G.722.1 is a licensed

royalty-free Royalty-free (RF) material subject to copyright or other intellectual property rights may be used without the need to pay royalties or license fees for each use, per each copy or volume sold or some time period of use or sales. Computer standard ...

ITU-T standard

audio codec An audio codec is a device or computer program capable of encoding or decoding a digital data stream (a codec) that encodes or decodes audio. In software, an audio codec is a computer program implementing an algorithm that compresses and decompres ...

providing high quality, moderate

bit rate In telecommunications and computing, bit rate (bitrate or as a variable ''R'') is the number of bits that are conveyed or processed per unit of time. The bit rate is expressed in the unit bit per second (symbol: bit/s), often in conjunction ...

(24 and 32 kbit/s)

wideband In communications, a system is wideband when the message bandwidth significantly exceeds the coherence bandwidth of the channel. Some communication links have such a high data rate that they are forced to use a wide bandwidth; other links ma ...

(50 Hz – 7 kHz audio bandwidth, 16 ksps (kilo- samples per second) audio coding. It is a partial implementation of

Siren Siren or sirens may refer to: Common meanings * Siren (alarm), a loud acoustic alarm used to alert people to emergencies * Siren (mythology), an enchanting but dangerous monster in Greek mythology Places * Siren (town), Wisconsin * Siren, Wiscon ...

audio coding format An audio coding format (or sometimes audio compression format) is a content representation format for storage or transmission of digital audio (such as in digital television, digital radio and in audio and video files). Examples of audio coding ...

(which offers bit rates 16, 24, 32 kbit/s) developed by PictureTel Corp. (now

Polycom Poly, formerly Polycom, a part of HP Inc., is an American multinational corporation that develops video, voice and content collaboration and communication technology. Polycom was co-founded in 1990 by Brian L Hinman and Jeffrey Rodman. In 2018 ...

, Inc.). Its official name is ''Low-complexity coding at 24 and 32 kbit/s for hands-free operation in systems with low frame loss''. It uses a

modified discrete cosine transform The modified discrete cosine transform (MDCT) is a transform based on the type-IV discrete cosine transform (DCT-IV), with the additional property of being lapped: it is designed to be performed on consecutive blocks of a larger dataset, where ...

(MDCT)

audio data compression In information theory, data compression, source coding, or bit-rate reduction is the process of encoding information using fewer bits than the original representation. Any particular compression is either lossy or lossless. Lossless compressi ...

algorithm. G.722.1 Annex C (or G.722.1C) is a low-complexity extension mode to G.722.1, which doubles the algorithm to permit 14 kHz audio bandwidth using a 32 kHz audio sample rate, at 24, 32, and 48 kbit/s. It is included in the official ITU-T Recommendation G.722.1. The name of this annex is ''Annex C – 14 kHz mode at 24, 32, and 48 kbit/s''. It is an implementation of the

mono Mono may refer to: Common meanings * Infectious mononucleosis, "the kissing disease" * Monaural, monophonic sound reproduction, often shortened to mono * Mono-, a numerical prefix representing anything single Music Performers * Mono (Japanes ...

version of

's Siren 14 audio coding format. G.722.1 is the successor to PT716plus developed by PictureTel Corp. (now Polycom, Inc.), which has been used in videoconferencing systems for many years. As ITU-T Recommendation G.722.1, it was approved on September 30, 1999 after a four-year selection process involving extensive testing. G.722.1/Annex C was approved by ITU-T on May 14, 2005. G.722.1 is a transform-based compressor that is optimized for both speech and music. The G.722.1 algorithm is based on

lapped transform In signal processing, a lapped transform is a type of linear discrete block transformation where the basis functions of the transformation overlap the block boundaries, yet the number of coefficients overall resulting from a series of overlapping b ...

technology, using a Modulated Lapped Transform (MLT), a type of MDCT. The computational complexity is quite low (5.5 floating-point MIPS) for an efficient high-quality compressor, and the algorithmic delay end-to-end is 40 ms. The numbering of the

ITU audio codecs is sometimes confusing. There are three principal codecs, which are unrelated, but all carrying the G.722 label. G.722 is the original 7 kHz codec, using

ADPCM Adaptive differential pulse-code modulation (ADPCM) is a variant of differential pulse-code modulation (DPCM) that varies the size of the quantization step, to allow further reduction of the required data bandwidth for a given signal-to-noise ratio ...

and operating at 48–64 kbit/s. G.722.1, another 7 kHz codec, operates at half the data rate while delivering comparable or better quality than G.722, but is a transform-based codec. G.722.1 Annex C is very similar to G.722.1, but provides twice the audio bandwidth, 14 kHz. And G.722.2, which operates on

speech and delivers very low bitrates, is an

ACELP Algebraic code-excited linear prediction (ACELP) is a speech coding algorithm in which a limited set of pulses is distributed as excitation to a linear prediction filter. It is a linear predictive coding (LPC) algorithm that is based on the cod ...

-based algorithm.

Licensing

G.722.1 is available under a royalty-free license by Polycom Corporation, who owns all rights. Licensees also receive the right to use Polycom's 16 kbit/s decoder extension of G.722.1, as well as G.722.1 Annex C, and Polycom's IP within the new 20 kHz ITU fullband codec, G.719.

References

External links

* – technical specification * – RTP Payload Format for ITU-T Recommendation G.722.1 {{Compression formats Audio codecs Speech codecs Wideband codecs ITU-T recommendations ITU-T G Series Recommendations

Licensing

See also

References

External links