| Internet Low Bit Rate Codec (iLBC) | |
|---|---|
| Filename extension | .lbc[1] |
| Internet media type | audio/iLBC[1] |
| Magic number | '#!iLBC30\n' or '#!iLBC20\n'[1] |
| Developed by | Global IP Solutions, nowGoogle Inc |
| Initial release | 2004 (2004)[1] |
| Type of format | Audio compression format |
| Standard | RFC 3951 |
| iLBC Speech Coder | |
|---|---|
| Developer(s) | Global IP Solutions, nowGoogle Inc |
| Initial release | 2004 |
| Written in | C |
| Operating system | Cross-platform |
| Type | Audio codec,reference implementation |
| License | 3-clause BSD |
| Website | https://webrtc.org/license/ilbc-freeware |
Internet Low Bitrate Codec (iLBC) is aroyalty-freenarrowbandspeechaudio coding format and anopen-sourcereference implementation (codec), developed byGlobal IP Solutions (GIPS) formerly Global IP Sound (acquired byGoogle Inc in 2011[2]). It was formerlyfreeware with limitations on commercial use,[3][4] but since 2011 it is available under afree software/open source (3-clause BSD license) license as a part of the open sourceWebRTC project.[5] It is suitable forVoIP applications,streaming audio, archival and messaging. The algorithm is a version of block-independentlinear predictive coding, with the choice ofdata frame lengths of 20 and 30 milliseconds. The encoded blocks have to be encapsulated in a suitable protocol for transport, usually theReal-time Transport Protocol (RTP).
iLBC handles lost frames through graceful speech quality degradation. Lost frames often occur in connection with lost or delayed IP packets. Ordinary low-bitrate codecs exploit dependencies between speech frames, which cause errors to propagate when packets are lost or delayed. In contrast, iLBC-encoded speech frames are independent and so this problem will not occur.
iLBC is defined in RFC 3951. It is one of the codecs used byGizmo5,WebRTC,Ekiga,Google Talk,Maemo Recorder (on theNokia N800/N810),Polycom IP Phone,Cisco,QuteCom,Tuenti,[6]Yahoo! Messenger,Ooma[7] and many others.
iLBC was submitted to IETF in 2002[8][9] and the final specification was published in 2004.