Internal Modules
88
SPRUHI7A – December 2012 – Revised June 2016
Copyright © 2012–2016, Texas Instruments Incorporated
High-Definition Video Processing Subsystem (HDVPSS)
1.2.5.2.2.1.6 Boundary Box Blending
Even with anti-flickering, the flicker around the top and bottom edges of a region may still exists when the
anti-flickered region is composed onto the output display in the COMP module. The GRPX supports
overwriting alpha values of pixels that make up a 1-pixel wide boundary box of a region with a semi-
transparent (alpha) value (default – 0x80) so that the flickering around the edges can be minimized. This
feature is enabled when bound_box_en is set to `1`. The alpha value for the boundary box is
programmable in the bit-field bb_alpha.
1.2.5.2.3 Blending/Transparency Handling
The GRPX supports four blending modes (no-blending, global, pixel/CLUT, pixel) and a transparency
mode for each region to determine how alpha value for each pixel is set. The configuration for blending
and transparency are in the region attributes and are shown again in
Table 1-20. Blending and Transparency Configuration
Attribute
Bits
Description
Disp_blend_cfg
[97:88]
Blending configuration
[95:88]: Blending (alpha) value
[97:96]: Blending type
0 = No Blending
1 = Region global blending
2 = Color (palette) blending
3 = Pixel (embedded alpha) blending
disp_trans_cfg
[127:101]
Transparency (color keying enable) configuration bits
[103:102]: Transparency LSB bit masking
00 = No masking
01 = Mask[0] during pixel data comparison to TRANS_COLOR
10 = Mask[1:0]
11 = Mask[2:0]
Example: If TR_LSB_MASK is set to 2'b11, top 5 bits of R/G/B
component data are compared to the corresponding 5 bits of
TRANS_COLOR R/G/B color.
[101]: Transparency enable
0 = Disable
1 = Enable transparency for video layer
[127:104]: Transparency color (RGB24)
When no-blending is selected, the GRPX forces each alpha to FFh to make the region total opaque. In
region global-blending, a programmed alpha value in bits [95:88] (also called as “global blend” value) is
assigned to each pixel similar to the no-blending case.
For color or pixel blending, the VPDMA sets the alpha value with CLUT mapping or with embedded Alpha
value (argb format source) respectively. In these two modes, the GRPX simply passes the alpha value
from the VPDMA to COMP module. Pixel level blending is performed in the COMP module for both color
and pixel blending modes.
When transparency is enabled, each pixel color is compared against the transparency color to determine
whether the pixel is to be transparent or not. If the colors match, the alpha value is forced to 00h.
Otherwise, the alpha value remains as programmed.
The blending level supported is from 0 (transparent) to 255 (totally opaque).
Because the alpha value is also scaled in the same way the color components (RGB) are scaled, all
enabled blending/transparency related tasks are performed in the following order:
1. Application of No-blending (force alpha = FFh) or Global-blending (force alpha=programmed global
blend level)
2. Transparency check to force alpha = 0 for transparent pixels
3. Stenciling application to force masked pixels (stencil data = 1) with alpha = 0
4. Scaling of Alpha (if scaling enabled)
5. Box Blending (force alpha = programmed box_blend_level)
