Data coding method and apparatus therefor

A data coding method wherein input data in prescribed data units is classified into a picture type whose data items are independently encoded and a picture type whose data items are encoded by being mutually related between each two thereof and the data items are encoded according to their respective picture type, whereby the thus-encoded data items are made up into a row of packs that is to be reproduced within a prescribed period of time and are stored into a unit, the data coding method comprising the steps of:

• determining an encoding rate;
• determining a fixed target amount of codes for each unit on the basis of the encoding rate;
• encoding the input data so that the coded data may be in conformity with the fixed target amount of codes for each unit;
• storing the encoded data temporarily;
• determining, on the basis of the encoding rate and the fixed target amount of codes, addresses of a reference unit for making a search and a prescribed number of units that are reproduced within at least N (N is a positive integer that is less than 16) frames before and after the reference unit;
• determining, on the basis of the temporarily stored and encoded data, an ending address at which there is ended at least data of the picture type having its data items independently encoded, of the data within the unit and an ending address of prescribed reference data that is uniquely discriminated from a foremost position of the unit;
• constructing as the unit the coded data that has been obtained by being encoded so that the coded data may be in conformity with the target amount of codes;
• and
• depicting at a foremost position of the unit the addresses of the unit and the ending address at which data of the picture type having its data items independently encoded is ended.

A data coding method wherein input data in units of prescribed data is encoded, comprising the steps of:

• determining an encoding rate;
• determining a target amount of codes in units of the prescribed data in correspondence with the encoding rate;
• determining transition in the amount of occupation of a virtual buffer that corresponds to a decoding buffer that is used when decoding is performed;
• encoding prescribed reference data of the input data so that the coded data may be in conformity with the target amount of codes that has been corrected according to a prescribed value into which the amount of occupation of the virtual buffer, prevailing at the point in time when encoding is performed, is made to converge;
• storing into within the unit the data that has been encoded as a row of packs that is to be reproduced within a prescribed period of time;
• determining, on the basis of the encoding rate, addresses of a reference unit for making a search and a prescribed number of units that are reproduced within at least N (N is a positive integer that is less than 16) frames before and after the reference unit and an ending address at which the prescribed reference data within the unit is ended;
• and
• depicting the address of the unit and the ending address at which the prescribed reference data within the unit is ended at a foremost position of the unit.