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Biamp Systems

Using multiple networked audio protocols

A notable feature of the Tesira platform is the ability to combine and synchronize audio from AVB, Dante, and CobraNet sources in a single system, even a single device.

Tesira firmware versions 2.4 and higher support several features for enchanced audio networking, providing greater flexibility for the design and installation of both single and multi-protocol systems.

New features in brief:

  • A Tesira system can support multiple AVB, CobraNet, and Dante networks.
     
  • An external media network (i.e., CobraNet, Dante, or 3rd-party AVB) can be assigned at the system's Clock Master, allowing a Tesira system to synchronize to a 3rd-party device or system.
     
  • Multiple Tesira systems can more easily and flexibly share common network infrastructure.

Media network configuration

Media networks are now managed in a new dialog, in which multiple AVB, CobraNet, and Dante networks can be added and named, and the master media clock network selected.

AVB, Dante and CobraNet input/output blocks can be assigned to one of the system’s named networks, allowing AVB streams, Dante flows, and CobraNet bundles to be associated with a specific media network. Additionally, any one network can be selected as the clock master for the Tesira system, regardless of protocol.

Default behavior

Use of user-defined media networks is optional.

Tesira automatically creates a default network of each type, and media network input/output blocks will be automatically assigned to their corresponding default network. The default settings will configure the system's audio media networks to behave in the same way as earlier versions of Tesira. Therefore, a system can be upgraded to Tesira 2.4 without reconfiguring the software.

Adding and managing

To add new media networks, and assign the system's Clock Master network, select the System menu, then select Media Network then Setup. This will open the Media Networks Setup dialog.

The three default networks cannot be deleted, but the Clock Master can be selected, and the reporting of clock synchronization faults can be disabled on the default Dante and CobraNet networks.

By default, the dialog will look like this:

Media Networks Setup - Default

Figure 1 - Media Networks Setup, default settings

To add new networks, click the Add button. Select the desired Network Type, and edit the name if required. Any of the networks can be assigned as the system's Clock Master. Here is an example:

Media Networks Setup - Edited

Figure 2 - Media Networks Setup, example configuration

Clock Master

Checking the Clock Master check box for a media network tells the Tesira system that the master clock will be a device on that media network. It tells the Tesira system to synchronize to the selected network and to propagate its clock to the other media networks. See the section Clock Propagation below.  

Note: depending on the design of the audio system, the actual master clock device could be a device in that Tesira system, a device from another Tesira system sharing the same media network, or a 3rd party device on the media network.

Assigning blocks to a network

When adding an AVB.1, Dante or CobraNet input or output block to a file, a named network of the corresponding type can be chosen from the drop-down list in the initialization dialog box. Here is an example:

Input Block - Initiallization

Figure 3 - Input/output Initialization dialog

After initialization, the selected Network can be changed in one of two ways. One method is to right-click on the block then select Edit Block Parameters

The other method to change network assignment is to select the block then open the DSP Properties tab of the Properties window. The network assignment can be changed in the Network field. Here is an example of this method:


Input Block - Network Re-assignment

Figure 4 - input/output block network assignment

Assigning blocks to a device

AVB.1, Dante or CobraNet blocks can be assigned to a specific device in the same way as any other input/output or DSP blocks. In the DSP Properties tab of the Properties window, in the Allocated to Unit field, select the correct device.

To lock this assignment, and prevent the compiler from over-writing it, set Fixed in Unit to TRUE.

Input Block - Device Assignment

Figure 5 - input/output block device assignment

Network diagrams

The new features of Tesira 2.4 allow a Tesira system to use a collection of media networks in more complex arrangements than before, and it is important to remember that only one of the networks can be identified as the clock source of the system.

A system can be viewed as a tree which has the Clock Master media network at its root. Media network connections which lead toward the Clock Master are “upstream” connections, and those which lead away from it are “downstream” connections. A media clock is propagated from “upstream” to “downstream” connections.

To help make the connections easy to understand, a Tesira System’s media network tree can be viewed in the new Media Networks Diagram window. Select the System menu, then Media Networks, then Diagram.

