Multiple Channels of Audio & MPX over IP


The APT MULTI-CHANNEL CODEC is a compact and efficient solution for the transport of multiple channels of audio or MPX content over IP links. It can support up to 16 channels of audio within a single unit of rackspace - and even more IP streams when using multicast or multiple unicast technology.

A Dante Interface module enables direct connection to Dante or AES 67 networks. APT DANTE

The 1RU frame can accommodate up to 4 AoIP modules, each equivalent to a stand-alone stereo duplex codec combining audio, dual IP transport and auxiliary data on board. It offers the entire range of audio formats and modes meeting the audio industry’s requirements: simplex, duplex, AES/EBU, AES/EBU with analog backup, analog with HI/LO or 600Ω impedance.



Audemat ScriptEasy Powerful Performance

  • Supports up to 16 channels of Audio in 1RU and even more IP streams with Multicast or Multiple Unicast   
  • Outstanding audio quality with low delay, cascade-resilient aptX Enhanced 
  • Many other standards & coding options available 
  • Robust DSP-based platform for mission-critical operation
  • Redundant Power Supplies as standard, no single point of failure
  • Hot-swappable cards enable uninterrupted audio
  • Support of Specific-Source Multicast (SSM)


Audemat ScriptEasy Powerful Control

  • NTP System Time option for program time-alignment on multiple Decoder sites
  • User-configurable suite of audio, link, sync and PSU alarms
  • Supports the majority of protocols in compliance with Tech 3326 standard for IP compatibility
  • Support for SNMP
  • Support VLANs and virtual IP interfaces for flexible network integration
  • Network security features with firewall capability


Audemat ScriptEasy Powerful Savings

  • Flexible & modular system that can scale according to your requirements
  • Supports up to 4 AoIP modules, each  equivalent to a stand-alone stereo duplex codec in a 1U rack space
  • SureStream Technology* for ultra-reliable delivery over affordable public IP connections
  • Seamless, affordable migration from T1/E1 to IP networks using same frame


  • Transports up to two stereo audio channels per module
  • Deliver up to 24 IP audio streams per module
  • 192/128kHz Sampling supports Digital MPX over AES and fully digital transfer*
  • Simplex and duplex operational modes
  • Optional Dante Interface enabling direct connection to Dante /AES67 network
  • Analog MPX I/O interface allows transport of two analog MPX signals or one MPX signal in duplex mode
  • Point-to-Point and Point-to-Multipoint operation
  • Content Time Alignment for Multi-Frequency FM networks utilizing NTP
  • Four Independent Clock Domains per module
  • Supports Dynamic DNS for global accessibility by hostname rather than IP address
  • Supports UPnP IGD protocol for configuration of UPnP enabled gateways (routers)
  • Forwarding of audio or non-audio (such as PAD or HD Exporter data) UDP Streams
  • Supports “Diffserv” Quality of Service (QoS) on variable DSCP values
  • Support of VLANs and virtual IP interfaces enables multi-network integration for streaming and management
  • Performance monitoring on each individual IP stream
  • User selectable packet size for each stereo audio channel
  • Configurable delay-jitter buffer for each receive IP stream (1 ms to 5000 ms)  
  • Headphone socket for audio monitoring
  • Supports APT’s award winning SureStream for high quality audio over open Internet links
  • Reliable DSP-based architecture


* Cost option


AoIP Card Front

The APT AoIP Codec Module offers audio encoding/decoding, IP transport, management and auxiliary data on a single, plug-in module. This enhances the Audio over IP performance of the APT Multi-Channel Codec System as well as increasing its scalability and flexibility.

Fully compatible with the many hundreds of existing units already deployed worldwide, each AoIP card can deliver two independent stereo audio channels on multiple IP streams using multiple unicast or multicast.

The APT AoIP codec module offers the entire range of audio formats and modes meeting the audio industry’s requirements: simplex, duplex, AES/EBU, AES/EBU with analog backup, analog with HI/LO or 600Ω impedance.

The module offers the same broadcast-grade audio for which the Multi-Channel Frame is renowned with support for a wealth of standards such as: Linear PCM 16/24Bit, aptX® Enhanced16/24Bit, MPEG1/2 LII, MPEG2 HE-AAC & HE-AACv2, MPEG4 AAC LC/LD/ELD, HE-AACv1/v2 .

