Broadcast Applications

STL (studio transmitter link) connection

Barix Instreamer/Exstreamer products are used in countless installations worldwide to link radio studios to transmitter sites, an application commonly addressed by the term STL – studio transmitter link. Unlike others, the Barix audio devices use an IP network connection, be it a directed wireless connection or a DSL link, to link between the studio and the transmitter site.

Using realtime MP3 encoding, the achievable audio quality is excellent – “better than CD” quality, at a bit rate of 320 kbps max. in the highest quality settings. The compression rate can be increased and sample rate can be set lower so a typical “FM” stereo audio signal can easily be streamed over a 128 kbps line. An uncompressed audio stream in PCM 48 kHz stereo (1536 kbps) is also possible.

The Barix IP Audio products are standalone, hardware based devices which are easy to set up, low power (<6 W power consumption), based on extremely reliable, embedded technologies (non-PC architecture) and low cost. A typical STL link setup can be achieved with one Instreamer and Exstreamer or Exstreamer Digital at a total cost of approx. $700 (not including the DSL line or equipment, of course).

The Instreamer can serve up to 8 concurrent streams, so multiple transmitter sites can be connected using just one Instreamer. In addition to be useable as STL link equipment, the Instreamer can also serve to stream to an icecast/shoutcast server for internet radio applications, or provide a stream into an audio recording solution (a simple, but fully functional, free recording software is available from Barix).

Find more info in the chapter STL connection over Internet

Following is a comparision of different Barix audio streaming solutions/firmwares:

Application / feature comparision for Audio Streaming/Broadcasting Scenarios

Features	Instreamer FW	Streaming Client FW	ABCL RTP STL FW	ABCL Reflector FW
for product type:	Encoder	Decoder	Encoder & Decoder	Encoder & Decoder
Streaming Direction	send only	receive only	send + receive (FDx)	send + receive (unidirect.)
Streaming Protocols	RTP, BRTP, HTTP and others	RTP, BRTP, HTTP	RTP, BRTP	RTP
Audio formats	MP3, G.711, PCM (8-48kHz)	MP3, G.711, PCM (8-48kHz), AAC+, OGG Vorbis	MP3, G.711, PCM (8-48kHz)	MP3, G.711, PCM (8-48kHz)
Backup Stream URL	no	yes (2 Backup URLs)	no	no
USB Backup	no	yes	yes	yes
Audio Priority Port	no	yes	no	no
IO-Support	CTS + inputs	relay	input + relay	input + relay
Serial Tunnel	yes (TCP)	yes (TCP/UDP)	yes (TCP/UDP)	no
Display Support	no	yes	yes	yes
Monitoring Capabilities	web page, SNMP	web page, Barimon, SNMP, relay	web page, SNMP, relay, email	web page, relay, email (from server)
Command Port	yes (UDP, TCP, CGI, serial)	yes (UDP, TCP, CGI, serial)	no	no

| ^{Fdx = Full-Duplex , RTP = Real-time Transport Protocol , BRTP = Barix Real-time Transport Protocol}

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