A modified adaptive delta modulator for video data compression

The results of a study in data compression of adaptive delta modulated (ADM) video signals are presented. The Song mode ADM is first investigated and shown not to produce enough redundancy to warrant entropy encoding. A modified adaptive delta modulator algorithm is presented that produces sufficient redundancy to yield a 40 to 50% data compression by using a simple 4-bit block code. Other techniques such as field interpolation and direct substitution are shown to further increase the possible data compression without noticeable degradation in the two input images used in this investigation. A frame freeze unit is presented that can be used in conjunction with the modified modulator to capture a frame a video for transmission over a computer network. The effects of channel error in the transmission of packet video over a computer network are considered. A leaky integrator is used to reduce the effects of channel errors in the data bits. It is shown that the effects of channel errors on the block code header bits can be reduced by field interpolation those packet that can be determined to contain error on header bits.