User guide

18–4 Chapter 18: Frame Buffer MegaCore Function
Functional Description
Video and Image Processing Suite January 2013 Altera Corporation
User Guide
Avalon-ST Video Protocol Parameters
The Frame Buffer MegaCore function can process streams of pixel data of the type
listed in Table 18–1.
Stall Behavior and Error Recovery
The Frame Buffer MegaCore function may stall frequently and read or write less than
once per clock cycle during control packet processing. During data processing at the
input or at the output, the stall behavior of the Frame Buffer is largely decided by
contention on the memory bus.
Error Recovery
The Frame Buffer MegaCore function does not rely on the content of the control
packets to determine the size of the image data packets. There is consequently no
error condition such as early or late
endofpacket signal and any mismatch between
the size of the image data packet and the content of the control packet is propagated
unchanged to the next MegaCore function. Nevertheless, the Frame Buffer does not
write outside the memory allocated for each non-image and image Avalon-ST Video
packet, and packets are truncated if they are larger than the maximum size defined at
compile time.
1 For more information about the stall behavior and error recovery, refer to “Stall
Behavior and Error Recovery” on page 1–3.
Latency
Table 18–2 lists the approximate latency from the video data input to the video data
output for typical usage modes of the 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 18–1. Frame Buffer Avalon-ST Video Protocol Parameters
Parameter Value
Frame Width Run time controlled. Maximum value selected in the parameter editor.
Frame Height Run time controlled. Maximum value selected in the parameter editor.
Interlaced /
Progressive
Progressive, although interlaced data can be accepted in some cases.
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, for three channels in sequence where , , and  can be any
color plane:
γβα