Facsimile and static presentation processing – Facsimile – Auxiliary signal
Patent
1993-07-22
1995-05-02
Rogers, Scott A.
Facsimile and static presentation processing
Facsimile
Auxiliary signal
358426, 358430, 3582612, 348405, 348419, H04N 1415
Patent
active
054124840
ABSTRACT:
A variable rate coder/decoder system in which a quantizer, under control of a quantization controller, quantizes a signal obtained by subjecting discrete cosine transformation of a difference signal between an input signal and a signal from a frame memory storing therein a previous frame with a first quantization step width calculated based on a power value of the input signal calculated by a power calculator and a predetermined first signal-to-quantization noise ratio. In the system, further, a re-quantizer quantizes a difference signal between a signal being not quantized by the quantizer and a signal after the inverse quantization of an inverse quantizer with a second quantization step width calculated based on the power value controlled by a re-quantization controller and a predetermined second signal-to-quantization noise ratio. Variable length encoders subject the quantization output signals of the quantizer and re-quantizer to variable length encoding, decrease discard priority for the quantization output signal of the quantizer, increase discard priority for the quantization output signal of the re-quantizer, and then transmit them in the form of fixed-length cells or variable-length packets whereby, even when the amount of input data varies, its quality can be maintained constant and encoding and decoding can be realized with a high efficiency.
REFERENCES:
patent: 4984076 (1991-01-01), Watanabe et al.
patent: 5117234 (1992-05-01), Shizawa
Kabushiki Kaisha Toshiba
Rogers Scott A.
Stoll Thomas L.
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