.
The non-linear mixing reduces disturbing effects like
over/undershoots at critical Fast Blank edges.
mixer
YCrCb_main
YCrCb_mix
VIDEO
Y/C processing
YCrCb_cip
Component
Processing
RGB/YCrCb
Fig. 2–10: Block diagram of the component mixer
14
Micronas
MICRONAS [ MICRONAS ]
