Simply the most reliable, rock solid, guaranteed live audio over IP

... Will THE REAL STL-IP Please Stand Up

STL-IP for professional audio over IP networks and the Internet

IP STL (Studio Transmitter Link ove

  A u d i o T X  S T L - I P AudioTX STL-IP PLUS Plus  -  P r o d u c t   I n f o. . .

New for 2014, AudioTX STL-IP Plus AudioTX STL-IP PLUS  changes everything.

For nearly 10 years, a single product has led the field in reliable, low delay, transmission grade live audio over IP networks and the Internet. In that time, other manufacturers have launched countless products with fancy names and promises, upgrades and revisions... but the STL-IP has remained the choice of those who know. It just works.

STL-IP PLUS AudioTX STL-IP PLUS  is a game-changer. To say that 'the best just got better' would be a cliché. But it has, and hugely so.


The All NEW

with SureFlow
-- included as standard --

Rock-Solid Studio to Transmitter Links over ANY IP Network
including the Internet and an unbelievably low delay of just 5ms.

Forget 99.99%, this is AS CLOSE TO 100% RELIABILITY AS IT GETS!

AudioTX STL-IP Plus Advanced IP Codec for MPLS, DSL, Internet, 3G/4G delivers live audio over IP networks with transmission grade audio quality & robustness and an extremely low delay of just 5ms!  Get unbelievable reliability even over the Internet with the unique SureFlowredundant multiple audio streams for reliable audio over internet included as standard - up to 5 redundant streams, any of which can be different bitrates and audio coding types, and also fallback on a host of additional backup audio options.  A single unit can encode your audio in 6 different ways/bitrates and send a total of up to 66 separate unicast/multicast copies of your audio. 

AudioTX STL –IP works with linear (uncompressed) audio at up to 24 bits and 96kHz sample rate, MPEG4 AAC*, AAC Low Delay* and HE-AAC (SBR)*, Enhanced APTx at 16 and 24 bits**, pro-quality OPUS and FLAC (lossless), professional grade MPEG Layer 2 and Layer 3 compression, J.41, G.722 and ADPCM.  Optional Forward Error Correction (FEC), a jitter buffer of up to 60 seconds plus synchronous transmission of serial ancillary data and/or contact closures (GPIO) make AudioTX STL-IP Plus Advanced IP Codec for MPLS, DSL, Internet, 3G/4G an incredibly flexible and cost-effective solution.

Incredible Audio Quality

Here's the most important bit: AudioTX STL-IP Plus Advanced IP Codec for MPLS, DSL, Internet, 3G/4G offers premium grade audio at any bitrate. You'll be surprised at how much and how obviously better the same coding algorithm or audio type sounds on STL-IP Plus Advanced IP Codec for MPLS, DSL, Internet, 3G/4G when compared to other manufacturers' products. STL-IP Plus just sounds better. There are no 'off-the-shelf' or consumer grade encoders in STL-IP; instead every one is a true professional quality, transmission grade encoder, tweaked to perfection so we're as careful with your audio as we know you are yourself. A full range of sample rates and bit depths are available - up to 24 bits per sample at a 96 kHz sample rate. And there's a selection of coding algorithms that is second to none. From full linear (uncompressed) PCM audio, through fully lossless coding with up to a 60% reduction in bitrates, adding near-lossless coding choices like J.41 and our own DAT12, plus highly efficient MPEG4 AAC, AAC Low Delay and HE-AAC encoding, the newest and the highest quality implementation of OPUS available today, Enhanced APTx coding, MPEG Layer 2 and Layer 3, G.722 and other ADPCM options.

Transmission Grade Reliability -  SureFlow

SureFlow is the most advanced and complete technology of its type and is exclusive to AudioTX STL-IP Plus 

When other manufacturers talk of redundant streaming (or Sure-this, Smart-that etc), what they mean is that they encode the audio into packets as normal and then just send maybe a couple of copies of the same audio packets to your destination and then hope that at least one copy gets there. That's not what we'd call 'sure'... that's just 'hopefully'. When they talk about 'Smart' we think it's actually a bit 'dim'.

