Editing G.723.1

{{short description|ITU-T Recommendation}}
{{Infobox technology standard
| title             = G.723.1
| long_name         = Dual rate speech coder for multimedia communications transmitting at 5.3 and {{val|6.3|u=kbit/s}}
| image             = Pcm.svg 
| caption           = 
| status            = In force
| year_started      = 1996
| version           = (05/06)
| version_date      = May 2006
| preview           = 
| preview_date      = 
| organization      = [[ITU-T]]
| committee         = 
| base_standards    = [[G.721]]
| related_standards = [[G.726]]
| abbreviation      = 
| domain            = [[audio compression (data)|audio compression]]
| license           = Freely available 
| website           = https://www.itu.int/rec/T-REC-G.723.1
}}

'''G.723.1''' is an audio [[codec]] for voice that compresses voice audio in {{val|30|u=ms}} frames. An algorithmic look-ahead of {{val|7.5|u=ms}} duration means that total algorithmic delay is {{val|37.5|u=ms}}.<ref>{{Cite web|title=G.723.1: Dual rate speech coder for multimedia communications transmitting at 5.3 and 6.3 kbit/s|url=https://www.itu.int/rec/T-REC-G.723.1|url-status=live|archive-url=https://web.archive.org/web/20210613184127/https://www.itu.int/rec/T-REC-G.723.1|archive-date=2021-06-13|access-date=2021-06-13|website=www.itu.int}}</ref> Its official name is ''Dual rate speech coder for multimedia communications transmitting at 5.3 and {{val|6.3|u=kbit/s}}''. It is sometimes associated with a [[Truespeech]] trademark in coprocessors produced by [[DSP Group]].<ref name="dsp-ct8022">{{cite web|title=CT8022 VOIP/VON G.723.1, G729AB TRUESPEECH® CO-PROCESSOR|url=http://nic.ath.cx/PDF/computer/LinuxJack/CT8022.pdf|archive-url=https://web.archive.org/web/20180404222124/http://nic.ath.cx/PDF/computer/LinuxJack/CT8022.pdf|access-date=4 April 2018|archive-date=4 April 2018|quote=The CT8022 has built-in TrueSpeech 8.5 (compatible with Microsoft Sound System 2.0, and a standard part of Microsoft Windows 95), and TrueSpeech G.723.1 (for H.323 and H.324). [...] The CT8022 provides two additional non-ITU TrueSpeech data rates at 4.8 and 4.1 KBPS.}}</ref>

This is a completely different codec from [[G.723]].

There are two [[bit rate]]s at which G.723.1 can operate:
* {{val|6.3|u=kbit/s}} (using 24-byte frames) using a [[MPC-MLQ]] algorithm ([[Mean opinion score|MOS]] 3.9)
* {{val|5.3|u=kbit/s}} (using 20-byte frames) using an [[ACELP]] algorithm ([[Mean opinion score|MOS]] 3.62)

== Use ==
G.723.1 is mostly used in Voice over IP ([[VoIP]]) applications due to its low bandwidth requirement. Music or tones such as [[DTMF]] or [[fax]] tones cannot be transported reliably with this codec, and thus some other method such as [[G.711]] or [[out-of-band signaling|out-of-band]] methods should be used to transport these signals. The complexity of the algorithm is below 16 MIPS. 2.2 kilobytes of RAM is needed for codebooks.

G.723.1 is a required audio codec in the [[H.324]] ITU-T recommendation for H.324 terminals offering audio communication. In [[3GPP]] [[3G-324M]] specification support for G.723.1 is not mandatory, but recommended.

