Polycom^® Siren^™ 22

The patented Polycom Siren 22 algorithm offers breakthrough benefits compared to earlier super wideband audio technology. The technology provides CD-quality audio for better clarity and less listener fatigue with audio and visual communication applications. Siren 22 advanced stereo capabilities make it ideal for acoustically tracking the speaker's movement in a telepresence room and help deliver an immersive experience.

Siren 22 requires dramatically less computing power and has much lower latency than alternative wideband audio technologies. To illustrate the quality Siren 22, we have compared it to another stereo codec - the popular MP3 (MPEG-1/2 Layer-3) audio codec used in portable music players.

The Polycom Siren 22 algorithm offers a number of advantages:

• Siren 22 stereo covers the acoustic frequency range up to 22 kHz while MP3 stops at 18 kHz. While the human ear usually does not hear above 18 kHz, the higher upper limit in Siren 22 delivers additional an audio dynamic that is especially important for music.

• Siren 22 requires less than 15 WMOPS (Weighted Million Operations Per Second) for encoder + decoder operation, compared to 100-200 WMOPS for competing algorithms. For example, MP3 requires 100 WMOPS.
• Therefore, Siren 22 can be used with lower-cost processors that consume less battery power, for example, in PDAs, mobile phones, or even wristwatches.

• Siren 22 offers 40 millisecond algorithmic delay using 20 millisecond frame lengths. This is the lowest latency of any super-wideband codec, and leads to more natural and spontaneous real-time communication. In comparison, MP3 has an algorithmic delay of 54ms at sample rate of 48 kHz and delay of 81ms at 32 kHz sample rate.

• Siren 22 handles speech, music, and natural sounds with equal ease. Most competing codecs are designed for voice and break up when presented with natural sounds or music.

• Siren 22 Stereo requires relatively low bit rates of 64, 96, or 128 kbps. This leaves more bandwidth available for improved video quality. In comparison, MP3 requires bit rates above 128kbps for comparable quality.

In May 2008, ITU-T approved the new G.719 full-band codec which is based on Polycom Siren 22 audio technology and Ericsson’s advanced audio techniques. The G.719 number gives this codec much higher visibility, and signifies the importance of the embedded technology. In its decision, ITU-T cited the strong and increasing demand for audio coding that provides the full human auditory bandwidth:

• Conferencing systems are increasingly used for more elaborate presentations, often including music and sound effects which occupy a wider audio bandwidth than that of speech
• In today’s multimedia enriched presentations, playback of audio and video from DVDs and PCs is becoming a common practice
• New telepresence systems provide high definition video and audio quality to the user, and require high-quality media delivery to create the immersive experience
• Extending the quality of remote meetings helps reduce travel which in turn reduces greenhouse gas emission and limits climate change