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Siren is a high-quality patented transform-based audio [[codec]] developed and licensed by [[Polycom]], Inc. There are three Siren codecs: Siren 7, Siren 14 and Siren 22.
Siren is a patented, transform-based, [[wideband audio|wideband]] [[audio codec]] developed and licensed by [[Polycom]], Inc. There are three Siren codecs: Siren 7, Siren 14 and Siren 22.


Siren 7 provides 7 kHz audio at [[bit rate]] of 16-32 kbps with [[sampling frequency]] 16 kHz. [[ITU-T]] [[G.722.1]] specification approved in 1999 is based on Siren 7, but provides only bit rates 24 and 32 kbps.<ref>(2008-08-05) [http://www.reuters.com/article/pressRelease/idUS135735+05-Aug-2008+MW20080805 Polycom Enables Acceleration of HD Voice Adoption by Offering Royalty-Free Codec], Retrieved 2009-09-07</ref><ref name="g7221-faq">{{cite web |author= |publisher=Polycom, Inc. |url=http://www.polycom.com/company/about_us/technology/siren_g7221/faq.html |title=Polycom Siren/G 722.1 FAQs |date= |accessdate=2009-09-07}}</ref> The algorithm of Siren 7 is identical to its successor, G.722.1, although the data formats are slightly different.
Siren 7 provides 7 kHz audio, [[bit rate]]s 16-32 kbps and [[sampling frequency]] 16 kHz. [[ITU-T]] [[G.722.1]] specification approved in 1999 is based on Siren 7, but provides only bit rate 24 kbps and 32 kbps.<ref>(2008-08-05) [http://www.reuters.com/article/pressRelease/idUS135735+05-Aug-2008+MW20080805 Polycom Enables Acceleration of HD Voice Adoption by Offering Royalty-Free Codec], Retrieved 2009-09-07</ref><ref name="g7221-faq">{{cite web |author= |publisher=Polycom, Inc. |url=http://www.polycom.com/company/about_us/technology/siren_g7221/faq.html |title=Polycom Siren/G 722.1 FAQs |date= |accessdate=2009-09-07}}</ref> The algorithm of Siren 7 is identical to its successor, G.722.1, although the data formats are slightly different.


Siren 14 provides 14 kHz audio at bitrate of 48/64/96 kbps with sampling frequency 32 kHz and supports stereo and mono audio. Siren 14 offers 40 millisecond algorithmic delay, using 20 millisecond frame lengths. The mono version of Siren 14 became ITU-T G.722.1C (14 kHz, 24/32/48 kbps) in April 2005.<ref name="g7221c">Polycom, Inc. (2005-04-12) [http://findarticles.com/p/articles/mi_m0EIN/is_2005_April_12/ai_n13600182/ ITU Approves Polycom Siren14 as New International Standard], Retrieved 2009-09-07</ref><ref name="g7221c-polycom">{{cite web |author= |publisher=Polycom, Inc. |url=http://www.polycom.com/company/about_us/technology/siren14_g7221c/index.html |title=Polycom Siren 14/G 722.1C |date= |accessdate=2009-09-07}}</ref>
Siren 14 provides 14 kHz audio, bit rates 48, 64, 96 kbps and sampling frequency 32 kHz. Siren 14 supports stereo and mono audio. It offers 40 millisecond algorithmic delay, using 20 millisecond frame lengths. The mono version of Siren 14 became ITU-T G.722.1C (14 kHz, 24/32/48 kbps) in April 2005.<ref name="g7221c">Polycom, Inc. (2005-04-12) [http://findarticles.com/p/articles/mi_m0EIN/is_2005_April_12/ai_n13600182/ ITU Approves Polycom Siren14 as New International Standard], Retrieved 2009-09-07</ref><ref name="g7221c-polycom">{{cite web |author= |publisher=Polycom, Inc. |url=http://www.polycom.com/company/about_us/technology/siren14_g7221c/index.html |title=Polycom Siren 14/G 722.1C |date= |accessdate=2009-09-07}}</ref>


Siren 22 provides 22 kHz audio with sampling frequency 48 kHz at 64/96/128 kbps stereo and 32/48/64 kbps mono. Siren 22 offers 40 millisecond algorithmic delay using 20 millisecond frame lengths. 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.<ref name="siren22-polycom">{{cite web |author= |publisher=Polycom, Inc. |url=http://www.polycom.com/company/about_us/technology/siren22/index.html |title=Polycom Siren 22 |date= |accessdate=2009-09-07}}</ref><ref name="g719-polycom">{{cite web |author= |publisher=Polycom, Inc. |url=http://www.polycom.com/global/documents/whitepapers/g719-the-first-itut-standard-for-full-band-audio.pdf |title=G.719: The First ITU-T Standard for Full-Band Audio |date=2009-04 |accessdate=2009-09-07}}</ref>
Siren 22 provides 22 kHz audio, sampling frequency 48 kHz, bit rates 64, 96, 128 kbps stereo and 32, 48, 64 kbps mono. Siren 22 offers 40 millisecond algorithmic delay using 20 millisecond frame lengths. 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.<ref name="siren22-polycom">{{cite web |author= |publisher=Polycom, Inc. |url=http://www.polycom.com/company/about_us/technology/siren22/index.html |title=Polycom Siren 22 |date= |accessdate=2009-09-07}}</ref><ref name="g719-polycom">{{cite web |author= |publisher=Polycom, Inc. |url=http://www.polycom.com/global/documents/whitepapers/g719-the-first-itut-standard-for-full-band-audio.pdf |title=G.719: The First ITU-T Standard for Full-Band Audio |date=2009-04 |accessdate=2009-09-07}}</ref>


