Global IP Solutions (GIPS—aka ‘the folks who brought you the sound of Skype’) this week released a new white paper entitled How to Select the Best Codec for HD Voice, which looks at the growing demand in the marketplace for higher sound fidelity in everything from broadcast television to IP communications—and, as a result, the increasing interest in ‘high definition’ (HD) or ‘wideband’ voice.
The white paper examines the strengths of the company’s iSAC codec (def.)in comparison with other wideband codecs, and discusses the importance of subjective listening tests in evaluating audio quality.
Company chief researcher Jan Skoglund says the simple fact that GIPS’ iSAC codec supports 8 kHz serves as a key differentiator. “When you compare that to the other standard codecs out there, as we did in the listening test, people recognized that as getting higher fidelity and a crisper sound,” he says.
Still, as Skoglund notes, it’s not just about sound quality—the challenge lies in increasing robustness as well as fidelity. “You can utilize the available bandwidth to do better coding in the sense of getting less packet loss and quality degradation… these networks have limits that we didn’t have before in the PSTN world, so you have to cover all bases, both in fidelity and robustness,” he says.
Understanding HD voice
Company marketing manager John Gallagher says the aim of the white paper is to reach further into the enterprise market. While GIPS’ wideband voice solutions are well established in the consumer space, he says, some education is still required in the enterprise. “We’re seeing a much stronger interest in the enterprise market, and so we wanted to educate people on something that GIPS has been very well known for,” he says.
And the term ‘HD voice,’ Gallagher says, simply makes more sense to most users than wideband voice. “Wideband is an engineering term, but what we’re trying to do is to get people to recognize that, [as] with the advent of HDTV, you can get better voice quality—and I think that’s easier for people to understand than calling it wideband voice,” he says.
IDC analyst Rebecca Swensen agrees. “Most consumers don’t understand the technology behind these solutions,” she says. “However, when they hear ‘HD,’ they know the quality is clearer… because of their understanding of HD in the context of home entertainment. I doubt many consumers would understand ‘wideband’ is synonymous.”
John Hermansen, GIPS’ senior director of product management, says the company’s biggest challenge often lies simply in getting people to try the technology. “The first time that people tried something like Skype or Google Talk that was using this wideband technology—or this HD voice technology—they realized what they had been missing: they realized what they had been subjected to with the PSTN,” he says.
Increasing fidelity
Without the higher end of the audio spectrum, Hermansen says, you inevitably get a less natural sound—and more importantly, you lose intelligibility, particularly in differentiating similar sounds like s and f. “Foreign accents also become much more difficult to understand when you’re limiting the audio bandwidth to only 3.5 kHz as the PSTN does,” he says.
And Hermansen says the tradeoffs in leaving the PSTN are limited. “The more bandwidth and the more information you try to pack into those packets, there are other issues as far as delay and packet loss that you have to overcome—and we have other technology that we feel deals with that very well—but the overall end user fidelity experience is something that we feel is a real benefit of IP networks,” he says.
IDC’s Swensen says GIPS is positioned well in that regard. “One of the challenges GIPS has is that it has no control over the network… as such, their ability to control external forces is nominal,” she says. “However, they have developed the codec to handle such variables by including things such as dynamic bandwidth allocation. The overall effect is that the HD codec provides a quality, reliable experience.”
And as the white paper points out, it all comes down to each user’s subjective evaluation. “The most important part is the experience of the user,” Swensen says. “In these economic times, many are talking about cutting travel in order to save money. I imagine they still would like an experience similar to meeting with others face-to-face. HD voice offers a step closer to that experience in a remote environment.”
