User guide

January 2013 Altera Corporation Video and Image Processing Suite
User Guide
9. Clipper MegaCore Function
Core Overview
The Clipper MegaCore function clips video streams. You can configure the Clipper at
compile time or optionally at run time using an Avalon-MM slave interface.
Functional Description
The Clipper MegaCore function provides a means to select an active area from a video
stream and discard the remainder.
The active region can be specified by either providing the offsets from each border, or
by providing a point to be the top-left corner of the active region along with the
region's width and height.
The Clipper can deal with changing input resolutions by reading Avalon-ST Video
control packets. An optional Avalon-MM interface allows the clipping settings to be
changed at run time.
Avalon-ST Video Protocol Parameters
The Clipper MegaCore function can process streams of pixel data of the types listed in
Table 9–1.
Stall Behavior and Error Recovery
The Clipper MegaCore function stalls for a few cycles between lines and between
frames. Its internal latency is less than 10 cycles. During the processing of a line, it
reads continuously but the Clipper only writes when inside the active picture area as
defined by the clipping window.
Table 9–1. Clipper Avalon-ST Video Protocol Parameters
Parameter Value
Frame Width
Maximum frame width is specified in the parameter editor, the actual value is read from control
packets.
Frame Height
Maximum frame height is specified in the parameter editor, the actual value is read from control
packets.
Interlaced /
Progressive
Either. Interlaced inputs are accepted but are treated as progressive inputs.
Bits per Color Sample Number of bits per color sample selected in the parameter editor.
Color Pattern
Any combination of one, two, three, or four channels in each of sequence or
parallel. For example, if three channels in sequence is selected where , , and 
can be any color plane:
γβα