Campbell: Trends in Codecs
     

Kevin Campbell
One year ago, Radio World asked several experts to discuss trends in the broadcast codec technology arena (Jan. 2, 2013). It was a popular topic, so we return to it now to learn more and find out what’s new in a set of four Q&As. Replies were via email and have been edited for length.

Here, Kevin Campbell, APAC/Americas APT Sales Director with WorldCast Systems, comments. Watch the website for the rest in the series.

What’s the most important recent development in codec technology?

Campbell: I think the most significant would be the recent adoption of a redundant streaming approach to counteract adverse network conditions on lossy IP links. This approach is enabling broadcasters to utilize cost-effective public Internet connections to replace or backup main connections without any loss of quality compared to the traditional (and substantially more expensive) synchronous connections such as T1. It has opened up a new path for audio broadcasters and gained in popularity.

APT pioneered this field when we launched SureStream technology back in 2010 and the past year has seen a rise in “CopyStream” technologies from competitors attempting to emulate its success and in some cases retrofit it to legacy hardware. We are confident that SureStream remains significantly ahead in terms of performance and sophistication and will continue maintain our market-leading position in this field. This is at least in part due to refinements and feedback from our significant installed base. In fact, 2013 saw the first large-scale telco deployment of the technology in a country-wide network with over 100 codec units which represents a landmark in the adoption of this approach.

It seems broadcast users should be well familiar with audio over IP, but there never seems to be enough information in the marketplace to meet the level of interest.

Campbell: There are still plenty of misperceptions and misinformation. The one that we still hear a lot is the fact that a link is declared free from packet drop after an engineer does a PING test. Just because a PING is completed is of little relevance in the IP codec world as the PING test operates using TCP/IP whilst the audio codec, primarily (through not exclusively) uses UDP/IP.

It’s these types of persistent misperceptions that have prompted us to rewrite our successful “Practical Guide to IP Audio.” We first released this primer back in 2008/9 near the start of the IP audio phenomenon and it soon became a must-read for engineers contemplating a migration to IP audio transport. We are updating the guide and plan to have the new version available before NAB 2014.

What relevance does the AES67 standard have?

Campbell: The advantages of the technology and the contributing technologies to the standard are well documented. It negates the need for punch blocks, patch panels and tons of cables in any facility and simply and elegantly replaces them with Cat-5 Ethernet cable and off-the-shelf switches. The sophistication of this solution combined with the flexibility that AES67 offers in terms of audio routing and the ease of connectivity to AES67 products makes it a “killer technology.”

Clearly as codecs are a key element in moving audio channels between facilities, the technology will have an impact on our range. Watch this space for what we do!

What is the “state of the art” in algorithms?

Campbell: At the risk of sounding like a broken record, you can’t really go past Enhanced apt-X if you are looking for a “no compromise” solution. No compromise in terms of audio fidelity and latency, the characteristics of the algorithm remain markedly close to Linear PCM and vastly superior to psychoacoustic algorithms, especially when it comes to multiple encodes or tandem coding. Enhanced apt-X is still being bought into globally by broadcasters, broadcast service providers and telcos, where quality and audio fidelity are the prime objective.

We have seen much less demand and, in some territories, very little awareness for the newer algorithms such as Opus. Licensing costs and availability of the algorithm quite often outweigh the inherent qualities of the algorithm in determining the market penetration, especially in our quite small niche sector where we purchase in the hundreds and the thousands rather than the millions like the consumer sector.

To generalize, I think the holy trinity for broadcasters could be stated as Enhanced apt-X, to be used where no compromise on quality, but bandwidth constraints; Linear PCM, to be used where there are no bandwidth constraints; and HE-AAC , to be used where the bandwidth is heavily constrained.

What is your newest product or feature?

Campbell: The latest addition to our core audio-over-IP codec range is the ScriptEasy remote control application. Known from our Audemat line of remote control devices, ScriptEasy has been integrated into APT codec units to deliver a unique way of offering advanced remote control, which would previously only have been possible using external devices.

Using powerful remote control logic, it endows the codec with inbuilt intelligence which can enable it to act how you wish it to when certain criteria are met in the internal performance metrics or from up to five external pieces of equipment. For example, you can trigger specific line backups based on packet loss experienced, you can switch schedule changes to receive local programming at specific times or days and you can implement a different audio profile should your main transmitter switch to the auxiliary.

These are just examples; the true power of the application is that it can do what you want it to do. … In the U.S. it is widely in use within the Clear Channel group as the technology used to remotely control and monitor all studio and transmitter sites throughout the country on the Relio hardware platform.

How does the decline in POTS, ISDN and other older services affect your users?

Campbell: This year we have had an announcement from Verizon in the northeast U.S. that no more new installations will be undertaken for ISDN. No one was shocked really; it’s to be expected as backbones continue to change and the support personnel who know anything about ISDN continue to dwindle. Those who have ISDN at studio and remote sites (ballparks, concert venues etc.) continue to have service, albeit sometimes degraded.

I regularly speak to many customers who want to make the transition to IP; however it’s the age-old problem of budget vs. necessity. The engineer believes it’s necessary to make the jump now, as ISDN is really on its last legs; however management won’t make the investment as the ISDN links have not yet been discontinued or no notice of discontinuation of the service has been issued. So we continue on a gradual phased transition as budgets become cyclically available.

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