Supporting MPX over IP

The APT AoIP Codec Module is also able to support 85kHz of audio bandwidth and scale the sample rate to 192kHz, enabling a digital MPX signal to be sent on an AES stream. The output of the audio codec can therefore be transferred directly to the modulator of the exciter. This 100% digital path eliminates D/A and A/D conversions which may cause degradation of signal quality and could introduce distortion.

AoIP Card rear


A separate Input/Output module is available for the APT AoIP MULTI-CHANNEL CODEC which enables the transmission of analog MPX signals in duplex and simplex mode as well as AUX and GPIO signals. The mix of digital and analog MPX transmission on the same frame allows seamless migration from analog MPX processing to digital processing regardless of the transmitter type.

Specific benefits of APT MPX transmission include:

  • Dual Simplex Transmission
    In simplex mode the MPX Codec can send or receive 2x MPX signals
  • Redundant IP Transport
    MPX signals for FM require a highly reliable transport mechanism. With SureStream added to the IP network, the FM link benefits from “always on redundancy” without adding further link latency.
  • Overmodulation Cancellation
    A unique feature of the APT MPX Codecs is the cancellation of undesired peaks and drops of the MPX signal in order to reliably prevent overmodulation. Artefacts of this type are caused by lost packets during transmission.
  • ScriptEasy enabled on MPX Codecs
    With ScriptEasy, an MPX Codec can autonomously manage backup switching on MPX inputs and perform a wide range of other controls and actions.
APT codecs MPX card rear

SureStream for Broadcast Quality Audio over IP

SureStream technology is a revolutionary innovation from APT that enables broadcasters to use inexpensive IP links and still maintain professional broadcast-grade audio quality and reliability.

It delivers the audio quality and reliability you expect from a T1/E1 link at a fraction of the associated cost. APT SureStream Technology also offers the added benefit of «Always-On Redundancy». With APT SureStream Technology, you can save thousands on your audio transport bills and still offer your listeners the highest quality sound. 

 Learn more about

Connect with WorldCast Manager

The WorldCast Manager  simplifies the management of all SNMP-enabled devices in a network, providing real-time status, historical data and visualization of multiple devices from a single screen. The intuitive and simple-to-use interface shows all devices located at your site(s) displaying product information, alerting you to any alarms and providing one-click access to the unit’s web-based control interface.

The WorldCast Manager is compatible with all WorldCast Systems’ equipment as well as SNMP devices from ANY manufacturer.

logo WorldCast Manager

Learn more about
WorldCast Manager


Contribution and Distribution

APT IP CODEC application Time aligned content playout with NTP timing

MPX over IP 

Supporting MPX over IP

The APT AoIP Codec Module is also able to support 85kHz or 64kHz  of audio bandwidth and scale the sample rate to 192kHz or 128kHz, enabling a digital MPX signal to be sent on an AES stream. The output of the audio codec can therefore be transferred directly to the modulator of the exciter. This 100% digital path eliminates D/A and A/D conversions which may cause degradation of signal quality and could introduce distortion.

For maximum compatibility with existing analog MPX equipment, the AoIP card provides support for both Analog and Digital MPX transmission. Offering analog-analog, analog-digital and digital-digital MPX distribution all on a single platform provides broadcasters with a solution for their current needs and a clear and affordable migration path for the future.

user report

User report

«With the Multi-channel AoIP Codec, we have a reliable, scalable platform that delivers high-quality audio. And, most importantly, with SureStream, we have a simple, convenient solution that requires very little configuration and supervision and maintains the consistency of our audio quality output, even in the most intolerable network conditions.»
Jordi Gol,  Group Director of Technology,  Grupo Flaix, Catalonia, Spain

user report

User report

"The use of Digital MPX is helping Rice University make significant savings by reducing the manpower required to maintain the plant."
Rob Meuser, CTO, Engineaux Inc, USA 


