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What is the full form of ADPCM?

Full form of ADPCM: Here, we are going to learn what does ADPCM stands for? ADPCM – which is an abbreviation of "Adaptive Differential Pulse-Code Modulation" in Computer Acronyms/Abbreviations, etc.
Submitted by Anushree Goswami, on March 19, 2020

ADPCM: Adaptive Differential Pulse-Code Modulation

ADPCM is an abbreviation of "Adaptive differential pulse-code modulation".

It is an alternative modification of differential pulse-code modulation (DPCM) that varies the magnitude of the step of quantization, to enable additional diminution of the essential data bandwidth for a specified signal-to-noise ratio.

In general, the adaptation to signal data and information figures in ADPCM comprises basically of an adaptive scale parameter before quantizing the distinction in the DPCM encoder.

In 1973, ADPCM was built up and expanded for speech coding by P. Cummiskey, Nikil S. Jayant, and James L. Flanagan at Bell Labs.

In telephony

• In telephony, a standard audio signal for a single phone call is encoded as 8000 analog samples per second, of 8 bits each, providing a 64 kbit/s digital signal known as DS0.
• The default signal compression encoding on a DS0 is either μ-law (mu-law) PCM (North America and Japan) or A-law PCM (Europe and the majority of the rest of the world).
• These compressions are logarithmic compression systems where a 13 or 14 bit linear PCM sample number is mapped into an 8-bit value. This system is illustrated by international standard G.711. Where circuit expenditures are high and loss of voice quality is up to standard, it occasionally makes logic to compress the voice signal even more.
• An ADPCM algorithm is used to map a series of 8-bit μ-law (or a-law) PCM samples into a series of 4-bit ADPCM samples. In this manner, the capacity of the line is doubled. The technique is completely given in the G.726 standard.
• Many ADPCM systems of practices are used in voice over IP communications.
  At the beginning of the 1990s, ADPCM was also used by the Interactive Multimedia Association for the development of legacy audio codec known as ADPCM DVI, IMA ADPCM or DVI4.

Split Band ADPCM

• G.722 is an ITU-T standard wideband speech codec operating at 48, 56 and 64 kbit/s, based on subband coding with two channels and ADPCM coding of each.
• Before the digitization process, it holds the analog signal and classifies it in frequency bands with QMF filters (quadrature mirror filters) to obtain two subbands of the signal.
• When the ADPCM bitstream of each subband is achieved, the outcomes are multiplexed and the following step is storage or transmission of the data. The decoder has to carry out the reverse process, that is, demultiplex and decode each subband of the bitstream and recombine them.