Altera SDI Audio IP Cores - Manual (Page 17)

Avalon-ST Audio Interface
To allow the standard components inside Qsys to interconnect, you must define the Avalon-ST audio
interface. The Avalon-ST audio interface must carry audio to and from physical AES3 interfaces; which
means to support the AES3 outputs, the interface must transport the extra V, U, and C bits. You may create
the P bit.
Each audio block consists of 192 frames, and each frame has channels 1 and 2. Each frame has a combination
of the bits shown in the following figure.
Figure 3-5: AES Format
P Preamble 4 bit U C V
AUX data
or
Audio data 4 bit
AES channel pair 1, sub-frame 2 (CH2)
Audio data 20 bit
The Avalon-ST is a packet-based interface, which carries audio information as a sequence of data packets.
The functions define the types of packets as audio data packets and audio control packets.
This figure shows the audio data and audio control packets for Avalon-ST audio interface.
Figure 3-6: Audio Data and Audio Control Packets for Avalon-ST Audio Interface
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
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
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
SDI Audio IP Functional Description Altera Corporation
Send Feedback
UG-SDI-AUD
Avalon-ST Audio Interface 3-8
2014.06.30