The authors report the results of an investigation into the single transcoding performance effects of synchronous code correction (SCC) on the draft American National Standard embedded ADPCM (adaptive differential pul...
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The authors report the results of an investigation into the single transcoding performance effects of synchronous code correction (SCC) on the draft American National Standard embedded ADPCM (adaptive differential pulse code modulation) algorithm (***). It is established through analysis and simulations that the inclusion of the SCC property in *** will guarantee no loss in PCM-to-PCM signal-to-noise ratio (SNR) measurements and for many input signals will improve the PCM-to-PCM SNR. The SNR improvements are shown to be modest, which leaves as an open issue the question of whether the SCC complexity is justified.
A picture-coding method called mesh differential pulse-codemodulation (MDPCM) is described. The difference between the MDPCM and DPCM lies mainly in the point that the DPCM is causal while the MDPCM is not. Computer ...
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A picture-coding method called mesh differential pulse-codemodulation (MDPCM) is described. The difference between the MDPCM and DPCM lies mainly in the point that the DPCM is causal while the MDPCM is not. Computer simulations for MDPCM are given, and it is shown that the MDPCM is more effective than the DPCM. The MDPCM can offer a reasonable tradeoff between the compression rate and distortion. Operations of this algorithm are quite simple. A design for a real-time parallel system using chips of TMS320 family as processors of processing elements is given.< >
Quantization errors of a sigma-differential pulse code modulation (SDPCM), a multibit version of sigma-delta modulation, are analyzed in the time domain. It is shown that a certain type of sampling rate reduction alwa...
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ISBN:
(纸本)9517212402
Quantization errors of a sigma-differential pulse code modulation (SDPCM), a multibit version of sigma-delta modulation, are analyzed in the time domain. It is shown that a certain type of sampling rate reduction always reduces the worst-case quantization error rN times where r is a factor of rate reduction and N is the order of the SDPCM.
The latest generation of DSPs has enabled a new range of algorithms to be implemented in real-time. An inevitable side-product of this is that algorithms developed for much slower processors will now run many times fa...
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The latest generation of DSPs has enabled a new range of algorithms to be implemented in real-time. An inevitable side-product of this is that algorithms developed for much slower processors will now run many times faster than real-time. This, along with a suitable on-chip serial interface, enables a single DSP to process several channels on a PCM stream in real-time. The principle behind DSP multi-tasking is that every task should process a frame of data, after which it releases control of the processor at least until its next frame is ready. The neatest and most flexible way of achieving this is with a nonpreemptive scheduling mechanism, with a device driver to handle the input and output of sampled data. This paper briefly describes the multi-tasking operating system, the approach taken to software development on the DSP32C, and some applications.< >
A voice coder subsystem using the TMS320C10 DSP and a codec with an interfacing ASIC has been shown to be a practical realisation for CT2 (the second generation cordless telephone). The reduced G.721 ADPCM algorithm d...
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A voice coder subsystem using the TMS320C10 DSP and a codec with an interfacing ASIC has been shown to be a practical realisation for CT2 (the second generation cordless telephone). The reduced G.721 ADPCM algorithm discussed is currently available as a standard ready-masked DSP device. Speech quality and signal to noise has been compared with that of a G.721 voice coder using typical speech signals. The results indicate a slight improvement of both parameters. Formal approval of the device for use in CT2 has been obtained. The design has met the requirements of this application. An upgraded version of the design, based on a custom-designed DSP, has been introduced recently for the new CAI standard. Whilst the latter version offers better power consumption and a higher degree of integration, the original DSP design was the first such speech coder system to have been designed and remains a practical and competitive design solution.< >
Methods for the design of cost-effective one-stage PCM switching networks composed of digital switching matrices are proposed. These one-stage networks have, in many cases, a more regular structure and contain fewer e...
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Methods for the design of cost-effective one-stage PCM switching networks composed of digital switching matrices are proposed. These one-stage networks have, in many cases, a more regular structure and contain fewer elements than networks currently known. The proposed one-stage networks can also be used as submodules for multistage networks.
Minimum mean squared error (MMSE) fixed-lag smoothing is used in conjunction with DPCM (differential pulse code modulation) to develop a code generator employing delayed decoding. This smoothed DPCM (SDPCM) code gener...
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Minimum mean squared error (MMSE) fixed-lag smoothing is used in conjunction with DPCM (differential pulse code modulation) to develop a code generator employing delayed decoding. This smoothed DPCM (SDPCM) code generator is compared to DPCM and interpolative DPCM (IDPCM) code generators at rates 1 and 2 for tree coding several synthetic sources, as well as to a DPCM code/generator at rate 2 for speech sources. The (M, L) algorithm is used for tree searching, and SDPCM outperforms IDCPM and DPCM at rate 2 for synthetic sources with M = 1, 4, 8, and 12, and at rate 1 with M ≥ 4. For speech, SDPCM provides a slight improvement in MSE (mean squared error) over DPCM codes, which is also evident in sound spectrograms and listening tests.
The technique of pulse-Position-modulation offers greater receiver sensitivity than PCM, and is ideally suited to optical sources. A broad analysis shows that more taps could be made available on an existing multi-poi...
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A differential pulse code modulation (DPCM) system provides a fast and inexpensive data compression technique for analog signals. Two methods of improving the performance of DPCM systems are studied: the introduction ...
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A differential pulse code modulation (DPCM) system provides a fast and inexpensive data compression technique for analog signals. Two methods of improving the performance of DPCM systems are studied: the introduction of delays using incremental tree coding techniques and the design of nonuniform quantizers based upon optimization theory. The performance of matched integrator, perfect integrator, and optimization-based DPCM systems are compared for first-order Gauss-Markov sources and mean square error using simulation techniques. Both methods improve system performance. The optimization-based DPCM system provides substantial improvement for high bit rates.
In DPCM (differential pulse code modulation) or HDPCM (hybrid DPCM) of coloured pictures consisting of three components, every component can be coded with three separate coders, each containing a scalar quantizer. How...
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In DPCM (differential pulse code modulation) or HDPCM (hybrid DPCM) of coloured pictures consisting of three components, every component can be coded with three separate coders, each containing a scalar quantizer. However, more compression can be obtained with one vector quantizer instead of three scalar quantizers. In the article, the attention is focused on the placement of the output vectors in the two-dimensional prediction error plane using visual masking functions.< >
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