Altera Video and Image Processing Suite - Manual (Page 39)

Color Pattern
The organization of the color plane samples within a video data packet is referred to as the color pattern.
This parameter also defines the bit width of symbols for all packet types on a particular Avalon-ST
interface. An Avalon-ST interface must be at least four bits wide to fully support the Avalon-ST Video
protocol.
A color pattern is represented as a matrix which defines a repeating pattern of color plane samples that
make up a pixel (or multiple pixels). The height of the matrix indicates the number of color plane samples
transmitted in parallel, the width determines how many cycles of data are transmitted before the pattern
repeats.
Each color plane sample in the color pattern maps to an Avalon-ST symbol. The mapping is such that
color plane samples on the left of the color pattern matrix are the symbols transmitted first. Color plane
samples on the top are assigned to the symbols occupying the most significant bits of the Avalon-ST data
signal.
Figure 2-8: Symbol Transmission Order
R G B
Symbol transmitted first
Symbol transmitted last
B
G
R Symbol in most significant bits
Symbol in least significant bits
Note: The number of color plane samples transmitted in parallel (that is, in one clock cycle) defines the
number of symbols transmitted in parallel for all packet types on a particular Avalon-ST interface.
A color pattern can represent more than one pixel. This is the case when consecutive pixels contain
samples from different color planes. There must always be at least one common color plane between all
pixels in the same color pattern. Color patterns representing more than one pixel are identifiable by a
repeated color plane name. The number of times a color plane name is repeated is the number of pixels
represented.
Figure 2-9: Horizontally Subsampled Y'CbCr
The figure below shows two pixels of horizontally subsampled Y'CbCr (4:2:2) where Cb and Cr alternate
between consecutive pixels.
Cb Cr
Y Y
In the common case, each element of the matrix contains the name of a color plane from which a sample
must be taken. The exception is for vertically sub sampled color planes. These are indicated by writing the
names of two color planes in a single element, one above the other.
2-12 Static Parameters of Video Data Packets
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2015.05.04
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