Altera Video and Image Processing Suite - Manual (Page 46)

Figure 2-15: One Symbol in Parallel
Control data, reference numbers to Table 4-5
Control data packet type identifier
(4 bits in least significant symbol,
X’s for unused symbols)
Start End
3 15 9 6 8 5 2 7 4 1
Ancillary Data Packets
Ancillary data packets send ancillary packets between IP cores.
Ancillary data packets are typically placed between a control data packet and a video data packet and
contain information that describes the video data packet, for example active format description codes.
An ancillary data packet can contain one or more ancillary packets; each ancillary packet starts with the
hexadecimal code 0, 3FF, 3FF.
Note: The format of ancillary packets is defined in the SMPTE S291M standard.
IP cores are not required to understand or process ancillary data packets, but must forward them on, as is
done with user-defined and Altera-reserved packets.
User-Defined and Altera-Reserved Packets
The Avalon-ST Video protocol specifies seven packet types reserved for use by users and five packet types
reserved for future use by Altera.
The data content of all of these packets is undefined. However the structure must follow the rule that the
packets are split into symbols as defined by the number color plane samples sent in one cycle of the color
pattern.
Unlike control data packets, user packets are not restricted to four bits of data per symbol. However when
a core reduces the bits per pixel per color plane (and thus the bit width of the symbols) to less than the
number of bits in use per symbol, data is lost.
Packet Propagation
The Avalon-ST Video protocol is optimized for the transfer of video data while still providing a flexible
way to transfer control data and other information.
UG-VIPSUITE
2015.05.04
Ancillary Data Packets 2-19
Interfaces Altera Corporation
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