Altera Video and Image Processing Suite User Manual
Page 47
To make the protocol flexible and extensible, the Video and Image Processing IP cores obey the following
rules about propagating non-video packets:
• The IP cores must propagate user packets until they receive an end of packet signal. Nevertheless, the
IP cores that buffer packets into external memory may introduce a maximum size due to limited
storage space.
• The IP cores can propagate control packets or modify them on the fly. The IP cores can also cancel a
control packet by following it with a new control packet.
• When the bits per color sample change from the input to the output side of an IP core, the non-video
packets are truncated or padded. Otherwise, the full bit width is transferred.
• The IP cores that can change the color pattern of a video data packet may also pad non-video data
packets with extra data. When defining a packet type where the length is variable and meaningful, it is
recommended to send the length at the start of the packet.
Transmission of Avalon-ST Video Over Avalon-ST Interfaces
Avalon-ST Video is a protocol transmitted over Avalon-ST interfaces.
Table 2-8: Avalon-ST Interface Parameters
The table below lists the values of these parameters that are defined for transmission of the Avalon-ST Video
protocol. All parameters not explicitly listed in the table have undefined values.
Parameter Name
Value
BITS_PER_SYMBOL
Variable. Always equal to the Bits per Color Sample parameter value of
the stream of pixel data being transferred.
PIXELS_IN_PARALLEL
Variable. Always equal to the number of pixels transferred in parallel.
Note: Only aligned pixels supported of frame/line size module
pixels in parallel.
SYMBOLS_PER_BEAT
Variable. Always equal to the number of color samples being
transferred in parallel. This is equivalent to the number of rows in the
color pattern parameter value of the stream of pixel data being
transferred.
READY_LATENCY
1
Table 2-9: Avalon-ST Interface Signal Types
The table below lists the signals for transmitting Avalon-ST Video. The unused signals are not listed.
Signal
Width
Direction
ready
1
Sink to Source
valid
1
Source to Sink
data
bits_per_symbol × symbols_per_beat ×
pixels_in_parallel
Source to Sink
empty
1–8
Source to Sink
startofpacket
1
Source to Sink
2-20
Transmission of Avalon-ST Video Over Avalon-ST Interfaces
UG-VIPSUITE
2015.05.04
Altera Corporation
Interfaces