ADVANCE INFORMATION
VDP 313xY
2.5. Horizontal Scaler
2.6. Blackline Detector
The 4:2:2 YCRCB signal from the color decoder is pro-
cessed by the horizontal scaler. The scaler block
allows a linear or nonlinear horizontal scaling of the
input video signal in the range of 0.25 to 4. Nonlinear
scaling, also called panorama vision, provides a geo-
metrical distortion of the input picture. It is used to fit a
picture with 4:3 format on a 16:9 screen by stretching
the picture geometry at the borders. Also, the inverse
effect can be produced by the scaler. A summary of
scaler modes is given in Table 2–1.
In case of a letterbox format input video, e.g. Cinemas-
cope, PAL+ etc., black areas at the upper and lower
part of the picture are visible. It is suitable to remove or
reduce these areas by a vertical zoom and/or shift
operation.
The VDP 313xY supports this feature by a letterbox
detector. The circuitry detects black video lines by
measuring the signal amplitude during active video.
For every field the number of black lines at the upper
and lower part of the picture are measured, compared
to the previous measurement and the minima are
stored in the I2C-register BLKLIN. To adjust the picture
amplitude, the external controller reads this register,
calculates the vertical scaling coefficient and transfers
the new settings, e.g. vertical sawtooth parameters,
horizontal scaling coefficient etc., to the VDP 313xY.
The scaler contains a programmable decimation filter,
a 1-line FIFO memory, and a programmable interpola-
tion filter. The scaler input filter is also used for pixel
skew correction (see Section 2.4.10. on page 12). The
decimator/interpolator structure allows optimal use of
the FIFO memory. The controlling of the scaler is done
by the internal Fast Processor.
Letterbox signals containing logos on the left or right
side of the black areas are processed as black lines,
while subtitles, inserted in the black areas, are pro-
cessed as non-black lines. Therefore the subtitles are
visible on the screen. To suppress the subtitles, the
vertical zoom coefficient is calculated by selecting the
larger number of black lines only. Dark video scenes
with a low contrast level compared to the letterbox area
are indicated by the BLKPIC bit.
Table 2–1: Scaler modes
2.7. Test Pattern Generator
Mode
Scale
Factor
Description
The YCRCB outputs can be switched to a test mode
where YCRCB data are generated digitally in the
VDP 313xY. Test patterns include luminance/chromi-
nance ramps and flat fields.
Compression 0.75
4:3 → 16:9
4:3 source displayed on
a 16:9 tube,
linear
with side panels
Panorama
4:3 →16:9
non-
linear
compr
4:3 source displayed on
a 16:9 tube,
Borders distorted
Zoom
4:3 → 4:3
1.33
linear
Letterbox source (PAL+)
displayed on a 4:3 tube,
vertical overscan with
cropping of side panels
Panorama
4:3 → 4:3
non-
linear
zoom
Letterbox source (PAL+)
displayed on a 4:3 tube,
vertical overscan, bor-
ders distorted, no crop-
ping
Micronas
13
MICRONAS [ MICRONAS ]