== Software support ==
== Software support ==

Revision as of 16:21, 7 September 2009

Siren is a patented, transform-based, wideband audio codec developed and licensed by Polycom, Inc. There are three Siren codecs: Siren 7, Siren 14 and Siren 22.

Siren 7 provides 7 kHz audio, bit rates 16-32 kbps and sampling frequency 16 kHz. ITU-T G.722.1 specification approved in 1999 is based on Siren 7, but provides only bit rate 24 kbps and 32 kbps.[1][2] The algorithm of Siren 7 is identical to its successor, G.722.1, although the data formats are slightly different.

Siren 14 provides 14 kHz audio, bit rates 48, 64, 96 kbps and sampling frequency 32 kHz. Siren 14 supports stereo and mono audio. It offers 40 millisecond algorithmic delay, using 20 millisecond frame lengths. The mono version of Siren 14 became ITU-T G.722.1C (14 kHz, 24/32/48 kbps) in April 2005.[3][4]

Siren 22 provides 22 kHz audio, sampling frequency 48 kHz, bit rates 64, 96, 128 kbps stereo and 32, 48, 64 kbps mono. Siren 22 offers 40 millisecond algorithmic delay using 20 millisecond frame lengths. 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.[5][6]

Software support

Siren 7 is commonly used in videoconferencing systems and is also part of Microsoft Office Communicator when using A/V conferencing. In Windows XP, Siren 7 codec is implemented in %systemroot%\system32\SIRENACM.DLL.

Microsoft's Office Communication Server uses Siren during audio conferencing. With the default Officed Communicator client, point to point audio is by default performed using Microsoft's proprietary code RT-Audio. When a call is promoted into an audio conference (any time 3 or more participants have joined), the codec is switched on the fly to Siren. This is done for performance reasons.

FreeSWITCH communication open source software can do transcoding, conferencing and bridging of Siren 7-G.722.1 and Siren 14-G.722.1C audio formats.[7][8]

Licensing

Usage of Siren 7 and Siren 14 compressions require the licencing of patents from Polycom, in most countries. A royalty free licence for Siren 7 and Siren 14 is available from Polycom if certain fairly basic conditions are met.[8][9][10][11][2][12]

Usage of Siren 22 also require licencing of patents from Polycom.[11]

See also

References

  1. ^ (2008-08-05) Polycom Enables Acceleration of HD Voice Adoption by Offering Royalty-Free Codec, Retrieved 2009-09-07
  2. ^ a b "Polycom Siren/G 722.1 FAQs". Polycom, Inc. Retrieved 2009-09-07.
  3. ^ Polycom, Inc. (2005-04-12) ITU Approves Polycom Siren14 as New International Standard, Retrieved 2009-09-07
  4. ^ "Polycom Siren 14/G 722.1C". Polycom, Inc. Retrieved 2009-09-07.
  5. ^ "Polycom Siren 22". Polycom, Inc. Retrieved 2009-09-07.
  6. ^ "G.719: The First ITU-T Standard for Full-Band Audio" (PDF). Polycom, Inc. 2009-04. Retrieved 2009-09-07. {{cite web}}: Check date values in: |date= (help)
  7. ^ "FreeSWITCH First to Support Polycom's 32khz HD-Audio". FreeSWITCH. 2008-12-15. Retrieved 2009-09-07.
  8. ^ a b "libg722_1 - COPYING". FreeSWITCH. Retrieved 2009-09-07.
  9. ^ Xiph.Org Foundation (2009). "CELT - Codec Feature Comparison". Xiph.Org Foundation. Retrieved 2009-09-07.
  10. ^ Xiph.Org Foundation (2006). "Speex - Codec Quality Comparison". Xiph.Org Foundation. Retrieved 2009-09-07.
  11. ^ a b Polycom, Inc. Foundation. "Siren7/Siren14/G.719 License info". Polycom, Inc. Retrieved 2009-09-07.
  12. ^ Polycom, Inc. Foundation. "Polycom Siren 14/G 722.1C FAQs - What are the terms on the free license?". Polycom, Inc. Retrieved 2009-09-07.
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