VCOMP
Non-Constrained HD Main
Video Input
CSC
3-Tap Vertical
and Horizontal
Decimator
2x Vertical and
Horizontal
Interpolator
Interlacer
CIG_en
0
1
Delay
Interlacer
Interlacer
CIG
Non-Constrained HD Main
Video Output to
DVO1/HDCOMP
Constrained HD Main
Video Output to
DVO2
PIP Video
Output to
DVO1/DVO2/HDCOMP
CIG_en
0
1
PIP Video Input
Internal Modules
80
SPRUHI7A – December 2012 – Revised June 2016
Copyright © 2012–2016, Texas Instruments Incorporated
High-Definition Video Processing Subsystem (HDVPSS)
Figure 1-36. CIG Block Diagram
1.2.4.2.1 Constrained Video Mode
When the image constraining is required, the CIG requires the incoming unconstrained video to be in
progressive scan format in order to apply vertical decimation filter properly. If the output is required to be
in interlaced format, the CIG can optionally interlace the outgoing video on both outputs. The PIP video
output format (interlaced or progressive) should match the main video output format if it is used as a PIP
over the main video.
For the non-constrained video, the output is simply a delayed version (same delay as that of constrained
video) of the original video. For the constrained video, ½ decimation filters (3-tap) and 2x interpolation
filters (2-tap average) are used to first reduce the overall source resolution by ¼ (½ in vertical ½ in
horizontal direction) and to later recover the original display size.
The CIG module performs ½ decimation in both vertical and horizontal directions to achieve the resolution
reduction by ¼th (½ in vertical ½ in horizontal direction) on the constrained output and 2x interpolation to
restore the total pixel counts. To minimize further filtering of previously optimized image data, a simple 3-
taps half-band-filter (¼, ½, ¼) is used for both vertical and horizontal decimation filters while a simple
average filter is used for interpolation.
1.2.4.2.2 Interlacer
The CIG module supports interlacing on each output to generate an interlaced output from the progressive
input if needed. The interlacing is performed simply by sending only the current field lines and discarding
the others. The current field id is passed on from the upstream module (CSC for HD main video and CSC
for PIP video).
1.2.4.2.3 Alpha assignment for Chroma Keying (Transparency) and Blending
The CIG module receives RGB data and assigns an alpha value to each pixel data based on
programmable transparency and blending configurations. When enabled, the blender block in the COMP
module uses the configured 8-bit alpha value for both HD main and PIP video windows. Also, it will force a
pixel’s alpha value to be 0 if the transparency mode is enabled and pixel’s color is same as the user-
configured transparency color value. A bit masking feature is provided to ignore bottom 1-3 bits when
making comparison for transparency color value. The blending alpha value configured in CIG module is
carried onto COMP module.