Repetition reduced digital data record and playback system

Abstract

A record and playback system for reducing repetition redundancy is described in which during recording, a partially repetitive signal, such as a television signal, is converted into digital data words each representing the signal occurring during a particular TV line subinterval. A comparator unit receives the data words and compares each received word with a word from a recirculating storage that corresponds to the same line subinterval in its frame as that of the compared received data word. When the compared words differ by a predetermined value, the received word replaces the stored word in the storage and is also stored in a changed data memory as an updated data word along with address words. A recording control circuit intermittently causes the read out of data from the changed data memory for recording at selected positions of a data record. The storage includes alternately operating first and second recirculating storages which each store a set of data words equal in number to the number of data words of one-half a TV frame. Audio data words are stored for recording during vertical blanking intervals of the signal. On playback, a record pickup intermittently reads data words from the record to a record pickup memory whenever this memory is nearly empty. A composite signal generator reconstructs the recorded television signal from data words it receives from the display storage and display control.