Field Report: Barix Exstreamer 1000

August 1, 2010

Barix Exstreamer 1000

The Internet daily redefines the boundaries and applications of audio delivery. Point-to-point, point-to-multipoint, multipoint-to-multipoint - the combinations are endless. Add to that the job of transporting timely data and contact closures. The Barix Exstreamer 1000 encodes and decodes audio, data and closures over IP at an affordable price. It is easily configured and robust. The firmware fills a low-cost niche for flexible STL operation, program syndication or Internet streaming.

Zurich-based Barix supplies audio, data and control products for a variety of industries. Its IP interface devices transport audio and closures for program syndicators as well as two-way intercom and control for public address and security applications.

Whether your data path is LAN, WAN/VPN, Wi-Fi or DSL, the Exstreamer 1000 can get audio there using a modest amount of bandwidth. Data bandwidth requirements range from 50kb/s to 2Mb/s with latancy ranging from 20ms to 300ms depending on the compression scheme used.

The hardware layer

The Exstreamer 1000 can function as both an encoder or a decoder. It has both balanced analog and AES3 audio interfaces on DB9 connectors. Two data ports provide RS-232 (DB9) and RS-485 (Eurostyle) connections. There are four dry contact closures and a USB flash interface for local audio storage. The Exstreamer family of products are packaged in modular metal cases that can be rack-mounted or bracketed to a wall. It is powered by an external 24-48Vdc supply and uses very little power (about 8W).

Barix products are versatile and can be customized for specific applications like broadcast, public address and intercom/security. The Exstreamer can serve up high-quality stereo PCM linear streaming for broadcast transmission, or it can decode compressed audio streams and files such as MPEG-1 and 2, Layer 3 (MP3), A-law or µ-law with sample rates from 8kHz to 48kHz. It can stream audio continously as an STL or be modified instantly to store and forward audio from a playlist.

Performance at a glance
Stereo encode/decode
Supports MPEG-1 and 2 Layer 3 (MP3), PCM linear and A-law, µ-law
8-48kHz sample rate support
USB 1.1 interface for flash memory
Wide-range power supply input with low power consumption
AES3 and balanced analog stereo I/O
Two independent serial ports (RS-232 and RS-485)
Four contact closure inputs and four relay outputs

The software layer

The Audio Barix Control Language (ABCL, similar to BASIC language programming) offers a higher degree of control and customization. It can be used to monitor, switch audio sources or control audio levels. Sensing for silence, the ABCL program can switch to an alternate audio source on the Internet or play back audio stored locally on a USB drive.

A standard Internet browser is all that is needed to control and configure the codec. Pull-down menus display factory-designed applications, system settings, a reboot function and firmware updating.

The Web GUI Application menu displays the preprogrammed STL and store-and-forward operating modes germane to the Exstreamer 1000. Several other unique applications (not available on the Exstreamer 1000) are shown in the menu, including full-duplex audio, conference and Internet Speaker modes, which are applicable to other Barix products.

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Put into use

When configured as an STL, the Exstreamer 1000 acts as a high-quality audio streamer. The source can be mic or line level and either mono or stereo. Depending upon the application and available bandwidth, the user may choose to encode audio as PCM MSB, PCM LSB, µ-Law or A-Law. Sample rates range from 8kHz to 48kHz.

The data buffer provides some degree of smoothing for less dependable IP connections. Master volume, mic volume and A/D amplification controls are provided for fine tuning levels.

The audio storage and playback function uses a local USB thumb drive or memory stick for storage. A master text file created and stored on the memory stick directs the behavior of the unit. It defines the location where playlists and audio files can be downloaded. This text file also defines the details of playback or restricted playback (day parting), file updating and device monitoring. File transfer via HTTP, FTP and RTP (Real Time Protocol) are supported.

An extensive set of commands are available for customized control of audio playback, rotation, timing and volume levels. The Web browser can be used to make configuration changes on the fly and monitor current variables.

You might wonder if there are any known security vulnerabilities. The Exstreamer 1000 uses a proprietary kernel and TCP implementation called Cobos by Lantronix. It is built on the same source code as IP adapters (device servers), and it has been customized by Barix for further protection against certain DOS issues, making it appropriate for streaming applications. As an attack point, the functionality is very limited as opposed to a Linux or Windows system.

Out of the box

Basic functions like the STL mode are simple to configure and use. Advanced features such as the ABCL and FTP store/foward are a bit more esoteric but can be powerful tools once mastered. When powering for the first time, a human voice greets the user over the audio output port announcing the IP address of the unit. Customize the unit by recording and replacing the IP address announcement with your own voice.


The Barix website is replete with information on the device as well as sample configuration files. A wiki page provides additional topics beyond the manual. Technical support is currently limited to e-mail and/or long distance to Europe, but the fine folks in technical support are helpful and willing to be contacted via Skype should the need arise.

The reboot function was a very desirable feature; however, the device automatically reboots when changing between applications, thus there is a bit of a wait time before audio can be restored. Interestingly, Barix hosts a free service where one can remotely monitor the device for program delivery assurance. Should the IP connection drop, audio is restored within about a second once the connection is renewed.

Chestnut is assistant chief engineer at Entercom Kansas City.

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