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AES67 and the Sienda TSN Stack, User Experience

Abstract

Sienda and users of the Sienda Stack have identified a need for products in the ProAV space to support both AVB/Milan and AES67.

Technical considerations for supporting AES67 in the Sienda Stack are discussed here.

AES67 will be added to the Sienda Stack in two distinct phases:

  • AES67 streaming for AVB devices
  • standalone AES67 support

The second will only be implemented if required and supported by a customer.

This page discusses the expected user experience.

AES67 streaming for AVB devices

In this use case the ProAV device is primarily an AVB/Milan device, and inhabits an AVB network. The primary streaming media protocol between AVB devices on this network will be the AVB stream protocol (1722). If however, an AES67 device is added to the network, then streams may be established between the AVB devices and the AES67 device using AES67.

an AVB network with AVB/Milan devices streaming audio

an AES67 device is added to the AVB network and AVB/Milan devices supporting AES67 may stream with the AES67 device

Configuration of the device

To configure a Sienda AVB/Milan device to send or receive an AES67 stream, simply set the stream format of one of the talker or listener streams to AES67, using the Sienda Controller:

If both talker and listener devices (sender and receiver in AES67 parlance) are AVB/Milan devices that support AES67, then you can initiate an AES67 stream between them by connecting them via the Sienda Controller in exactly the same way as you would for an AVB stream:

If the stream format is set to AES67 then the stream flowing will now be an AES67 stream. Of course it may not make much sense to do this, as you lose the benefits of AVB, and on a single network it would be better to use AAF as the stream format in this case. BUT, if the two devices are separated by a non-AVB network segment, then AES67 could flow across the non-AVB segment (as could IP-encapsulated AVB).

If the other device only supports AES67 then the stream must be established at each end independently. For the Sienda Stack device, right click on the stream (talker or listener) and select 'Manually start stream'. This will start the AES67 stream on the Sienda device end. To set or obtain the AES67 stream address, right click on the stream and select 'Show stream parameters'. Then use the vendor proprietary method of starting the AES67 stream for the other (AES67 only) device.

Limitations and considerations

PTP sync

AVB/Milan uses gPTP (802.1AS) whereas the majority of AES67 devices use PTPv2. This means that when AES67 devices and AVB/Milan devices coexist on the same network, both variants of PTP must be supported. To allow streams to flow between AVB/Milan devices and AES67 devices, the two PTP variants must also be synchronised. This can be achieved by using a PTP GrandLeader device that supports both gPTP and PTPv2 (at the same time), for example the Brainstorm DXD-16. Alternatively a gPTP<->PTPv2 bridging device could be used (please contact Sienda for information about such devices).

Pros and Cons of the Sienda AES67 implementation

Pros:

  • allows streaming of audio between an AVB/Milan supporting AES67 and a proprietary AES67 device
  • allows streaming of AVB streams and AES67 streams at the same time

Cons:

  • require an AVB network (at least for the AVB/Milan devices to connect to)
  • require synchronisation between gPTP and PTPv2, or a common GrandLeader device