G.722.1
Encyclopedia
G.722.1 is a licensed royalty-free ITU-T standard audio codec
providing high quality, moderate bit rate
(24 and 32 kbit/s) wideband
(50 Hz - 7 kHz audio bandwidth, 16 ksps (kilo-samples
per second) audio coding. It is a partial implementation of Siren
7 codec (which offers bit rates 16, 24, 32 kbit/s) developed by PictureTel Corp. (now Polycom
, Inc.). Its official name is Low-complexity coding at 24 and 32 kbit/s for hands-free operation in systems with low frame loss.
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
version of Polycom
's Siren 14 codec.
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 transform technology, using a Modulated Lapped Transform (MLT). 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. A 14 kHz (32 ksps) extension, G.722.1/Annex C, was approved by ITU-T on May 14, 2005. Also known as the mono version of Siren 14, this extension is also available from Polycom as a royalty-free license.
The numbering of the wideband 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 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 as 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 wideband speech and delivers very low bitrates, is an ACELP
-based algorithm.
Audio codec
All codecs are devices or computer programs capable of coding or decoding a digital data stream or signal.The term audio codec has two meanings depending on the context:...
providing high quality, moderate bit rate
Bit rate
In telecommunications and computing, bit rate is the number of bits that are conveyed or processed per unit of time....
(24 and 32 kbit/s) wideband
Wideband Audio
Wideband audio is an audio technology used in telephony. It extends the frequency range of audio signals transmitted over telephone lines, resulting in higher quality speech. The range of the human voice extends from 80 Hz to 14 kHz but traditional, voiceband or narrowband telephone calls limit...
(50 Hz - 7 kHz audio bandwidth, 16 ksps (kilo-samples
Sampling rate
The sampling rate, sample rate, or sampling frequency defines the number of samples per unit of time taken from a continuous signal to make a discrete signal. For time-domain signals, the unit for sampling rate is hertz , sometimes noted as Sa/s...
per second) audio coding. It is a partial implementation of Siren
Siren Codec
Siren is a family of patented, transform-based, wideband audio codecs developed and licensed by PictureTel Corporation . There are three Siren codecs: Siren 7, Siren 14 and Siren 22....
7 codec (which offers bit rates 16, 24, 32 kbit/s) developed by PictureTel Corp. (now Polycom
Polycom
Polycom is a multinational corporation with approximately 3,200 employees worldwide and an annual revenue of approximately $1.2 billion in 2010. The company manufactures and sells telepresence and voice communications solutions.-Company History 1990:...
, Inc.). Its official name is Low-complexity coding at 24 and 32 kbit/s for hands-free operation in systems with low frame loss.
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
Monaural
Monaural or monophonic sound reproduction is single-channel. Typically there is only one microphone, one loudspeaker, or channels are fed from a common signal path...
version of Polycom
Polycom
Polycom is a multinational corporation with approximately 3,200 employees worldwide and an annual revenue of approximately $1.2 billion in 2010. The company manufactures and sells telepresence and voice communications solutions.-Company History 1990:...
's Siren 14 codec.
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 transform technology, using a Modulated Lapped Transform (MLT). 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. A 14 kHz (32 ksps) extension, G.722.1/Annex C, was approved by ITU-T on May 14, 2005. Also known as the mono version of Siren 14, this extension is also available from Polycom as a royalty-free license.
The numbering of the wideband 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 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 as 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 wideband speech and delivers very low bitrates, is an ACELP
ACELP
Algebraic code-excited linear prediction is a patented speech coding algorithm by VoiceAge Corporation in which a limited set of pulses is distributed as excitation to linear prediction filter....
-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.External links
- Official ITU-T G.722.1 standard - technical speciffication
- RFC 5577 - RTP Payload Format for ITU-T Recommendation G.722.1
- Polycom Siren/G 722.1 Page
- Polycom Siren14 G.722.1C Page