2.0 Inputs and Timing
2.2 Digital Video Ports
Bt860/861
Multiport YCrCb to NTSC/PAL /SECAM
2.2 Digital Video Ports
Internally, data to the Bt860/861 is treated as either video, overlay, or alpha data.
Video data is the primary visual program content, while overlay data is used for
informational or navigational content displayed over the visual program. Alpha
data controls the pixel blending of the video and overlay content. Sufficient
flexibility exists in the Bt860/861 to allow for a variety of source and blending
configurations and interesting visual effects.
Video data is supplied by either the P (Primary Video) port, or the VID
(Secondary Video) port. Overlay data can be supplied by either the P port or the
OSD (On Screen Display) port. Alpha data can be supplied by the ALPHA port,
or embedded in the two LSBs of the overlay luminance data. Figure 2-1
illustrates the pixel latching and blending mechanism.
Figure 2-1. Pixel Latching and Blending Mechanism
2
2
8
8
Blend
Detection
ALPHA
OSD
P
4
2
8
Overlay
Stream
Pixel
OVERLAY_SEL
Blender
8
8
8
VID
Video
Stream
VIDEO_SEL
VIDCLK
VIDVALID
VIDHACT
VIDVACT
VIDFIELD
PLL
and
Clock
Logic
CLKIN
XTI
XTO
CLKO
861_042
2-2
Conexant
D860DSA
CONEXANT [ CONEXANT SYSTEMS, INC ]
