pnx1700 NXP Semiconductors, pnx1700 Datasheet - Page 367

• Manufacturer Part Number: pnx1700
• Description: Connected Media Processor
• Manufacturer: NXP Semiconductors

Philips Semiconductors
Volume 1 of 1
PNX17XX_SER_1
Preliminary data sheet
Figure 3:
Undithering and Pedestal Manipulation
range for 9+1
range for 8bits
nominal data
nominal data
format
nominal data
range for 10
For true 10bits input, pedestal substraction is recommended off, the different nominal ranges for various layers
bits input
bits input
format
10 bits input
8 bits input
input
alpha (2 bit)
u/m/l (8 bit)
288~726
64~940
16~235
10bu
8bu
The UDTH unit, however, does more than just undithering. It does format conversion
as well. QVCP has its own data format protocol (10-bit signed data -- UP(Y/R), MI(U/
G), LO(V/B) --- and 8-bit unsigned alpha) and is designed to process data with a
nominal range of 9 bits; one extra bit is reserved for overshoots and undershoots.
Input data gets converted, from an external format to the native QVCP format, inside
the UDTH module.
figure, the nominal data range is shown for each conversion step for both 8- (bottom
part) and 10- (top part) bit inputs. Note that an 8-bit input to QVCP will be converted
to a 9+1 format by undithering or by left shifting. A 10-bit input, however, can be either
true 10 bits or 9+1 bits; for the former, there is not too much head-room left and so,
the nominal range of the various layers should be equalized at the VCBM unit.
The function of Alpha Processing unit is to insert a fixed alpha or pre-multiply each
pixel with a per-pixel alpha. For a 10-bit input, only fixed alpha is supported.
8bs
Unsigned to
conversion
signed
-112~107
-448~428
-224~214
Increasing nominal range by 2
10bs
8bs
could be equalized at the VCBM unit.
2LSB
Left shift by 1 add 0 to
increasing
Append 2nd MBS to
Nominal
Rev. 1 — 17 March 2006
range
8MSB
Figure 3
by 2
LSB position
LSB position
Undither
or
or
-224~214
10bit data from
9bs
u/m/l path and
Reconstruct
alpha path
of the MSB
shows the data-flow diagram of the UDTH unit. In the
extension
Sign
bit
-224~214
-448~428
-224~214
10bs
10bs
processing
Alpha
9bs
if pedestal substraction is on
if pedestal substraction is on
if pedestal substraction is on
removing
Pedestal
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
-512~364
-448~428
-256~182
-224~214
PNX17xx Series
-256~182
-224~214
else
else
10bs
else
10bs
~511
-512
clip
Chapter 11: QVCP
11-10