Editing G.711 (section)

{{short description|ITU-T recommendation}}
{{Infobox technology standard
| title             = G.711
| long_name         = Pulse code modulation (PCM) of voice frequencies    
| image             = Pcm.svg 
| caption           = 
| status            = In force
| year_started      = 1972
| version           = (02/00)
| version_date      = February 2000
| preview           = 
| preview_date      = 
| organization      = [[ITU-T]]
| committee         = 
| base_standards    = 
| related_standards = [[G.191]], [[G.711.0]], [[G.711.1]], [[G.729]]
| abbreviation      = 
| domain            = [[audio compression (data)|audio compression]]
| license           = 
| website           = https://www.itu.int/rec/T-REC-G.711
}}
{{Floating-point}}

'''G.711''' is a [[narrowband]] [[audio codec]] originally designed for use in [[telephony]] that provides toll-quality audio at 64&nbsp;kbit/s. It is an [[ITU-T]] standard (Recommendation) for audio [[encoding]], titled '''Pulse code modulation (PCM) of voice frequencies''' released for use in 1972. 

G.711 passes audio signals in the [[frequency band]] of 300–3400&nbsp;Hz and [[Sampling rate|samples them at the rate of]] 8000&nbsp;Hz, with the tolerance on that rate of 50 [[parts per million]] (ppm).

It uses one of two different logarithmic [[companding]] algorithms: [[μ-law]], which is used primarily in North America and Japan, and [[A-law]], which is in use in most other countries outside North America. Each companded sample is quantized as 8 bits, resulting in a 64&nbsp;kbit/s [[bit rate]]. 

G.711 is a required standard in many technologies, such as in the [[H.320]] and [[H.323]] standards.<ref name=":0">{{Cite web|url=https://www.itu.int/rec/T-REC-G.711|title=G.711 : Pulse code modulation (PCM) of voice frequencies|website=www.itu.int|url-status=live|archive-url=https://web.archive.org/web/20190617130328/https://www.itu.int/rec/T-REC-G.711|archive-date=2019-06-17|access-date=2019-11-11}}</ref> It can also be used for [[fax]] communication over IP networks (as defined in [[T.38]] specification). 

Two enhancements to G.711 have been published: '''G.711.0''' utilizes [[lossless data compression]] to reduce the bandwidth usage and '''G.711.1''' increases audio quality by increasing bandwidth.