Configuring Audio Over IP

AERO units which support audio over IP (AoIP)

AERO.8000
AERO.20
AERO.200
AERO.2400
AERO Enterprise

Note: AERO.10, 100 and 2000 units have Livewire+ AES67 configuration submenus found in several locations. For example:
System > System > Livewire. Outputs > Livewire Stereo Output >. Instance > Output > Livewire.
Livewire+/AES67/SMPTE2110-30/31 are NOT supported in AERO.10, 100 and 2000 and these menus should not be used.

Supported AoIP formats

AES67 interop mode/SMPTE 2110-30/31 Profile A using PTP clock.
Livewire+ using 1ms packetization and Livewire clock.

Note that AES67/SMPTE 2110-30/31 are strictly AoIP specifications. There is no discovery method. Stream discovery for AES67/SMPTE ST 2110 workflows is typically handled by AMWA NMOS IS-04.

Livewire+ AoIP streams includes Livewire discovery even when operated in AES67 compliant mode. This mode is selected when 1ms packetization is selected for a Livewire+ output.

At the time of this writing, AERO units do not support NMOS-04 or 05. However, the AERO processors named above do support manual configuration of AES67/SMPTE 2110-30/31 streams. The audio port and RTP type can be chosen manually or SDP files can be manually imported or exported in some units.

Reference Clock for AoIP

AoIP streams require a reference clock. This is a different timing reference then AES-3 clock or video reference. In AERO processors the source for AoIP timing can be a Livewire clock or a PTP master clock.

Note: In a facility that has video, AES-3 audio and AoIP ALL timing/sync signals MUST have the same master time reference if synchronization between all baseband and AoIP signals is desired. This reference is usually a GPS locked master clock generator that has video, AES-3 and PTP clock outputs.

Configure the AoIP clock:

Navigate to: System > System > AoIP.
Click the Clock button
In the Clock mode drop-down menu, select a clock mode:
1. PTP (IEEE-1588) for AES67
  1. select the PTP clock domain
2. Livewire clock for use with Livewire streams

Note: PTP or Livewire clock must be supplied to the AERO. AERO processors do not generate Livewire or PTP clock.

Select the Address Display type

AES67 displays the multicast stream address.
Livewire displays the Livewire channel number.

Note: This setting impacts how the data is displayed only. Under the hood, a 2-ch Livewire stream at channel 25001 is a multicast stream with an address of 239.192.97.169. This is just two different ways of displaying the same information.

AoIP Sources

AoIP sources are selected for inputs to AMX instances

AMX5.1

Receive 1+2 (8ch): Eight-channel stream,

DRC 1 inputs = channels 1-6.

When audio is present on ch 3 (Center) OR ch 5 (Left surround) OR ch 6 (Right Surround) then the source is 5.1

When no audio is present on ch 3 (Center) OR ch 5 (Left surround) OR ch 6 (Right Surround) then the source is stereo (2.0) on ch 1/2.

DRC 2 inputs = channels 7/8.

Receive 1 (6ch):

DRC 1 inputs = channels 1-6

When audio is present on ch 3 (Center) OR ch 5 (Left surround) OR ch 6 (Right Surround) then the source is 5.1

When no audio is present on ch 3 (Center) OR ch 5 (Left surround) OR ch 6 (Right Surround) then the source is stereo (2.0) on ch 1/2.

Receive 1 (2ch):

DRC 1 inputs = channels 1/2.

Receive 2 (2ch): Stereo stream containing the input of Program 2 (inputs 7/8).

DRC 2 inputs = channels 7/8

Receive 3 (2ch): Stereo stream containing the input of Program 3 (9/10 Local).

Return: Eight-channel stream, where channels 1-6 are the insert point (return) of Program 1, and channels 7 and 8 are the insert point (return) of Program 2..

When the AMX engine is AMX2.0, these are the stream slots:

Receive 1+2 (8ch): Eight-channel stream, where channels 1-6 are a 5.1-ch input for Program 1 to be downmixed, and channels 7 and 8 are the input of Program 2.
Receive 1 (2ch): Two-channel stream, which is the stereo input stream to Program 1.
Receive 2 (2ch): Stereo stream containing the input of Program 2 (inputs 7/8).
Receive 3 (2ch): Stereo stream containing the input of Program 3 (9/10 Local).
Return: Two-channel stream, which is the insert point (return) of Program 1.

