Transform coding apparatus with evaluation of quantization under inverse transformation

摘要

In an apparatus for recording and transmitting audio and/or video data, a high efficiency coding apparatus digitalizes input signals on the basis of a lesser amount of data by use of transform coding. In the transform coding of audio and/or video signals, a plurality of quantizers slightly different from each other for transform coefficients are provided. The quantized results are inversely transformed by IDCTs to obtain respective reproduced signals. The obtained reproduced signals are compared with input signals by subtracters for error evaluation. The optimum quantization results are selected by a code selector. It is thus possible to execute accurate quantization.