Comrex Corporation | BRIC-Link

By: Comrex  09-12-2011

The Comrex BRIC-Link is a low-cost, high-performance solution for audio-to-IP conversion. Leveraging many of the core technical aspects of Comrex's successful remote broadcast ACCESS product line, BRIC-Link provides for an elegant way of moving linear or compressed audio with very low delay. BRIC-Link is very simple to use, and can be used over a wide range of IP links. While it carries an entry-level cost, BRIC-Link maintains superb audio specifications and hardware reliability, making the system suitable for STLs and other mission-critical functions without the expense required of more full-featured codecs.

BRIC-Link is contained in a small desktop package. Two BRIC-Links may be installed to occupy 1U of rack space.

BRIC-Link is uniquely suited to point-to-point "nailed up" high-quality audio links over a variety of data networks, such as:

  • ISM Band IP Radios
  • T1/E1
  • Satellite
  • WANs and LANs

The robustness of the BRIC technology (Broadcast Reliable Internet Codec) used in the box allows the system to perform well on the public Internet as well (using AAC compression modes).

Audio Coding

For users concerned about delay and coding artifacts, BRIC-Link offers a robust stereo or mono linear mode that does not compress audio. In addition, unique to real-time audio codecs, BRIC-Link offers FLAC lossless compression, reducing network throughput by 30-40% with absolutely transparent coding and no tandem coding concerns. For situations where more reduced bandwidth is desired, BRIC-Link offers AAC/HE-AAC modes as standard, allowing superb audio quality at dramatically reduced data rates.

Transmission Modes and Delay

BRIC-Link is a true codec, offering a full-duplex stereo encoder and decoder in each box. Where two-way transmission is not required, the reverse channel may be disabled. The BRIC technology incorporated includes a jitter buffer manager that automatically balances delay and stability, dynamically increasing delay based on network performance. For networks where the QoS is known these parameters may be set so that a consistent level of jitter buffer is maintained.

End-to-end coding delay in linear modes is less than 25ms and FLAC modes are less than 30ms. AAC modes incorporate around 100ms total end-to-end delay and HE-AAC modes deliver around 220ms.

In addition to coding delay, network propagation and jitter buffers will add delay to any IP link and are network dependent.

Connections & Indicators

BRIC-Link offers balanced, professional level analog I/O on 1/4" TRS connectors; a full set of 1/4" to XLR adapters are included. Alternately, the Left I/O connectors may be switched to AES3 digital audio format. Consumer level, 3.5mm unbalanced I/O is also available on the front panel. Network connection is via 10/100 BaseT Ethernet jack. Contact Closure and Ancillary data are delivered on Mini-DIN style jacks. Audio level is displayed on the front panel via L&R tri-color LEDs. These LEDs may be configured to display send or receive level. A status LED on the front panel displays connection status as well as Ethernet status.

User Interface

Initial IP configuration is managed via a Windows-based setup utility to be run on a computer located on the same LAN. The utility also functions as an upgrade utility, allowing flash upgrades from the Comrex website to be applied to the hardware.

Streaming Server Mode

BRIC-Link can function as a streaming server, delivering multiple streams to computer based media players that support HE-AAC (also known as aacPlus). HE-AAC has the advantage of delivering good quality at very low network bandwidth. As an example, BRIC-Link can deliver more than 40 stereo streams over a T1 Internet connection when using the HE-AACv2 24Kb/s encoder. Tested players include WinAmp, VLC and Windows Media Player with Orban/Coding Technologies aacPlus Plugin.

BRIC-Link also offers the ability to act as a source feed for both SHOUTcast and Icecast servers. With a single BRIC-Link, you can expand your radio presence to the Internet without the need for a dedicated PC.

Additional Features

BRIC-Link provides for four end-to-end contact closures to be delivered along with the audio stream in each direction. Alternately, the contact closure inputs may be configured to initiate connections. An ancillary data stream is available via RS232 along with the audio stream.

In AAC modes, the system is capable of sending multiple one-way encode streams to separate BRIC-Links or Comrex ACCESS codecs (requiring additional bandwidth). In addition, BRIC-Link supports IP Multicast on capable networks.

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