ITU-T is a standard for converting analog signals into digital signals in digital transmission systems. G.723, an ITU-T standard codec, uses ADPCM to compress and decompress speech on a 24 and 40 kbps channel. G.723 was introduced in 1988 and merged with G.721 to create G.726 in 1990.
FAQs About ITU-T Standard G.723
What is an ITU-T Standard?
An ITU-T standard is a protocol established by the International Telecommunications Union for digital transmission systems. Specifically, it is used for coding analogue signals into digital signals, with a focus on speech compression and decompression.
What is G.723?
G.723 is an ITU-T standard codec used for speech compression and decompression. It operates on a 24 and 40 kbps channel using the Adaptive Differential Pulse Code Modulation (ADPCM) standard for speech codecs. It was first introduced in 1988.
What is ADPCM?
ADPCM stands for Adaptive Differential Pulse Code Modulation. It is a form of speech coding that compresses analogue audio signals into digital ones by adapting to the input signal’s characteristics. It improves speech quality over low data rate channels while lowering the bits required to achieve acceptable quality.
Overview of G.723
G.723 is a subband codec that divides the audio signal into two different frequency bands for separate compression. The codec preserves speech quality at low bit rates by utilizing ADPCM. It has two modes: the 24 kbps mode (which uses two subbands) and the 40 kbps mode (which uses four subbands).
The codec also has a voice activity detection (VAD) function that determines if there is any speech activity in the signal. If it detects speech activity, the codec switches to the 40 kbps mode, which provides higher quality. In the absence of speech activity, it switches back to the 24 kbps mode to conserve bandwidth without significantly compromising speech quality.
G.723 was one of the first speech codecs to be used in VoIP systems, due to its low bit rate, VAD capabilities, and support for multiple channels. It has been widely adopted in various applications, including video conferencing, IP-based telephony networks, and Voice over Internet Protocol (VoIP).
In the long run
ITU-T standard G.723 is an essential codec for speech compression and decompression. It has played a crucial role in the advancement of digital transmission systems, enabling efficient speech communication over low data rate channels. With the introduction of newer, more advanced codecs, G.723 is being gradually phased out, but its legacy in the field of telecommunications remains significant.