SureFlowredundant multiple audio streams for reliable audio over internet is very different. You can send up to 5 different streams over any number of networks or internet connections - one, two or even five. Each of these redundant and independent streams are exactly that... err, redundant and independent. For each stream, your audio is separately encoded using any audio coding type you like, at any bitrate you like. And, using STL-IP ’s unique Virtual Networks feature, each can be sent anywhere and anyway you like - over a single connection or over multiple different network or internet connections and routed as you choose - to make it’s own, entirely independent, way to its destination. At the far end, every packet received from every independent stream is independently decoded all the way back to clean, crystal-clear audio and STL-IP chooses the best available quality, of course acting according to your chosen stream priorities, seamlessly picking and choosing and fixing right down to each individual sample of audio. And if that isn’t “Sure” enough for you, you can add one of two types of FEC (Forward Error Connection) to as many of the five streams as you like, add a safety buffer that holds up to 60 seconds of audio for every stream and then even define multiple options for alternative backup audio. Perfect. We’re smiling and you will be too.

There's much more detailed information on SureFlow together with some practical, real-world, examples of use on the special pages of information available via the menus at the top of the page.

Backup for the backup?

OK, so we've told you about SureFlowredundant multiple audio streams for reliable audio over internet

Want some more backup options on top of this? You can setup STL-IP Plus  to fallback to get audio from another sending STL-IP unit. Or play audio from files stored on the unit (which can, of course, be updated remotely... remember that this is no ordinary IP codec, this is STL-IP!). Or receive audio from a web-stream on the internet. Or even just take audio from the device's analogue or digital audio inputs if you have external audio sources that you'd like to switch to instead.

How low did you say that delay was?

As low as 5ms complete end to end delay (that's 5 thousandths of a second). And that applies for many of the coding algorithms we offer.

For those that have longer coding delays by the nature of the algorithm, STL-IP has the absolute lowest delay for any given algorithm. For example, less than 6ms for our lossless coding, just 40ms for MPEG Layer 2, 45ms for AAC Low Delay, less than 10ms for Enhanced APTx, 20ms for Opus. Again, that's end to end - from the input of unit A to the output of unit B and in real world conditions. Don't be fooled by competitor units that quote 'algorithmic delay' instead of owning up to what their units actually deliver.

Our jitter buffers are designed to be run at zero on any reasonably good network... so that 5ms delay we quote is exactly that... 5ms. But you can select up to 60 seconds of delay on one that you know is poor or unreliable. Other products require or recommend that you set a 20ms, 30ms or even 60ms jitter buffer (for which read extra delay) even on a private network and much more on other networks and the internet.

STL-IP Plus AudioTX STL-IP PLUS  works for you... not the other way around!

We don't give you a long list of recommendations - like telling you to choose particular ISPs, buy expensive premium internet connections, not to allow your office PCs to use the same network, to use special routers or switches... of course some of these things might be worthwhile, but shouldn't your codec just be good enough to work with your network as it is. The real STL-IP works reliably on your existing networks whether dedicated or shared, small or large, wired or wireless, private or public (internet), premium or low cost.

We have been proudly providing professional solutions for live audio over IP and the internet to broadcasters since 2000 and the years of research and expertise we've built up shows in our products.

Customers who try products in the AudioTX STL-IP range for the first time after working with other IP codec products are normally amazed at how obviously better STL-IP is - for reliability, audio quality and low delay. The difference is not small or subtle.

The most complete featureset of any product - all included as standard

With STL-IP Plus   we've created simply the best live audio over IP product on the market. It's crammed full of powerful, sophisticated functionality that's exclusive to our products. And we want to share that with every customer so you can experience it all. Not through an options list where you pay extra for every last item. But a simple, fair pricing policy.

To put it simply, every bit of functionality, every feature is included as standard on every STL-IP Plus  unit.

That includes SureFlow with up to 5 independent, truly redundant diverse streams, a huge range of audio coding options from 24 bit 96 kHz linear audio through lossless and near-lossless choices and algorithms that work right down to 16kbps (and still sound amazing). It includes government grade audio encryption, delays as low as 5ms, a selectable jitter buffer of up to 60 seconds, the ability to send up to 66 separate copies of your audio, being able to encode and send your audio using up to 6 different coding algorithms/bitrates. Then there's 2 different grades of FEC (forward error correction), ancillary data in sync with your audio using an RS232 port and also 4 in 4 out GPIO, TCP/IP, UDP and UDP Multicast sending, and a full range of fallback and backup audio options.

There are only two things you have to choose (and pay for) if you want them and these are the AAC Codec Pack (which adds MPEG4-AAC or AAC-LC, AAC Low Delay and HE-AAC) and the APTx Codec Pack which adds Enhanced APTx coding. We offer these separately as not everybody needs them and they have a cost to us. So separating them out lowers the cost of STL-IP Plus . It's also worth saying that what we charge for these 2 choices is much less than other manufacturers.