When the AMX engine is AMX5.1, these are the stream slots:

Receive 1+2 (8ch): Eight-channel stream, where channels 1-6 are the 5.1-ch input of Program 1, and channels 7 and 8 are the input of Program 2.
Receive 1 (6ch): Six-channel stream, where channels 1-6 are the 5.1-ch input of Program 1.
Receive 1 (2ch): Two-channel stream, which is the input to channels 1 and 2 of Program 1.
Receive 2 (2ch): Stereo stream containing the input of Program 2 (inputs 7/8).
Receive 3 (2ch): Stereo stream containing the input of Program 3 (9/10 Local).
Return: Eight-channel stream, where channels 1-6 are the insert point (return) of Program 1, and channels 7 and 8 are the insert point (return) of Program 2.

When the AMX engine is AMX5x2, these are the stream slots:

Receive 1A (2-ch): Two-channel stream, which is the input of Program 1.
Receive 1B (2-ch): Two-channel stream, which is the input of Program 1B.
Receive 1C (2-ch): Two-channel stream, which is the input of Program 1C.
Receive 2 (2-ch): Stereo stream containing the input of Program 2 (7/8).
Receive 3 (2-ch): Stereo stream containing the input of the 9/10 Local.
Return: Two-channel stream, which is the insert point (return) of Program 1.

AoIP Input Status and Stream Slot Pages

Figure 1: Example AoIP stream receive configuration page

The left side of the AoIP input page (Instance number > Input > AoIP) provides tabs for displaying the input status, or selecting a stream slot to configure, for example, Receive 1+2 (8ch).

When a stream slot is selected (highlighted), its status, statistics, and controls are displayed immediately to the right of the Status and stream slot tabs.

Reset Statistics

Click the Reset Statistics button to reset and restart the statistics count. This can be useful for troubleshooting or when changing sources.

Channel Field

This field lets you enter the multicast IP address of the source stream.

The default port number that AES67 and Livewire+ streams use is 5004. You can change the port number, if needed. The AERO supports receiving streams at different port numbers. This information, along with RTP header type, is reflected in the SDP that can be uploaded into the AERO. You can also enter a port number with the stream address.

To change a source stream address (and its port number):

Choose Instance (1 or 2) > Input > AoIP.
Click the source stream tab.
In the Channel field, enter the AES67 multicast IP address or Livewire channel number.
Add the port number to the end of the AES67 address or the Livewire channel number, separating the port number with a colon.
Example: Using an AES67 multicast address of 239.196.97.169, the default port is 5004.
To change this to port 5006, enter 239.196.97.169:5006.

Figure 2: AoIP stream display with non-default port value

Press the Take button. The display updates to include the port number in the status and multicast address. Additionally, if you download the SDP file, the port number is contained in the SDP file.

Channel List

This control is active when using Livewire streams. This list includes all available Livewire streams identified on the AoIP network, allowing easy selection of the desired source stream. Since AES67 streams do not include discovery, they will not populate in the Channel List.

Upload AES67 SDP

This control lets you load an SDP file for an incoming AES67 stream. The SDP file contains information regarding the input stream, including sample rate, number of audio channels, multicast address and port number, and RTP header information. This information is necessary for AES67 audio streams, whereas Livewire streams contain this.

A screenshot of a computer Description automatically generated

Figure 3: SDP example

Take

The Take control applies all changes made to the input stream and updates the SDP information. After any changes are made to the stream, press the Take button. You can upload the updated SDP file to the AERO.

Destination Name

This is a custom name you can use for your receiver (for example, a name that is easier to understand than an IP address).

Fifo Buffer

This control lets you adjust the length of the input buffer for incoming AoIP streams. The default buffer size is 30 ms.

To adjust the Fifo Buffer:

Click the control and drag left or right to decrease or increase the size.

Sample Rate Conversion

When AES67 or Livewire streams are used, a reference clock signal must be applied to the AERO unit. The unit cannot generate reference clock for AoIP. This clock will either be PTP (IEEE-1588) or Livewire clock, depending on which AoIP format is being used.

