Altera Serial Digital Interface (SDI) MegaCore Function User Manual
Page 110
4–22
Chapter 4: SDI Audio IP Cores
Avalon-ST Audio Interface
Serial Digital Interface (SDI) MegaCore Function
February 2013
Altera Corporation
User Guide
shows the audio data and audio control packets for Avalon-ST audio
interface.
The Avalon-ST audio protocol separates the audio data from the control or status data
to facilitate audio data processing. The protocol defines that the data is packed LSB
first, which matches the AES3 data. The audio data size is configurable at compile
time and matches the audio data sample size. Including the aux, the audio data word
would be 24 bits.
In Avalon-ST audio, the data is packed as 24 bit symbols, typically with 1 symbol per
beat [23:0]. The core transmits the audio control data as a packet after the audio data
to meet the latency requirements.
The packet type identifier defines the packet type. The packet type identifier is the
first value of any packet, when the start of packet signal is high. The audio data packet
identifier is 0×A and the audio control data packet identifier is 0×E.
lists
the packet types.
The preamble data, XYZ from AES, describes whether the data is at the start of a block
and which channel the audio refers to. In Avalon-ST audio protocol, you are not
required to transport the preamble data because the information stored in the data is
described by the start of packet, end of packet, and channel signals.
Figure 4–6. Audio Data and Audio Control Packets for Avalon-ST Audio Interface
Note to
(1) The sequence of audio control packets begins with V bit, U bit, and finally C bit. The audio control packets for U and C bits are similar to V bits.
D0
D192
...
V0
V7
...
...
MSB
Audio Data Packet
(1)
Audio Control Packet
LSB
MSB
LSB
AUX data (4 bits)
Audio data (20 bits)
AUX data (4 bits)
Audio data (20 bits)
MSB
LSB
MSB
LSB
1st frame
of V bit
24th frame
of V bit
192nd frame
of V bit
Table 4–29. Avalon-ST Packet Types
Type Identifier
Description
0
Video data packet
1–8
User packet types
10
Audio data packet
14
Audio control data packet
15
Video control data packet
9–15
Reserved