| 摘要 |
A differential pulse code modulation apparatus comprises an error signal generator for receiving an input video signal comprising successive words representing video samples, and being operative to produce therefrom an error signal of which successive words each represent a difference between a word of the input signal and a predicted value therefor, a compander for compressing and expanding the error signal to produce a received video signal, an adder for adding successive words of the received video signal to successive words of a predicted value signal representing the predicted values to produce a received error signal, and a predictor responsive to the received error signal to produce the predicted value signal, the transfer function of the compander having been established in dependence on the minimum numbers of quantizing levels required to quantize a picture element of a video signal without the quantization levels being visually apparent for each of a range of input frequencies of the video signal. |