To enable Sample Rate Conversion:

Click on the Sample Rate Conversion box, so that is turns yellow.

Sample rate converters are supplied for each AoIP input stream, which allow different clock domains to be supported, PTP or Livewire clock for AoIP streams, and SDI, AES3, or VRef for the baseband I/O.

Note: Sample Rate Converters are provided to manage audio from different clock domains. Unless the reference clock for the baseband audio in the overall system (SDI, AES3) is derived from the AoIP clock source, sample rate converters should be enabled.

Important! Coded audio, such as any Dolby audio, cannot be passed through a sample rate converter without being destroyed.

Assign and Memory Slots

The furthest right column on a stream slot page includes memory slots to store the address and other relevant information regarding commonly used input streams.

To assign the currently active stream to a memory slot:

Click the Assign button box (so that it turns yellow).
Select the desired memory slot to store the information in.

To clear a memory slot:

Store an empty stream address/channel to that memory location.

AoIP Outputs

Similar to AoIP inputs, the outputs operate in the concept of slots. There are multiple slots, which can transmit output streams simultaneously.

When the AMX engine is AMX2.0, these are the stream slots:

Send 1 (2-ch): Two-channel stream, which is the output of Program 1.
Send 2 (2-ch): Stereo stream containing the output of Program 2 (7/8).
Send 3 (2-ch): Stereo stream containing the output of the 9/10 Local.
DD+ Encoder Out*: Stereo stream containing the output of the Dolby Digital Plus encoder for Program 1 when the Dolby transcoder option is installed.
DD+ Encoder Out 2*: Stereo stream containing the output of the Dolby Digital Plus encoder for Program 2 (7/8) when the Dolby transcoder option is installed.
Send: Two-channel stream which is the insert point (send) of Program 1.

When the AMX engine is AMX5.1, these are the stream slots:

Send 1+2 (8-ch): Eight-channel stream, where channels 1-6 are the 5.1-ch output of Program 1, and channels 7 and 8 are the output of Program 2.
Send 1 (6-ch): Six-channel stream containing the 5.1-channel output of Program 1.
Send 2 (2-ch): Stereo stream containing the output of Program 2.
Send 3 (2-ch): Stereo stream containing the output of the 9/10 Local.
DD+ Encoder Out*: Stereo stream containing the output of the Dolby Digital Plus encoder for Program 1 when the Dolby transcoder option is installed.
DD+ Encoder Out 2*: Stereo stream containing the output of the Dolby Digital Plus encoder for Program 2 (7/8) when the Dolby transcoder option is installed.
Send: Eight-channel stream, where channels 1-6 are the insert point (send) of Program 1, and channels 7 and 8 are the insert point (send) of Program 2.

When the AMX engine is AMX5x2, these are the stream slots:

Send 1A (2-ch): 2-channel stream, which is the output of Program 1.
Send 1B (2-ch): 2-channel stream, which is the output of Program 1B.
Send 1C (2-ch): 2-channel stream, which is the output of Program 1C.
Send 2 (2-ch): stereo stream containing the output of Program 2 (7/8)
Send 3 (2-ch): stereo stream containing the output of the 9/10 Local
DD+ Encoder Out*: stereo stream containing the output of the Dolby Digital Plus encoder for Program 1 when the Dolby transcoder option is installed.
DD+ Encoder Out 2*: stereo stream containing the output of the Dolby Digital Plus encoder for Program 2 (7/8) when the Dolby transcoder option is installed.
Send: Two-channel stream which is the insert point (send) of Program 1.

Sample Rate Conversion

Similar to the AoIP inputs, there are sample rate converters in the AoIP output path to help manage the two different clock domains between the AoIP stream (PTP or Livewire clock) and the audio processing engine and baseband reference clock.

The difference here is that the output SRCs are always in the AoIP output path and cannot be bypassed.

Note: Sample rate converters are provided to manage audio from different clock domains (baseband/audio engine and AoIP). Encoded audio of any type (such as Dolby, DTS, and MPEG) cannot be transmitted through a sample rate converter.

