Editing Enhanced full rate

{{short description|Speech coding standard}}
'''Enhanced Full Rate''' or '''EFR''' or '''GSM-EFR''' or '''GSM 06.60''' is a [[Speech encoding|speech coding]] standard that was developed in order to improve the quality of [[GSM]].

Enhanced Full Rate was developed by [[Nokia]] and the [[Université de Sherbrooke]] (Canada). In 1995, [[ETSI]] selected the Enhanced Full Rate voice codec as the industry standard codec for GSM/DCS.<ref name="archive-nokia">{{cite web |author=Nokia |url=http://www.nokia.com/news/news_htmls/nmp_951104.html  |title=Nokia Sets Industry Standard with New Voice Codec |date=1995-11-04 |access-date=2009-09-20 |archive-url = https://web.archive.org/web/19961220013144/http://www.nokia.com/news/news_htmls/nmp_951104.html |archive-date = 1996-12-20}}</ref>

== Technology ==
The sampling rate is 8000 sample/s leading to a bit rate for the encoded bit stream of 12.2&nbsp;kbit/s. The coding scheme is the so-called [[Algebraic Code Excited Linear Prediction]] Coder (ACELP). The encoder is fed with data consisting of samples with a resolution of 13 bits left justified in a 16-bit word. The three least significant bits are set to 0. The decoder outputs data in the same format.<ref name="gsm0660">[http://webapp.etsi.org/workprogram/Report_WorkItem.asp?WKI_ID=10153 ETSI EN 300 726 V.8.0.1 (2000-11) - (GSM 06.60 version 8.0.1 Release 1999)], Retrieved on 2009-07-08</ref>

The Enhanced Full Rate (GSM 06.60) technical specification describes the detailed mapping between input blocks of 160 speech samples in 13-bit uniform [[Pulse-code modulation|PCM]] format to encoded blocks of 244 bits and from encoded blocks of 244 bits to output blocks of 160 reconstructed speech samples. It also specifies the conversion between [[A-law]] or [[μ-law]] (PCS 1900) 8-bit PCM and 13-bit uniform PCM. This part of specification also describes the codec down to the bit level, thus enabling the verification of compliance to the part to a high degree of confidence by use of a set of digital test sequences. These test sequences are described in GSM 06.54 and are available on disks.<ref name="gsm0660" />

This standard is defined in [[ETSI]] ETS 300 726 (GSM 06.60). The packing is specified in ETSI Technical Specification TS 101 318.<ref name="rfc3551">[http://tools.ietf.org/html/rfc3551#page-27 RFC 3551 - GSM-EFR (GSM 06.60)], Retrieved on 2009-07-08</ref>
ETSI has selected the Enhanced Full Rate voice codec as the industry standard codec for GSM/DCS in 1995. Enhanced Full Rate was also chosen as the industry standard in US market for PCS 1900 [[GSM frequency bands|GSM frequency band]].<ref name="archive-nokia" /><ref name="jutta">{{cite web |author=Jutta Degener |url=http://www.quut.com/gsm/#half |title=Half-rate GSM and EFR |year=1995 |access-date=2009-09-20}}</ref>

== Licensing and patent issues ==
The Enhanced Full Rate incorporate several patents. It uses the patented ACELP technology, which is licensed by the VoiceAge Corporation.<ref name="archive-licEFRGSM">{{cite web |author=VoiceAge Corporation |url=http://www.voiceage.com/licEFRGSM.php |title=Licensing - EFR-GSM |date=2007-10-14 |access-date=2009-09-20 |archive-url=https://web.archive.org/web/20071014162151/http://www.voiceage.com/licEFRGSM.php |archive-date=2007-10-14}}</ref><ref name="licEFRGSM">{{cite web |author=VoiceAge Corporation |publisher=VoiceAge Corporation |url=http://www.voiceage.com/licEFRGSM.php |title=Licensing - EFR-GSM |access-date=2009-09-20}}</ref><ref name="archive-voiceage-technologies">{{cite web |author=VoiceAge Corporation |url=http://www.voiceage.com/technologies.php |title=Codec Technologies |date=2007-10-13 |access-date=2009-09-20 |archive-url=https://web.archive.org/web/20071013162836/http://www.voiceage.com/technologies.php |archive-date=2007-10-13}}</ref><ref name="voiceage-technologies">{{cite web |author=VoiceAge Corporation |publisher=VoiceAge Corporation |url=http://www.voiceage.com/technologies.php |title=Codec Technologies |access-date=2009-09-20}}</ref>

Enhanced Full Rate was developed by Nokia and the Université de Sherbrooke (Canada).<ref name="archive-nokia" />

==See also==
* [[Half Rate]]
* [[Full Rate]]
* [[Adaptive Multi-Rate]] (AMR)
* [[Adaptive Multi-Rate Wideband]] (AMR-WB)
* [[Extended Adaptive Multi-Rate - Wideband]] (AMR-WB+)
* [[Comparison of audio coding formats]]

== References ==
{{reflist}}

==External links==
* [http://tools.ietf.org/html/rfc3551#page-27 RFC 3551] - GSM-EFR (GSM 06.60)
* [http://webapp.etsi.org/workprogram/Report_WorkItem.asp?WKI_ID=10153 ETS 300 726 (GSM 06.60)]
* [http://www.3gpp.org/ftp/Specs/html-info/0660.htm 3GPP TS06.60] - technical specification
* [http://www.radio-electronics.com/info/cellulartelecomms/gsm_technical/audio-codecs-vocoders-amr-celp.php Summary of GSM Codecs]

{{Compression formats}}

[[Category:Audio codecs]]
[[Category:Speech codecs]]