Instruction manual

HDE-3000 - 63 -
UYC File Positioning Parameters for PAL
For PAL, the TV screen is 720 pixels wide by 625 lines, but 42 lines are used for the
VBI (vertical blanking interval), and two lines (line 22 of each field) are used for closed
captioning. The HDE-3000 can only overlay 512 lines (because it only has 512 lines of
video memory), so the HDE-3000 can overlay lines 40 to 255 in each filed. So the total
number of lines the HDE-3000 can overlay is 512.
The xPosition parameter is the same for PAL as for NTSC.
The yPosition parameter valid values for PAL are from 40 to 295. A value of 40 will
place the top edge of the uyc file as close to the top edge of the TV screen as possible.
A value of 166 will place the top edge of the uyc file in the middle of the TV screen.
Full Frame UYC files for PAL
For PAL, the full frame uyc file size is 720 X 512. When full frame uyc files are used,
the xPosition parameter should always be 0 and the yPosition parameter should always
be 40.
Converting Graphics Files to UYC Files
Before a graphics file can be overlaid onto video by the HDE-3000, the file must be
converted to a uyc file. The HDE-3000 cannot directly overlay other graphics files such
as bmp or gif. LINK provides a number of converter utilities to convert other graphics
files to uyc files. The following is a list of the available converter utilities:
From converter name
BMP BMP2UYC
PCX PCX2UYC
TIF TIF2UYC
PNG PNG2UYC
Note that there is a problem with most graphics files: they do not contain
transparency (alpha) information. The only graphics files that do contain alpha
information are 32 bit BMP (RGB-alpha), and PNG.
To solve this problem, we have added a capability to our TIF and BMP converter
utilities to define a “transparent color”. When a uyc file is created by the utilities, every
pixel that is the “transparent color” is assigned an alpha value of 0 (transparent), and
every pixel that is not the “transparent color” is assigned an alpha value of 255 (opaque).
The next challenge is defining the “transparent color”. You can choose an RGB color
value as the “transparent color”, or if your files use a color palette then you can define a
color index as the “transparent color index” (for example, the first color in the palette).
Unfortunately, no two HDE-3000 users agree on the definition of the “transparent color”,
so LINK offers to customize the converter utilities for each user.