Here is an example, annotated to show the direction of media clock propagation:

Media Networks Diagram

Figure 6 - Media Networks Diagram, example system

Essential rules

General

  1. A system of Tesira devices can support only a single media clock domain, i.e. Tesira devices must be synchronized to the same clock source to share digital audio over a media network.
     
  2. In a multi-device system, all Tesira devices with an AVB, Dante, or CobraNet media interface must have at least one network media connection which can be traced back to the Clock Master media network. Consequently:
     
    • A system cannot contain unconnected sub-groups (groups which share media connections with each other but not with the rest of the system).
  3. Up to three layers of media networks are supported. For examples, see the Tesira help page:  Media Clock Topologies.

Implicit AVB

  1. Implicit AVB connections (connections between Tesira devices, created by the compiler and represented by blue dotted lines in Tesira software) are made on the AVB Default network only.
     
  2. Expanders must use implicit AVB connections. Therefore, the Input/Output blocks for audio expanders will be automatically assigned to the AVB Default network.
     
  3. Because of 1 and 2 above, any system which contains audio expanders or uses implicit AVB connections must use the AVB Default network.
     
  4. 1722.1 compatible AVB.1 blocks can be used on both the AVB Default network and user-defined AVB networks.

CobraNet, Dante & AVB.1

  1. SERVERs are fitted with one AVB card by default and have one user-configurable slot which can be fitted with any Tesira option card, including a Dante or CobraNet card, or a second AVB card.
     
  2. SERVER-IO devices have three user-configurable slots which can be fitted with media networking option cards, with a supported maximum for each type of card of: 1 x AVB; 2 x  Dante; 2 x CobraNet. 
     
  3. Implementing a second AVB network in a Tesira system requires a Tesira device with two AVB cards installed, one to connect to the AVB Default network and one to connect to the user-defined AVB network. Only SERVERs support two AVB cards.
     
  4. TesiraFORTÉ devices are available with AVB and Dante interfaces only.

Clock Propagation

  1. Clock propagation between Tesira devices on the AVB Default network is managed automatically by the compiler.
     
  2. To ensure clock propagation in the Tesira system matches the Media Networks Diagram, the compiler will automatically set each CobraNet card's conductor priority and each Dante card's Preferred Master flag.
     
  3. A system of Tesira devices may be synchronized to an external, 3rd party device. To accomplish this, a 3rd party device must be placed on the selected Clock Master network (see Media Networks Setup dialog).
     
  4. A Tesira system can be synchronized to a 3rd party AVB device by placing an AVB.1 input block on the AVB Default network or a user-defined AVB network (if assigned as the Clock Master). An AVB controller, such as Riedel AVB Manager, must be used to configure the Tesira system to synchronize to the incoming AVB stream.

  5. A Tesira system can be synchronized to a 3rd party Dante or CobraNet device by placing the appropriate input block on the network assigned as the Clock Master. The Tesira system will synchronize automatically.

  6. Any media network (AVB, CobraNet or Dante) can have only one master clock source. If N Tesira systems are connected to the same Dante/CobraNet network, then that network must be the clock source network for at least N-1 of the connected Tesira systems.

    For example, if two or more Tesira systems share a common Dante network:
     
    • The Dante network can be the master clock for all Tesira systems, or
       
    • The Dante network can derive its master media clock from one of the Tesira systems, but it must then be the master media clock for all other connected Tesira systems.

Tesira systems sharing a common network

An additional media networking change in Tesira 2.4 concerns how Tesira devices synchronize with each other over an AVB media network.

2.3 & Earlier

In Tesira versions 2.3 and earlier, the rule was simple: Tesira devices which discovered each other on the control network would assume they were connected to the same AVB media network and attempt to synchronize with each other.

In installations of multiple Tesira systems, which shared a common control network but not a common AVB media network, this could result in a synchronization failure in one or more of the Tesira systems.

New for 2.4

In Tesira version 2.4 the rule has been changed, making it easier to work with larger and more complex installations:

Only Tesira devices in the same system will assume they are part of the same AVB media network and try to synchronize with each other.

A single Tesira configuration file defines a single media clock domain. Tesira devices programmed in same file will attempt to synchronize with each other; Tesira device programmed in separate files will not try to synchronize with each other.