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Product Reviews
August 2002


Octiv, Inc.
2240 Sixth Street
Berkeley, CA 94710
Ph: 510-280-5000
Web site: www.octiv.com

Price: Software license; contact the company for specific pricing information.

Editor's Choice Award

Installation: 5
Documentation: 4
Features: 4.75
GUI: 4
Overall: A-

When people think of IP telephony, thoughts about latency and poor voice quality are often not far behind. Fortunately, VoIP has evolved considerably since its early days. Companies such as Octiv (www.octiv.com) and DiamondWare (www.diamondware.com) are working hard to reduce latency, eliminate echo, and improve sound quality, which improves the VoIP experience.

Octiv sells a developer�s toolkit called OctiVox that includes APIs (including DLLs) for performing audio processing to provide intelligibility enhancement (clarity) and echo mitigation. Its intelligibility enhancement function features the ability to enhance conference room situations where several voices are projected at the microphone from various distances and varying volume.

In addition, Octiv has partnered with DiamondWare to add DiamondWare�s latency reduction algorithms into OctiVox for a comprehensive �enhanced quality of experience� VoIP solution. Without getting into too many technical details, OctiVox takes shortcuts and eliminates unnecessary processing by optimizing the time it takes to access the underlying audio hardware/driver subsystem. In fact, according to Octiv they�ve determined that Windows XP has 120ms latency roundtrip, which OctiVox is able to reduce to 50ms.

We tested OctiVox, which comes with DLLs, API headers and libraries, and sample programs. We installed their main sample program on two PCs � a Pentium 450MHz running Windows 2000, and a Pentium 1GHz running Windows XP. To eliminate all other causes of latency (such as network congestion) we put both machines on their own private network. Running OctiVox SoftPhone Demo on both machines, we initiated a call using the NetBios name, which resolved to the appropriate IP address. After accepting the call, we held a two-minute conversation to gauge the speech quality and the latency. Watching the other person�s lips from across the room and listening for the spoken word in the headset receiver we found that the latency was almost imperceptible to the human ear � it was that good! Next, we clicked on a button to turn off OctiVox�s enhancement techniques and we immediately noticed an increase in latency and the voice quality was not as three-dimensional or as warm as with OctiVox turned on. The voice quality seemed a bit hollow with OctiVox turned off.

So how does it work? OctiVox employs an aggressive buffer management system that reduces the roundtrip delay to as little as 50 milliseconds. In addition, OctiVox has a multi-band processor that performs several functions. First, it makes volume levels consistent using amplitude normalization that equalizes output from different sources to compensate for different microphone settings, user speech habits, and user distance from the microphone. Second, OctiVox uses noise gating to reduce apparent noise level, increasing speaker clarity in noisy environments. Third, OctiVox applies spectral balancing to give each speaker�s voice a more uniform shape and optimizes it to the most comfortable response characteristics for the human ear. The multi-band processor also utilizes source separation to discriminate between multiple user voices and applies individual enhancement processing to increase the ability to hear each user�s voice.

OctiVox also will synchronize input/output by detecting and correcting sample rate drift within the sound card. OctiVox eliminates near-end acoustic echoes caused by speaker-to-microphone coupling. In conference calls when multiple users talk simultaneously, OctiVox�s acoustic echo suppression techniques can also reduce acoustic echo experiences at the remote-end by users who do not have OctiVox. OctiVox also improves peak-to-average ratio and the signal-to-noise ratio as well as performing dynamic peak limiting. Interestingly enough, OctiVox can also perform consonant and vowel enhancement by using advanced time/frequency models of the speech process. Also, since not all languages are the same, OctiVox can be customized for different language characteristics.

Using CoolEdit Pro, we measured the time it took for the voice to transmit from one PC to another PC, out the second PC�s speakers and back into the microphone on the first PC. With Octiv turned �off� we calculated an average one-way latency of 360ms and with Octiv turned �on� we calculated 110ms. This was an improvement of 150ms or 41.6 percent. We then ran MSN Messenger to see how well this program performs compared to OctiVox and we calculated an average latency of 150ms, or 40ms (36.6 percent) slower than OctiVox.

We had some issues with a Plantronics USB headset we also tested. We encountered about a one second delay (latency) when receiving voice on the USB headset, but for some reason it was perfectly fine when transmitting. The remote end could hear the USB headset user with almost no latency. We asked Octiv about this and they said that the version we had didn�t have USB support yet but they said they are supporting USB microphones/headsets.

Two of the key ingredients to VoIP�s success are voice quality and minimal latency. OctiVox has done a superb job addressing both of these needs: TMC Labs was impressed with the improved voice quality and virtually imperceptible latency of the OctiVox product. Developers will certainly find OctiVox a perfect solution to develop VoIP soft phones able to rival traditional phones in quality.

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