SILK
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| Filename extension | .sil, .SIL |
|---|---|
| Internet media type | audio/SILK |
| Magic number | #!SILK\n |
| Initial release | March 2009 |
| Type of format | Audio |
| Extended to | Opus |
| Standard(s) | aktueller Standardentwurf |
| Website | developer.skype.com/silk |
SILK is an audio compression format and audio codec used by Skype. It is developed by Skype Limited. SILK is a replacement for the SVOPC codec.
The SILK codec was a separate development branch from SVOPC and it has been under development for over 3 years.[1] The stable version of SILK was first introduced in Skype 4.0 Beta 3 for Windows, released on January 7, 2009.[2] The final version of Skype 4.0 was released on February 3, 2009.[3][4] On March 3, 2009 Skype Limited announced that the SILK codec will be available soon under a royalty free license to third-party software and hardware developers.[5] To request the SILK binary SDK, one must send an email with some mandatory information, e.g. name, address, phone, description of how SILK will be used, etc.[6]
Skype Limited announced that SILK can use a sampling frequency of 8, 12, 16 or 24 kHz and a bit rate from 6 to 40 kbit/s. It can also use a low algorithmic delay of 25 ms (20 ms frame size + 5 ms look-ahead).[7]
The first draft of the SILK Speech Codec description was submitted to the IETF on July 6, 2009.[8] There is also a first draft of the RTP Payload Format and File Storage Format for SILK Speech and Audio Codec.[9] In September 2010 a draft of the Harmony codec which uses SILK and CELT was submitted to the IETF.[10] In October 2010, the Harmony codec was renamed to Opus.[11]
On March 22, 2011 the Steam game platform started using the SILK codec for its integrated in-game and community voice chat. Later in 14 April, in Team Fortress 2, the codec was implemented into the in-game voice chat.[12]
[edit] See also
[edit] Sources
- Stanford, M. - "Skype's new super-wideband codec"
- Skype Developer Information - "SILK – Super Wideband Audio Codec"
[edit] References
- ^ Michael Stanford (2009-01-13) Skype’s new super-wideband codec, Retrieved 2009-09-01
- ^ Skype Journal (2009-01-07) Skype for Windows 4.0 Beta 3 Hotfix Introduces New Audio Codec, Retrieved 2009-09-01
- ^ PCWorld (2009-02-04) Skype Upgrade Simplifies VoIP Video Calls, Retrieved 2009-09-01
- ^ (2009-02-04) Skype 4.0 audio: smooth as SILK, Retrieved 2009-09-01
- ^ Jonathan Christensen (2009-03-03) SILK, our super wideband audio codec, is now available for free, Retrieved 2009-09-01
- ^ Skype SILK – Super Wideband Audio Codec, Retrieved 2009-09-01
- ^ Skype SILK Data Sheet, Retrieved 2009-09-01
- ^ IETF (2009-07-06) SILK Speech Codec - draft-vos-silk-00.txt, Retrieved 2009-09-01
- ^ IETF (2009-07-06) RTP Payload Format and File Storage Format for SILK Speech and Audio Codec, Retrieved 2009-09-01
- ^ Definition of the Harmony Audio Codec
- ^ IETF "Harmony becomes Opus" announcement
- ^ http://www.teamfortress.com/hatless/
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