Altera Video and Image Processing Suite - Manual (Page 201)

The user packets are never repeated and they are not dropped as long as memory space is sufficient. The
control packets are not stored in memory.
• The input control packets are processed and discarded by the writer.
• The output control packets are regenerated by the reader.
When a frame is dropped by the writer, it keeps the preceding non-image data packets and sends with the
next frame that is not dropped. When a frame is repeated by the reader, it is repeated without the packets
that preceded it.
The behavior of the Frame Buffer IP core is not determined by the field dimensions announced in the
Avalon-ST Video control packets and relies exclusively on the
startofpacket
and
endofpacket
signals
to delimit the frame boundaries. The Frame Buffer IP core can consequently handle and propagate
mislabeled frames. You can use this feature in a system where dropping frame is not an acceptable option.
The latency introduced during the buffering could provide enough time to correct the invalid control
packet.
The buffering and propagation of image data packets incompatible with preceding control packets is an
undesired behavior in most systems. Dropping invalid frames is often a convenient and acceptable way of
dealing with glitches from the video input. You can parameterize the Frame Buffer IP core to drop all
mislabeled fields or frames at compile time. Turning on the Frame repetition parameter guarantees that
the reader keeps on repeating the last valid received frame— freezes the output—when the input drops.
Color Format
Color definitions for YCbCr and RGB combinations are different.
Table 14-1: Color Definition for 8-bit YCbCr and RGB Combinations
Any value from 0 to 255 that is not valid for YCbCr format may be valid for RGB format.
Color 8-bit YCbCr 8-bit RGB
Light gray 180, 128, 128 180, 180, 180
Yellow 162, 44, 142 180, 180, 16
Cyan 131, 156, 44 16, 180, 180
Green 112, 72, 58 16, 180, 16
Magenta 84, 184, 198 180, 16, 180
Red 65, 100, 212 180, 16, 16
Blue 35, 212, 114 16, 180, 16
White 235, 128, 128 235, 235, 235
Black 16, 128, 128 16, 16, 16
14-4 Color Format
UG-VIPSUITE
2015.05.04
Altera Corporation Frame Buffer IP Cores
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