AoIP Output Status and Stream Slot Pages

Figure 4: AoIP Output Stream configuration tab

The left side of the AoIP output page (Instance n > Output > AoIP) provides tabs for displaying the output status, or selecting a stream slot to configure, for example, Send 1+2 (8ch).

AoIP Output Stream Slot Status and Statistics

When an output stream slot is selected (highlighted), its status, statistics, and controls are displayed immediately to the right of the Status and stream slot tabs.

Click the Reset Statistics button to reset and restart the statistics count. This can be useful for troubleshooting or when changing sources.

Tip! After you change stream settings, it is good practice to clear out the previous statistics. Click the Reset Statistics button to reset and restart the statistics count. This can also be useful for troubleshooting or when changing sources.

Figure 5: AoIP output stream status and statistics

The first line at the top of the page provides the stream address, port number (if not using the default), and connection status. When the AoIP address display (System > System > AoIP) is set to AES67, the output stream’s multicast IP address is displayed. When the AoIP IP address display is set for Livewire, the display indicates the Livewire+ channel selected. These are two different methods of displaying the same information. For more information about Livewire+, visit the Telos Alliance website (https://www.telosalliance.com).

The Stream Mode line includes the Stream Mode, its packet time (ptime), and RTP header value. The ptime is the number of packets per second.

Figure 6: AoIP output Stream Mode and RTP header value

Stream Mode = AES67, Standard, or LW Surround.

AES67 interop streams have a packet time of 1 ms or 1000 packets per second.
Standard streams are Livewire standard streams, which have a packet time of 5 ms, or 200 packets per second.
LW Surround streams are Livewire Surround streams, which have a packet time of 1.25 ms or 800 packets per second.

The RTP header/payload type is the third number shown in this line.

Reset Statistics

Click the Reset Statistics button to reset and restart the statistics count. This can be useful for troubleshooting or when changing sources.

Channel

The Channel field is where you enter the desired multicast address or Livewire channel number for the output stream. The information can be entered in either format.

The default port number that AES67 and Livewire+ streams use is 5004. You can change the port number, if needed. The AERO supports sending streams at different port numbers. This information, along with RTP header type, is reflected in the SDP that the AERO generates, so that receiving devices know the values to use. You can also enter a port number with the stream address.

To change an output stream address (and its port number):

Choose Instance (1 or 2) > Output > AoIP.
Click the output stream tab.
In the Channel field, enter the AES67 address or Livewire channel number.
Add the port number to the end of the AES67 address or the Livewire channel number, separating the port number with a colon.
With an AES67 multicast address of 239.196.97.190, the default port 5004 is used.

Figure 7: AoIP Output Stream using default port value of 5004

To change the default port (for example, to port 5006), enter 239.196.97.169:5006.

Figure 8: AoIP Output Stream using port value of 5006

Press the Take button. The display updates to include the port number in the status and multicast address. Additionally, if you download the SDP file, the port number is contained in the SDP file.

Take

The Take control applies all changes made to the output stream and updates the SDP information. After any changes are made to the stream, press the Take button. You can then download the updated SDP file using the Download AES67 SDP control for the stream slot.

Name

The Name field lets you apply a user-friendly name to the output stream.

Label

This is what is displayed on other devices when using Livewire discovery.

Enable

The Enable control turns the output stream on or off.

To enable the output stream:

Click on the Enable box, so that is turns yellow.

Stream Mode

This drop-down menu provides two options for output streaming.

AES67 8ch (1 ms): Standard low-latency 1 ms AoIP stream in AES67 or stereo Livewire.
LW Surround (800 pps): 1.25 ms Livewire surround stream

Fifo Buffer

This control lets you adjust the buffer length for AoIP output streams. The default buffer size is 30 ms.

To adjust the Fifo Buffer:

Click the control and drag left or right to decrease or increase the size.

Override PT (Payload Type)

This field lets you change of the RTP Type value inserted into the output stream. The RTP Type is automatically set by the stream configuration. However, the default value can be overwritten and set to a different value, if needed. This setting is configurable on a stream-by-stream basis.

A screenshot of a computer

Figure 9: Setting RTP header in the Override Payload Type field