User guide

3–4 Chapter 3: Interfaces
Avalon-ST Video Protocol
Video and Image Processing Suite January 2013 Altera Corporation
User Guide
Static Parameters of Video Data Packets
The following two static parameters specify the Avalon-ST interface that video
systems use:
Bits Per Pixel Per Color Plane
The maximum number of bits that represent each color plane value within each pixel.
For example R’G’B’ data of eight bits per sample (24 bits per pixel) would use eight
bits per pixel per color plane.
1 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.
Color Pattern
The organization of the color plane samples within a video data packet is referred to
as the color pattern. This color pattern cannot change within a video data packet.
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 as shown in
Figure 3–3.
1 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.
Figure 3–3. Symbol Transmission Order
RGB
Symbol transmitted first
Symbol transmitted last
B
G
R
Symbol in most significant bits
Symbol in least significant bits