DPCM video signal compression and transmission system and method

Claim 1

A method of differential pulse code modulation compression of a video signal, comprising the steps of: selecting quantization levels and ranges for a predetermined range of video signals and selecting reconstructed signal levels for each quantization range; calculating, for each possible combination of each possible value of an incoming video signal in the predetermined range and a feedback signal comprising all possible values in the video signal range, a compressed video difference output signal according to the preselected quantization characteristic and a reconstructed video signal value corresponding to that video difference signal according to the preselected reconstructed signal levels; storing the calculated input, output and reconstructed signals in the form of look-up tables in an encoder PROM, the tables simulating an encoder quantization function and an encoder reconstructor function, the PROM having a quantizer function input, a feedback input, a quantizer function output, and a reconstructor function output; connecting the quantizer function input to a source of digital video signals; connecting the reconstructor function output to the feedback input via a latch for producing one pixel delay in the signal; controlling the PROM reconstructor function to form, for each incoming pair of video and feedback signals, the corresponding reconstructed video feedback signal and a quantizer function compressed video difference output signal, and to provide the reconstructed video signal at the reconstructor function output and the compressed video difference output signal at the quantizer function output; and connecting the compressed video difference output signal to a video transmitter.

Claim 2

A method of differential pulse code modulation compression of a video signal, comprising the steps of: selecting quantization levels and ranges for a predetermined range of video signals and selecting reconstructed signal levels for each quantization range; calculating, for each possible combination of each possible value of an incoming video signal in the predetermined range and a feedback signal comprising all possible values in the video signal range, a compressed video difference output signal according to the preselected quantization characteristic and a reconstructed video signal value corresponding to that video difference signal according to the preselected reconstructed signal levels; storing the calculated input, output and reconstructed signals in the form of look-up tables in an encoder PROM, the tables simulating an encoder quantization function and an encoder reconstructor function, the PROM having a quantizer function input, a feedback input, a quantizer function output, and a reconstructor function output; connecting the quantizer function input to a source of digital video signals; connecting the reconstructor function output to the feedback input via a latch for producing one pixel delay in the signal; controlling the PROM reconstructor function to form, for each incoming pair of video and feedback signals, the corresponding reconstructed video feedback signal and a quantizer function compressed video difference output signal, and to provide the reconstructed video signal at the reconstructor function output and the compressed video difference output signal at the quantizer function output; and connecting the compressed video difference output signal to a video transmitter.

Claim 5

A system for transmitting compressed, DPCM encoded video signals, comprising: a single PROM connected to a source of digital video signals in a predetermined input signal range, the PROM being preprogrammed with tables comprising all possible combinations of reconstructed video signals and output compressed video signals for each possible combination of values of an input video signal and a feedback signal in the predetermined range, the tables of values being calculated from preselected quantization levels and ranges, the PROM having a video signal quantizer function input, a feedback signal input, a compressed video signal output, and a reconstructor function output and being programmed to look up the corresponding compressed video signal and reconstructed signal for each pair of input signals and to provide these signals at its respective outputs; and a latch connected between the reconstructor function output and feedback signal input of the PROM, and clock means for controlling the latch to produce a one pixel delay in the feedback signal.

Claim 6

A system for transmitting compressed, DPCM encoded video signals, comprising: a single PROM connected to a source of digital video signals in a predetermined input signal range, the PROM being preprogrammed with tables comprising all possible combinations of reconstructed video signals and output compressed video signals for each possible combination of values of an input video signal and a feedback signal in the predetermined range, the tables of values being calculated from preselected quantization levels and ranges, the PROM having a video signal quantizer function input, a feedback signal input, a compressed video signal output, and a reconstructor function output and being programmed to look up the corresponding compressed video signal and reconstructed signal for each pair of input signals and to provide these signals at its respective outputs; and a latch connected between the reconstructor function output and feedback signal input of the PROM, and clock means for controlling the latch to produce a one pixel delay in the feedback signal.