User guide

20–2 Chapter 20: Interlacer MegaCore Function
Functional Description
Video and Image Processing Suite January 2013 Altera Corporation
User Guide
Avalon-ST Video Protocol Parameters
The Interlacer MegaCore function can process streams of pixel data of the types listed
in Table 20–1. The Interlacer does not support vertically subsampled video streams.
For example, 4:2:2 is supported but 4:2:0 is not.
Stall Behavior and Error Recovery
While producing an interlaced output field, the Interlacer MegaCore function
alternates between propagating and discarding a row from the input port.
Consequently, the output port is inactive every other row. The delay from input to
output is a few clock cycles when pixels are propagated.
Error Recovery
The Interlacer MegaCore function discards extra data when the endofpacket signal is
received later than expected. When an early
endofpacket signal is received, the
current output field is interrupted as soon as possible and may be padded with a
single undefined pixel.
1 For more information about the stall behavior and error recovery, refer to “Stall
Behavior and Error Recovery” on page 1–3.
Latency
Table 20–2 lists the approximate latency from the video data input to the video data
output for typical usage modes of the Interlacer MegaCore function. You can use this
table to predict the approximate latency between the input and the output of your
video processing pipeline.
The latency is described using one or more of the following measures:
■ the number of progressive frames
■ the number of interlaced fields
■ the number of lines when less than a field of latency
■ a small number of cycles O (cycles)
Table 20–1. Interlacer Avalon-ST Video Protocol Parameters
Parameter Value
Frame Width Run time controlled. (Maximum value specified in the parameter editor.)
Frame Height Run time controlled. (Maximum value specified in the parameter editor.)
Interlaced /
Progressive
Progressive, interlaced data is either discarded or propagated without change as selected in the
parameter editor.
Bits per Color Sample Number of bits per color sample selected in the parameter editor.
Color Pattern
One, two or three channels in sequence or in parallel as selected in the
parameter editor. For example, for three channels in sequence where , 
, and
 can be any color plane:
γβα