Internet Low Bitrate Codec

{{short description|Audio coding format}}

{{Infobox file format

|name = Internet Low Bit Rate Codec (iLBC)

|icon =

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|extension = .lbc{{cite web |url=http://tools.ietf.org/html/rfc3952 |title=Real-time Transport Protocol (RTP) Payload Format for internet Low Bit Rate Codec (iLBC) Speech |year=2004 |access-date=2011-06-23 |last1=Duric |first1=Alan |last2=Andersen |first2=Soren Vang }}

|mime = audio/iLBC

|type code =

|uniform type =

|magic = '#!iLBC30\n' or '#!iLBC20\n'

|owner = Global IP Solutions, now Google Inc

|released = {{Start date|2004|df=yes}}

|latest release version =

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|genre = Audio compression format

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|standard = RFC 3951

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}}

{{Infobox software

| name = iLBC Speech Coder

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| developer = Global IP Solutions, now Google Inc

| released = 2004

| programming language = C

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| genre = Audio codec, reference implementation

| license = 3-clause BSD

| website = [https://webrtc.org/license/ilbc-freeware https://webrtc.org/license/ilbc-freeware]

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| operating_system = Cross-platform

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Internet Low Bitrate Codec (iLBC) is a royalty-free narrowband speech audio coding format and an open-source reference implementation (codec), developed by Global IP Solutions (GIPS) formerly Global IP Sound (acquired by Google Inc in 2011{{cite web |url=http://www.zdnet.com/blog/open-source/why-google-bought-global-ip-solutions/6501 |archive-url=https://web.archive.org/web/20100521163742/http://www.zdnet.com/blog/open-source/why-google-bought-global-ip-solutions/6501 |url-status=dead |archive-date=May 21, 2010 |title=Why Google bought Global IP Solutions |author=Dana Blankenhorn |website=ZDNet |date=2010-05-18 |access-date=2011-06-23}}). It was formerly freeware with limitations on commercial use,{{cite web|url=http://www.ilbcfreeware.org/documentation/gips_iLBClicense.pdf |title=Global IP Solutions iLBC Freeware Public License |date=2008-10-30 |access-date=2011-06-23 |url-status=dead |archive-url=https://web.archive.org/web/20081030043137/http://www.ilbcfreeware.org/documentation/gips_iLBClicense.pdf |archive-date=October 30, 2008 }}{{cite web|url=http://www.ilbcfreeware.org/ |title=iLBCfreeware |url-status=dead |archive-url=https://web.archive.org/web/20081219092331/http://www.ilbcfreeware.org/ |archive-date=December 19, 2008 }} but since 2011 it is available under a free software/open source (3-clause BSD license) license as a part of the open source WebRTC project.{{cite web |url=http://www.webrtc.org/ilbc-freeware |title=iLBC Freeware |access-date=2011-06-23 |url-status=dead |archive-url=https://web.archive.org/web/20110705082246/http://www.webrtc.org/ilbc-freeware |archive-date=2011-07-05 }} It is suitable for VoIP applications, streaming audio, archival and messaging. The algorithm is a version of block-independent linear predictive coding, with the choice of data frame lengths of 20 and 30 milliseconds. The encoded blocks have to be encapsulated in a suitable protocol for transport, usually the Real-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 by Gizmo5, WebRTC, Ekiga, Google Talk, Maemo Recorder (on the Nokia N800/N810), Polycom IP Phone, Cisco, QuteCom, Tuenti,{{Cite web|url=https://vimeo.com/109608566|title=Tuenti+WebRTC (Voip2day 2014)}} Yahoo! Messenger, Ooma{{citation | url= http://support.ooma.com/home/star-codes-on-your-ooma-device/ |title=Ooma * codes|date=12 May 2015 }} and many others.

iLBC was submitted to IETF in 2002{{citation |url=http://www.itu.int/itudoc/itu-t/workshop/converge/s6am-p4_pp7.ppt |title=Speech Coders - a VoIP perspective |author=Roar Hagen |access-date=2011-06-23}}{{cite web |url=http://tools.ietf.org/html/draft-andersen-ilbc-00 |title=Internet Low Bit Rate Codec - draft-andersen-ilbc-00.txt |year=2002 |access-date=2011-06-23 |last1=Duric |first1=Alan |last2=Andersen |first2=Steven C. }} and the final specification was published in 2004.