Proceedings ArticleDOI
An implementation of a variable rate codec based on ADPCM with multi-quantizer (ADPCM-MQ)
Tomita Yoshihiro,Kohei Iseda,Tomohiko Taniguchi,Shigeyuki Unagami +3 more
- pp 1080-1084
TLDR
The authors propose a method for the combined use of constant SNR (signal/noise ratio) and constant noise to determine optimum bit/rate control of the VRC.Abstract:
Discusses an implementation of an experimental variable bit rate codec (VRC) based on adaptive differential pulse code modulation with a multiquantizer (ADPCM-MQ) that processes speech signals at 16 kb/s to 48 kb/s The authors propose a method for the combined use of constant SNR (signal/noise ratio) and constant noise to determine optimum bit/rate control of the VRC This algorithm was implemented using six digital signal processor chips The average bit rate of the prototype codec for the telephone voice channel was about 23 kb/s, including supplementary information, and a quality better than that specified in G721 (32 kb/s ADPCM) was observed >read more
Citations
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Patent
Variable rate coder
TL;DR: In this paper, a variable rate coder for transforming an input signal into a low bit rate digital signal, comprising of a plurality of coding units each comprising an output quantizer having a different number of output bits, is provided.
Patent
Method and apparatus for selecting an encoding rate in a variable rate vocoder
TL;DR: In this paper, an apparatus for selecting an encoding rate for an input signal (S(n) consisting of an audio signal detection device for determining whether audio signal is present in each frequency subband of the input signal, and an encoder-decoder system for selecting the encoding rate in accordance with the determination as to whether audio signals are present in the subband.
References
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Journal ArticleDOI
Digital coding of speech waveforms: PCM, DPCM, and DM quantizers
TL;DR: It is pointed out that error waveforms in speech quantization cannot be regarded as additive white noise, in general, and that for finer assessments of speech coders, either relative or absolute, one needs to supplement SNR-based observations with corrections for subjective and perceptual factors.
Journal ArticleDOI
Embedded DPCM for Variable Bit Rate Transmission
TL;DR: In this paper, an adaptive DPCM (ADPCM) encoder and decoder is proposed for variable rate transmission with variable bit rates up to any desired maximum. But the decoded analog signal is substantially noisier than the output of an ADPCM encoder with D = E - C bits/sample.
Proceedings Article
Embedded DPCM for variable bit rate transmission
TL;DR: Within the bit stream of an embedded digital code is a stream that can be decoded to produce a reasonable replica of the analog source signal, and with minor modifications to the encoder and decoder, DPCM becomes an embedded code.
Journal ArticleDOI
Variable rate coding of speech
J. J. Dubnowski,R. Crochiere +1 more
TL;DR: It is shown that by careful design the algorithm can be made to be as robust to channel errors as that of a fixed rate adpcm coder.
Journal ArticleDOI
A High Performance LSI Digital Signal Processor for Communication
TL;DR: A newly developed CMOS LSI DSP (FDSP3) is described, which has a powerful multiplier, which operates at a rate of 10 M-operations/s, almost twice as fast as the fastest existing L SI DSP's.