Altera Video and Image Processing Suite - Manual (Page 38)

Type Identifier Description
13 Ancillary data packet
14 Reserved for future Altera use
15 Control data packet
Figure 2-7: Packet Structure
Start End
Packet type identifier
(4 bits in least significant symbol,
X’s for unused symbols)
Data of the packet
(Split into symbols)
X Symbols can be
transmitted in parallel
(2 in this example)
The Avalon-ST Video protocol is designed to be most efficient for transferring video data, therefore the
symbol bit width and the number of symbols transferred in parallel (that is, in one clock cycle) are defined
by the parameters of the video data packet types.
Video Data Packets
Video data packets transmit video data between the IP cores.
A video data packet contains the color plane values of the pixels for an entire progressive frame or an
entire interlaced field.
The IP core sends the video data per pixel in a raster scan order. The pixel order is as follows:
1. From the top left of the image right wards along the horizontal line.
2. At the end of the current line, jump to the left most pixel of the next horizontal line down.
3. Go rightwards along the horizontal line.
4. Repeat steps 2 and 3 until the bottom right pixel is reached and the frame has been sent.
Static Parameters of Video Data Packets
Two static parameters specify the Avalon-ST interface that video systems use—bits per pixel per color
plane and color pattern.
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.
Note: 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.
UG-VIPSUITE
2015.05.04
Video Data Packets 2-11
Interfaces Altera Corporation
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