Philips FM24 Service Manual page 99

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Digital Video
This part describes the digital video path on the SCAVIO panel,
starting at the AD converters in either the AD9887 (item 7170)
or in the SAA7118E (item 7225) and ending at the output for the
PDP.
For both the Basic as the Enhanced version, everything 'after'
the PixelWorks chip, is equal.
For the Basic version, the input for the PixelWorks only
consists of the 'Graphics path'.
For the Enhanced version, it is both the 'Graphics path' as the
'Video path'.
The SCAVIO panel contains the following functions in the video
path:
1. The 'YPbPr to RGB matrix' and '2fH Video+Sync Switch'
are explained above in the 'Analogue Video' part.
2. The 'Digital Video' path containing the Digital Video
Decoder and the De-interlacer.
3. The 'Digital Graphics' path containing the ADC+TMDS
decoder.
4. The 'Scaler' which is the PixelWorks (PW164-10R) plus
Memory.
5. The 'EPLD' for sync decoding and video manipulation.
6. The 'LVDS' encoder.
The Digital 'Graphics Path'
This is a straightforward application of the Analogue Devices
AD9887 (item 7170). Inputs for this device are:
• FTV Receiver box,
• VGA formats (up to SXGA@75 Hz),
• 2fH RGB+HV (only in Enhanced version),
• 2fH YPbPr, which is converted to RGB by the 'YUV to RGB'
matrix (only in Enhanced version),
• DVI-d (only in Enhanced version).
Analogue input:
The AD9887 is meant to sample 'pixel synchronous'. To
achieve this, a (software) driver is running on the PixelWorks
processor (PW). After hooking up a source to the AD9887, the
PW starts counting the number of lines per field and calculates
the H-period time. With these two values, it determines the
exact match or the closest match out of a look-up-table (LUT)
with VGA standards. When the correct standard is determined,
the PW will set the AD9887 I
The AD9887 should now sample with exact the same
frequency as the incoming standard requires. This is done to
get an optimal picture performance.
It also is a 'must' when a computer graphics card is connected,
because there is no, or very little, post anti-aliasing filtering
done on such cards. Therefore, the outputted RGB samples
need to be exactly aligned with the sampling of the AD
converter.
Analogue input signals can go up to SXGA@75 Hz, which
gives a pixel clock of 135 MHz. In fact, it can handle any
standard with a pixel rate up to 140 MHz.
Special modes are made for the F21R E-box, for both PAL and
NTSC. These are invoked when an E-box is connected to the
SCAVIO panel.
Digital input:
Via the DVI connector (Enhanced version only) it is possible to
insert TMDS (Transition Minimised Differential Signalling) data
into the SCAVIO panel. DVI is a fairly new computer graphics
standard, which can be seen as the digital follow-up of the
analogue VGA interface. The TMDS signal is directly fed into
the AD9887, where any DVI standard up to SXGA@60 Hz can
be decoded to RGBHV.
The preferred VGA standard for the FM24 is programmed in
the DDC EEPROM (item 7215), which can be read by the PC.
Via an internal switch, it is possible to choose between the
analogue input and the digital input. The output format is for
both inputs the same (8 bit RGB plus HV). The driver
determines whether the AD9887 outputs single or dual pixels.
For lower standards like VGA@60Hz, the interface will be
single pixel, which means that every clock cycle one byte of R,
Circuit Descriptions and List of Abbreviations
2
C registers to the correct value.
Digitized in Heiloo, Holland
FM24
G, and B data is outputted. Dual pixel means that on every
clock cycle two bytes of R, G, and B data outputted. These two
bytes are de-multiplexed, which is done to make the interface
more robust for jitter, set-up, and hold times, and to reduce the
digital data rate over the PCB (reduced EMC).
Digital 'Video Path'
This path is only available in the Enhanced version of the
SCAVIO panel and is used for the following input signals:
• CVBS input,
• Y/C input, and
• 1fH YPbPr.
It is a straightforward application of the Philips SAA7118 (item
7225) and the Micronas SDA9400 (item 7280).
The SAA7118 is a PAL/NTSC/SECAM Digital Video Decoder
with adaptive digital comb filter and component video input. It
decodes all input standards to 4:2:2 YCbCr, which then is
processed by the SDA9400.
The SDA9400 is a motion adaptive de-interlacer, which makes
a progressive video signal from the interlaced input.
Depending on the motion in the picture, it will just interleave the
odd and even field (no motion: ABAB) or repeats the same field
twice; this is also known as line doubling (motion: AABB). The
motion detection is pixel based, with a soft-switch between
'motion' and 'no motion'.
After the de-interlacer, the signal is fed as a 4:2:2 YCbCr
progressive scan signal to the video port of the PixelWorks
processor.
The PixelWorks PW164 Scaler
The PixelWorks PW164 Image Processor is a highly integrated
(Ball Grid Array, BGA) chip, which interfaces video inputs and
computer graphics in virtually any format to the PDP.
Computer images from VGA to UXGA resolution input to the
chip can be resized to fit on the PDP. Horizontal and vertical
image scalers, coupled with intelligent frame locking circuitry
create sharp images, centred on the screen and without user
intervention. An embedded DRAM frame buffer and memory
controller perform the frame rate conversion.
Video data from 4:3 aspect ratio NTSC or PAL and 16:9 aspect
ratio sources such as HDTV and DVD are supported. Non-
linear scaling (only with Receiver Box) and separate horizontal
and vertical scalers allow these inputs to be resized optimally
for the native resolution of the PDP.
For more information, see http://www.pixelworksinc.com/
index.phtml
31/8/2014
9. EN 99