| 摘要 |
Data compression apparatus in which input data is compressed according to a target output data quantity using a stage of data quantisation has one or more trial quantisers for selecting a degree of quantisation so that the target output data quantity is not exceeded; a data selector for selecting a subset of the current data to be quantised; a data store 700 for storing the subset of data; a backsearch quantiser 710 and dequantiser 720 for sequentially quantising and dequantising the subset of data at a plurality of degrees of quantisation including the degree of quantisation selected by the trial quantiser(s) and one or more harsher degrees of quantisation; a comparator 730 for comparing data quantised and dequantised by the backsearch quantiser with the stored subset of data, to detect errors introduced by the quantisation and dequantisation by the backsearch quantiser; and a quantisation selector for selecting a final degree of quantisation for use in compression of the current data, the final degree of quantisation being that degree detected by the comparator to introduce the fewest errors during quantisation and dequantisation of the subset of data by the backsearch quantiser. |
