| 摘要 |
An adaptive quantizing device for use in a differential encoder which makes use of a device input signal variable in a predetermined dynamic range, a local decoded signal, and a local input signal from a prediction signal. The quantizing arrangement (12, 13) is provided for adaptively quantizing a difference between the device and the local input signals into a quantization output signal in accordance with a predetermined quantization characteristic so that the local decoded signal never exceeds the dynamic range even if the quantization output signal is accompanied by a quantization error of a maximum value. Preferably, the quantizing arrangement comprises a converting circuit (16) for quantizing the device input signal into a converted signal in accordance with a preselected quantization characteristic for use in making a single quantizer (13) adaptively quantize the difference into the quantization output signal. Alternatively, the quantizing arrangement may comprise three quantizers and a selecting arrangement for adaptively selecting one of outputs of the three quantizers. A read-only memory is preferred in implementing each of the single quantizer, the converting circuit, the three quantizers, and a combination of the three quantizers and the selecting arrangement.
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