Need to send and/or receive broacast quality audio over IP networks, with total resilience and a minimal transmission delay?

AudioTX STL-IP Plus  is the solution. STL-IP Plus  is absolutely unique.

AudioTX STL-IP Plus  is the only product of its kind that has been designed exclusively for broadcast and professional audio use and to offer the same low delay, high-quality audio and robustness that you'd get from a pair of copper wires!


The system is flexible, easy to set up and has a whole load of clever functionality, but put simply:

  • You plug one AudioTX STL-IP device into a power outlet and an ethernet jack at location A (not a dedicated network, just a standard ethernet network which may be used for other computers, servers and office functionality... it could even be the Internet.)
  • You connect another STL-IP unit at location B.
  • You get live single- or bi-directional audio between the two with just a 5ms delay.
  • It's reliable and it works.

In fact, you can send audio from one unit to many others. You can send uncompressed (Linear) audio at up to 24 bit, 96 kHz, or use professional quality MPEG L2/L3, FLAC, OPUS, J.41, DAT12, ADPCM or G.722 coding, Plus MPEG4 AAC, AAC Low-Delay and HE-AAC v2 from just 14kbps, Enhanced APTx and more. You can add Forward Error Correction, Safety buffers and even send RS-232 serial or TTL signals with your audio...



E x a m p l e  A p p l i c a t i o n s :

  • IP STL - Studio to Transmitter links (STL) over any IP Network: including Telco, Private/Dedicated, LAN/WAN, Wireless or Satellite, and the Internet.

  • Distribution of live or shared programming for radio stations and groups.

  • Permanent and ad-hoc broadcast quality audio connectivity between sites.

  • Multicast audio distribution over Telco networks, Satellite, LAN/WAN and all multicast capable networks .

  • Telco carrier-grade distribution of live audio signals (one or two way) via TCP/IP or UDP (including multicast) over IP networks.

  • Combine several networks of different types with differing levels of reliability/performance and differing capacities (bitrates) into one with near 100% reliability using SureFlow.



Executive summary -  AudioTX STL-IP 

  • Offers the same high quality, resilience and low delay as a pair of dedicated copper wires.
  • Allows you to send and receive broadcast quality professional audio over IP networks - from LAN/WAN and private networks, to leased lines, Telco/carrier provided circuits, Satellite, Microwave and other wireless networks, T1, E1, ATM and the Internet.
  • A solution that works reliably over all networks, whatever your choices at a given site - fast or slow, great and reliable or a bit variable, big or small... STL-IP will always help you find a way.

You can:

  • Connect two STL-IP Plus units over a network and get live, bi-directional, low delay audio. Combine more than one network using different bitrates and encoding for SureFlow/5.
  • Use one STL-IP Plus unit to transmit your audio to up to sixty-six different destinations (an unlimited number of remote units when using multicast).
  • Be sure your audio is robust -  STL-IP Plus recovers automatically from power/network failures as soon as mains/connectivity returns.
  • Get the highest quality audio - with linear connections at up to 24/96, or high quality compressed audio using professional-grade MPEG Layer 2, MPEG Layer 3, J.41, DAT12, ADPCM, G.722, FLAC, pro-grade OPUS or our extra Low-Bitrate speech codec. Plus MPEG4 AAC, AAC Low-Delay and HE-AAC v2 with the AAC Codec Pack for Stereo audio from just 14kbps! The APTx Codec Pack adds Enhanced APTx coding.
  • Send additional TTL signals via the GPIO interface, or ancillary RS-232 data, in perfect sync with your audio.

r IP Networks and Internet) with a low 5ms delay - AudioTX STL-IP

... Will the REAL STL-IP Please Stand Up

Copyright (C) MDOUK MMXIV
unauthorised reproduction of contents prohibited
Contact us:    tel. +44 (0)121 256 0200 (GMT)


quicklink STL-IP Plus live IP Codec for broadcast:   home   about STL-IP Plus   STL-IP Plus features/specifications   applications
SureFlow 5 about   SureFlow Compared   Hear the Difference, premium audio quality
quicklink STL-IP Classic:   STL-IP product info   STL-IP features/specifications   applications   sales info/contact
quicklink:   STL-IP-16 and STL-IP-8   models   features   examples

quicklink:   STL-IP Connect Software for reporters and reliable remote / outside broadcasts over Internet

quicklink:   Main website for audio over IP solutions
quicklink:   The AudioTX STL-IP Blog for all things audio over IP