The author is co-founder of Telos Alliance and Syndicate of Sounds.
A number of years ago, 2003 or so, Steve Church and I had an idea to enhance HD Radio for FM. To our ears, the HD system for FM lacked a “wow” factor, as the conventional HD signal sounded very similar to the FM-Stereo counterpart.
Just as HDTV offered an incredible advance in visual resolution, we felt the listener needed to experience something similar, with HD broadcast audio. Basically, provide a significant reason why HD Radio was the next step beyond FM-Stereo.
At that time, the record label/audio industry was in the midst of promoting a couple of newer audiophile formats: SACD (Super Audio CD) and DVD-A (DVD Audio). Both of them allowed higher sampling rates, as well as offering discrete, linear 5.1 surround sound.
Record labels began reissuing older catalog material in newly produced 5.1 surround sound. Most were of the rock and classical genre, along with some box sets of complete album catalogs of well-known artists.
We found this exciting for a few reasons, as we were able to hear incredible recordings, by favorite artists, in a whole new light. Also, we got an idea of how to enable this on FM radio.
The new HD Radio platform was still fairly new, and looking for a means to attract consumers of the new tech. As mentioned we felt there was not a significant sonic reason why a consumer would be drawn to this — until we heard music in surround.
We’ve been very fortunate to have maintained a strong business and collegial relationship with the crew at the Frauhofer Institute (FhG), in Germany. On account of this, we learned they had recently developed a new method to transport 5.1 surround within a coded audio environment. This is known as MPEG-Surround.
A simple description explains the usage of the left/right stereo channels for audio transport coding, and at the same time data reducing the surround cues, which are transported alongside the main stereo audio. Then, during the decoding process, the surround cues will properly assign and derive each of the surround channels accordingly. This method provides discrete 5.1 surround and operates within a coded environment platform. The surround cues require very little data, normally around 5 kbps.
Given the data rate of the HD Radio system, MPEG-Surround was the perfect fit for FM broadcast. Automotive listening is the perfect experience for this, and it would surely add the needed “wow” factor to HD Radio, or so we thought.
Telos, along with FhG, built an operating prototype of this system, complete with demonstrations inside a BMW automobile at a couple of NAB Shows in Las Vegas. Anyone who heard the demo was blown away.
So, what happened?
Two mitigating circumstances negatively impacted this innovative idea: the record labels were too quick to pull the plug on producing more surround content, and broadcasters were reluctant to invest in the infrastructure changed needed to add this transmission method to their facilities — even though the Telos Alliance made this all easy and affordable via their AoIP tech, which allows 5.1 surround to easily coexist with stereo signals.
The lack of content was quite possibly the biggest challenge. It would have been very confusing to consumers as to whether their reception was stereo of surround.
Given all that has been expressed here, there has always been a concept that intrigued me. Would it be possible to render discrete 5.1 surround from existing stereo material?
Relevance to radio
This idea is not new, and there have been various upmixing applications available, which will output a “surround” signal.
Most, if not all, of these render surround using some form of simulation, or trickery to generate the added sound field. Most of them employ time delay, phase manipulation, reverb or switching to derive surround.
My goal was to develop an upmixer algorithm that operates in real time, without any of the aforementioned gimmicks — find a linear method that preserves original production integrity and creates discrete surround.
After much research into managing sound fields, I was able to develop a method that creates discrete surround, as it expands the original stereo stage into discrete Left, Right, Center, Left-Surround, Right-Surround, and LFE (Low Frequency Enhancement) or sub-woofer for short.
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This method is now known as Déjà Vu and is marketed through Syndicate of Sounds. The accompanying image is a basic illustration.
The system has been vetted out by some of the biggest names in the recording industry: Gary Katz, Hugh Padgham, Frank Filipetti, Giles Martin and Jean-Michel Jarre to name a few. Each of them has provided the proverbial “thumbs up” to the tech.
So, how does this apply for streaming? Well, after all that background information provided here, it’s really very simple. All of the work done for the HD Radio application ports over 100% to streaming! After all, HD Radio is basically another streaming platform, except we’re not dealing with transmitters and receivers.
Instead of the need to rely on discrete produced 5.1 material, all we need is a great-sounding discrete upmixer for 5.1, and a transport mechanism, like MPEG-Surround, and we are good to go! For the consumer, just about any player app will automatically provide 5.1 surround if an MPEG-Surround signal is present. The players default to this now.
For the streaming installation, all that is needed is a transport codec that both employs the Déjà Vu upmixer and contains MPEG-Surround as a streaming selection. Basically, a stereo audio connection in, and the output is both stereo and surround, all neatly packaged in a standard streaming format.
For broadcasters who stream, this is an excellent way to add a truly amazing wow factor to your online signal, and it does not require any change to your existing infrastructure. Now all content can be presented in true discrete 5.1 surround.
As of early February, the Telos Alliance is finalizing a software update that will enable their streaming product to offer both the Déjà Vu upmixing function, coupled with MPEG-Surround for the transport stream.
Find out more about this topic at syndicateofsounds.com.
