An audio signal recording and reproducing apparatus comprising:
- an analog to digital converter which digitizes sound into a digitized signal;
- an input data difference operator connected to receive the digitized signal and to output difference data representing changes in the digitized signal;
- means for data compressing the difference data into conversion values to reduce information quantity and for extending the conversion values into reproduced difference data;
- a semiconductor memory connected to receive and store the conversion values from the means for compressing and to supply the conversion values to the means for extending;
- an output data difference operator connected to receive the reproduced difference data and to output a reproduced digitized signal;
- and
- a digital to analog converter connected to receive the reproduced digitized signal and to output a reproduced output analog signal;
- the means for compressing and extending including a plurality of input compression and output extension conversion tables which are used for compression conversion of the difference data into the conversion values and for extension conversion of the conversion values into the reproduced difference data, respectively, each input compression conversion table containing conversion values corresponding to a range of values of difference data, the input compression conversion tables being arranged in succession, the conversion values of each successive input compression conversion table corresponding to a successively larger range of difference data values, the output extension conversion tables being arranged in succession, each successive output extension conversion table containing a successively larger range of values of reproduced difference data corresponding to the conversion values, wherein compression conversion of the difference data into conversion signals includes reading conversion signals out of a selected one of the input compression conversion tables, and wherein extension conversion of the conversion values into reproduced difference data includes reading the reproduced difference data out of a selected one of the output extension conversion tables;
- and
- input compression and output extension conversion table selection counters which contain one of a plurality of count values, each of the plurality of count values corresponding to one of the input compression and output extension conversion tables, respectively, the input compression and output extension selection counters being count-controlled by the difference data and conversion values, respectively, to select the selected one among the plurality of input compression and output extension conversion tables, respectively, which corresponds with the count value contained by the counters.