G.729.1 is an 8-32 kbit/s embedded speech and audio

codec A codec is a device or computer program that encodes or decodes a data stream or signal. ''Codec'' is a portmanteau of coder/decoder. In electronic communications, an endec is a device that acts as both an encoder and a decoder on a signal or da ...

providing

bitstream A bitstream (or bit stream), also known as binary sequence, is a sequence of bits. A bytestream is a sequence of bytes. Typically, each byte is an 8-bit quantity, and so the term octet stream is sometimes used interchangeably. An octet may ...

interoperability with

G.729 G.729 is a royalty-free narrow-band vocoder-based audio data compression algorithm using a frame length of 10 milliseconds. It is officially described as ''Coding of speech at 8 kbit/s using code-excited linear prediction'' speech coding (CS-ACEL ...

, G.729 Annex A and G.729 Annex B. Its official name is ''G.729-based embedded variable

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 w ...

codec: An 8-32 kbit/s scalable wideband coder bitstream interoperable with G.729''. It was introduced in 2006. This codec has been designed to provide better quality and more flexibility than the existing

ITU-T The ITU Telecommunication Standardization Sector (ITU-T) is one of the three sectors (divisions or units) of the International Telecommunication Union (ITU). It is responsible for coordinating standards for telecommunications and Information Commu ...

speech coding standard. G.729.1 is scalable in bit rate, acoustic

bandwidth Bandwidth commonly refers to: * Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range * Bandwidth (computing), the rate of data transfer, bit rate or thr ...

and complexity. In addition it offers various encoder and decoder modes, including the support of both 8 and 16

kHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that on ...

input/output sampling frequency, compatibility with G.729B, and reduced

algorithm In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific Computational problem, problems or to perform a computation. Algorithms are used as specificat ...

ic delay. The bitstream of G.729.1 is structured into 12 hierarchical layers. The first layer (or core layer) at 8 kbit/s follows the

format. The second layer (adds 4 kbit/s for a total of 12 kbit/s) is a

narrowband Narrowband signals are signals that occupy a narrow range of frequencies or that have a small fractional bandwidth. In the audio spectrum, narrowband sounds are sounds that occupy a narrow range of frequencies. In telephony, narrowband is usua ...

enhancement layer. The third layer (2 kbit/s for a total of 14 kbit/s) is a bandwidth extension layer. Further layers (in 2 kbit/s steps) are wideband enhancement layers. The G.729.1 output bandwidth is 50–4000 Hz at 8 and 12 kbit/s, and 50–7000 Hz from 14 to 32 kbit/s. G.729.1 is also known as G.729 Annex J and G.729EV where EV stands for Embedded Variable (bit rate). The G.729.1 algorithm is based on a three-stage coding structure: embedded

code-excited linear prediction Code-excited linear prediction (CELP) is a linear predictive speech coding algorithm originally proposed by Manfred R. Schroeder and Bishnu S. Atal in 1985. At the time, it provided significantly better quality than existing low bit-rate algori ...

(CELP) coding of the lower band (50–4000 Hz), parametric coding of the higher band (4000–7000 Hz) by Time-Domain Bandwidth Extension (TDBWE), and enhancement of the full band (50–7000 Hz) by a predictive

transform coding Transform coding is a type of data compression for "natural" data like audio signals or photographic images. The transformation is typically lossless (perfectly reversible) on its own but is used to enable better (more targeted) quantization, whi ...

technique referred to as

time-domain aliasing cancellation 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 su ...

(TDAC) or

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 transform, lapped: it is designed to be performed on consecutive blocks of a larger ...

(MDCT) coding. As of January 1, 2017, the patent terms of most licensed

patents A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an enabling disclosure of the invention."A p ...

under the G.729 Consortium have expired, the remaining unexpired patents are usable on a

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 ...

basis.

References

External links

ITU-T Recommendation G.729.1
- technical specification

* - RTP Payload Format for the G.729.1 Audio Codec * - G.729.1 RTP Payload Format Update: Discontinuous Transmission (DTX) Support {{Compression formats Audio codecs Speech codecs ITU-T recommendations ITU-T G Series Recommendations

See also

References

External links