G.729.1
Encyclopedia
G.729.1 is an 8-32 kbit/s embedded
speech and audio codec
providing bitstream
interoperability with G.729
, G.729 Annex A and G.729 Annex B. Its official name is G.729-based embedded variable bit rate
codec: An 8-32 kbit/s scalable wideband coder bitstream interoperable with G.729.
This codec has been designed to provide better quality and more flexibility than the existing ITU-T
G.729
speech coding standard.
G.729.1 is scalable in bit rate, acoustic
bandwidth and complexity.
In addition it offers various encoder and decoder modes, including the support of both 8 and 16 kHz
input/output sampling frequency, compatibility with G.729B, and reduced algorithmic
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 G.729
format.
The second layer (adds 4 kbit/s for a total of 12 kbit/s) is a narrowband
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 (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 technique referred to as Time-Domain Aliasing Cancellation (TDAC).
Embedded system
An embedded system is a computer system designed for specific control functions within a larger system. often with real-time computing constraints. It is embedded as part of a complete device often including hardware and mechanical parts. By contrast, a general-purpose computer, such as a personal...
speech and audio codec
Codec
A codec is a device or computer program capable of encoding or decoding a digital data stream or signal. The word codec is a portmanteau of "compressor-decompressor" or, more commonly, "coder-decoder"...
providing bitstream
Bitstream
A bitstream or bit stream is a time series of bits.A bytestream is a series of bytes, typically of 8 bits each, and can be regarded as a special case of a bitstream....
interoperability with G.729
G.729
G.729 is an audio data compression algorithm for voice that compresses digital voice in packets of 10 milliseconds duration. It is officially described as Coding of speech at 8 kbit/s using conjugate-structure algebraic code-excited linear prediction .Because of its low bandwidth requirements,...
, G.729 Annex A and G.729 Annex B. Its official name is G.729-based embedded variable bit rate
Bit rate
In telecommunications and computing, bit rate is the number of bits that are conveyed or processed per unit of time....
codec: An 8-32 kbit/s scalable wideband coder bitstream interoperable with G.729.
This codec has been designed to provide better quality and more flexibility than the existing ITU-T
ITU-T
The ITU Telecommunication Standardization Sector is one of the three sectors of the International Telecommunication Union ; it coordinates standards for telecommunications....
G.729
G.729
G.729 is an audio data compression algorithm for voice that compresses digital voice in packets of 10 milliseconds duration. It is officially described as Coding of speech at 8 kbit/s using conjugate-structure algebraic code-excited linear prediction .Because of its low bandwidth requirements,...
speech coding standard.
G.729.1 is scalable in bit rate, acoustic
Acoustic music
Acoustic music comprises music that solely or primarily uses instruments which produce sound through entirely acoustic means, as opposed to electric or electronic means...
bandwidth and complexity.
In addition it offers various encoder and decoder modes, including the support of both 8 and 16 kHz
Hertz
The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....
input/output sampling frequency, compatibility with G.729B, and reduced algorithmic
Algorithm
In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...
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 G.729
G.729
G.729 is an audio data compression algorithm for voice that compresses digital voice in packets of 10 milliseconds duration. It is officially described as Coding of speech at 8 kbit/s using conjugate-structure algebraic code-excited linear prediction .Because of its low bandwidth requirements,...
format.
The second layer (adds 4 kbit/s for a total of 12 kbit/s) is a narrowband
Narrowband
In radio, narrowband describes a channel in which the bandwidth of the message does not significantly exceed the channel's coherence bandwidth. It is a common misconception that narrowband refers to a channel which occupies only a "small" amount of space on the radio spectrum.The opposite of...
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 (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 technique referred to as Time-Domain Aliasing Cancellation (TDAC).
External links
- ITU-T Recommendation G.729.1 - technical specification
- Summary of G.729.1 (05/2006]
- RFC 4749 - RTP Payload Format for the G.729.1 Audio Codec
- RFC 5459 - G.729.1 RTP Payload Format Update: Discontinuous Transmission (DTX) Support