Current Version: 3.0

APT AoIP Multichannel Codec
EthernetDual physical Ethernet ports, RJ45 for management and streaming
Virtual NetworkVirtual Interfaces and VLAN tagging
Analog I/OElectronically balanced, capacitive isolated on 37 pin D-Type connector#2) Imp. Hi/Lo and 600 Ω
Digital Audio I/OAES-3, 24 Bit, transformer balanced, on 37 pin D-Type connector#2 Imp. 110 Ω
Digital Ref InputAES, transformer balanced, on 37 pin D-Type connector#2, Imp. 110 Ω
Serial Aux Data and GPIO15 pin HD-Type, 2x serial on RS232 level, 4x opto-coupled inputs and relay contacts
ManagementWeb GUI, APT NMS, SNMP, XML API (available with a later release)
Asymmetric  AudioIndependent audio modes for sent and receive, independent clock domains
Audio ModesSimplex:  2x stereo Input or 2x stereo output ; Duplex: 1x stereo Input and Output
Digital Operation

Output FS, 32/44.1/48/96/192* kHz – software configurable

Audio Bandwidth10Hz to 20kHz mono & stereo 85kHz for digital MPX over AES*
Standard Coding Algorithms

aptX Enhanced 16 & 24 Bit, Linear PCM 16 & 24 Bit, MPEG 1/2 Layer II, MPEG4: AAC-LC/LD/ELD, MPEG2/4: HE-AAC v1/v2

Coding Delaymin. 2ms on aptX Enhanced and higher depending on chosen algorithm 
Dynamic Range16 Bit  >85dB,  24 Bit  >110dB
Network and IP
IP Protocols SupportedRTP/UDP/IP, RTCP, DNS, Dynamic DNS, DHCP, ICMP, IGMP, VLAN#, UPnP (IGD), NTP, SNMP, SMTP, HTTPS (management)
IP StatisticsComplete IP Statistics for each stream 
Casting ModesUnicast, multiple unicast, multicast, multi- multicast
De-Jitter BufferBuffer size 1 - 5,000ms adjustable, automatic packets re-sequencer 
RTP/UPD Streaming and ModesMultiple Tx-Streams, 2x Rx Streams, UDP stream forwarding, Auto-Detection of received Stream, Auto-Reply to sender
Quality of ServiceDiffServ, with separate DSCP values per stream, SureStream Technology and Error Concealment
Backup FeaturesSD Card for audio file storage
Network SecurityService Filter and Firewall Features
Serial Data Rates (embedded)11200, 2400, 4800, 9600 Baud (2 channels per AoIP module)
Serial Data Rates via IP1200 - 115,200 Baud (2 channels per AoIP module)
AUX Data via UDPUDP forwarding PAD or private Data
GPIO4 switch inputs, 4 relays; GPI transmitted as separate UDP stream or embedded in aptX Enhanced
Physical specification
19”  1U Dimensions (H / W / L)44mm x 482mm x 370mm 1.75” x 19” x 14.5”
Weight5Kg / 11lbs
Dual Power Supply

90-250 VAC / 47-60 Hz or 36-72VDC, AC/AC, AC/DC, DC/DC (order options)

Power Consumption< 60W
Guaranteed Working Temperatures0°C - +45°C
HumidityUp to 95% relative humidity (non-condensing)

* Cost option
#2with XLR breakout cable

Order information

STP00034+ SPP000484HP AoIP Module for APT Codec Frame 1U with XLR-Breakout Cable
SPP00049AUX/GPIO Breakout Cable for AoIP Module
Software Options
CD00136SureStream option for AoIP Module – 4HP
LC00074Digital MPX over IP option for APT Codecs
Codec Options
TFP0109-A0APT Codec Frame with AC/AC PSU
TFP0109-A1APT Codec Frame with DC/DC PSU
TFP0109-A2APT Codec Frame with AC/DC PSU



  • Watch the Webinar: How to Create your ULTIMATE IP Audio Network




    Published on Jun 22, 2017
  • APT SureStream technology

    Published on Feb 15, 2017
  • AUDEMAT ScriptEasy

    Published on May 30, 2017

Quick Start Guides


    Published on Jun 30, 2016



    Published on May 25, 2018
  • APT Frame - Hardware Manual

    Published on Dec 5, 2017
  • ScriptEasy - Manual

    Published on Mar 22, 2018


  • WorldNet NMS Software

    Published on Nov 5, 2018


  • WorldCast Systems Overview

    Published on Nov 15, 2018
  • The Essential Guide To Audio Over IP for Broadcasters

    Published on Feb 22, 2018

Press Kit

  • WorldCast Systems Logo - Press Kit

    Published on Feb 16, 2017
  • APT Multichannel AoIP Codec - Press Kit

    Published on Feb 16, 2017