== Features ==
* Sampling frequency {{val|8|u=kHz}}/16-bit (240 samples for {{val|30|u=ms}} frames)
* Fixed bit rate ({{val|5.3|u=kbit/s}} with 20 byte {{val|30|u=ms}} frames, {{val|6.3|u=kbit/s}} with 24 byte {{val|30|u=ms}} frames)
* Fixed frame size for each rate ({{val|5.3|u=kbit/s}} with 20 byte {{val|30|u=ms}} frames, {{val|6.3|u=kbit/s}} with 24 byte {{val|30|u=ms}} frames)
* Algorithmic delay is {{val|37.5|u=ms}} per frame, with {{val|7.5|u=ms}} look-ahead delay
* G.723.1 is a hybrid speech coder, with high bit rate using multi-pulse maximum likelihood quantization (MP-MLQ) and low bit rate using algebraic code-excited linear prediction (ACELP)
* The complexity of the algorithm is rated at 25, using a relative scale where [[G.711]] is 1 and [[G.729a]] is 15.
* G.723.1 Annex A defines 4 byte silence insertion descriptor (SID) frame for [[Comfort noise|Comfort Noise Generation]]
* [[PSQM]] testing under ideal conditions yields [[mean opinion score]]s of 4.08 for G.723.1 ({{val|6.3|u=kbit/s}}), compared to 4.45 for [[G.711]] ([[μ-law]])
* PSQM testing under network stress yields [[mean opinion score]]s of 3.57 for G.723.1 ({{val|6.3|u=kbit/s}}), compared to 4.13 for [[G.711]] ([[μ-law]])

== Licensing ==
As of January 1, 2017, the [[patent term]]s of most patents applying to G.723.1 have expired. With regard to the unexpired licensed patents of their G.723.1 patent license agreement, the licensors of G.723.1 patents, namely AudioCodes, Orange SA, and Université de Sherbrooke have agreed to license their patents under the existing terms on a royalty-free basis starting January 1, 2017.<ref>{{Cite web|url=http://www.sipro.com/G723-1.html|title=SiproLAB Telecom - patent pool creation and management for standardized telecommunication technologies|date=2017-12-22|archive-url=https://web.archive.org/web/20171222150241/http://www.sipro.com/G723-1.html|access-date=2018-01-10|archive-date=2017-12-22}}</ref>

The authorized [[intellectual property rights]] licensing administrator for G.723.1 technology is Sipro Lab Telecom.<ref name="sipro">{{cite web|author=VoiceAge Corporation |url=http://www.voiceage.com/licg7231.php |title=G.723.1 Licensing |date=2007-10-14 |access-date=2009-09-17 |archive-url=https://web.archive.org/web/20071014161510/http://www.voiceage.com/licg7231.php |archive-date=2007-10-14 |url-status=dead }}</ref><ref name="siprolab-faq">{{cite web|author=Sipro Lab Telecom |url=http://www.sipro.com/faq.php |title=FAQ G.729 and G.723.1 |date=2007-10-25 |access-date=2009-09-17 |archive-url=https://web.archive.org/web/20071025051836/http://www.sipro.com/faq.php |archive-date=2007-10-25 |url-status=dead }}</ref><ref name="siprolab-g723">{{cite web|author=Sipro Lab Telecom |url=http://www.sipro.com/g7231.php |title=G.723.1, the highest ITU-T compression ratio |date=2006-10-29 |access-date=2009-09-17 |archive-url=https://web.archive.org/web/20061029005629/http://www.sipro.com/g7231.php |archive-date=2006-10-29 |url-status=dead }}</ref>

Members of the G.723.1 [[patent pool]] are [[AudioCodes]], [[France Telecom]], [[Université de Sherbrooke]], [[Nippon Telegraph and Telephone Corporation]] and [[Nokia]].<ref name="siprolab-g723-patentpool">{{cite web|author=Sipro Lab Telecom |url=http://www.sipro.com/g723members.php |title=G.723.1 - Members |date=2006-10-29 |access-date=2009-09-17 |archive-url=https://web.archive.org/web/20061029005826/http://www.sipro.com/g723members.php |archive-date=2006-10-29 |url-status=dead }}</ref>

== See also ==
* [[List of codecs]]
* [[Comparison of audio coding formats]]
* [[RTP audio video profile]]

== References ==
{{Reflist}}

== External links ==
* [http://www.itu.int/rec/T-REC-G.723.1 ITU-T Recommendation G.723.1] - technical specification
* [http://www.itu.int/ITU-T/ipr/index.html Intellectual Property Rights] page on ITU website (with link to patent declaration database)

{{Compression formats}}
{{Authority control}}

[[Category:Audio codecs]]
[[Category:Speech codecs]]
[[Category:ITU-T recommendations]]
[[Category:ITU-T G Series Recommendations]]