Patent ID: 7227898

Claim:
A digital signal conversion device comprising: decoding means for decoding a digital signal of a first format consisting of orthogonal transform coefficients of a predetermined unit; inverse quantization means for inversely quantizing the decoding digital signal; resolution conversion means for extracting a part of the orthogonal transform coefficients from adjacent blocks of orthogonal transform coefficient blocks of the predetermined unit of the inversely quantized digital signal, thus constituting partial blocks, converting the resolution; quantization means for quantizing the digital signal processed by resolution conversion; and coding means for coding the quantized digital signal, thus generating a digital signal of a second format; wherein said partial block connection step multiplies a first matrix, a second matrix and a third matrix, so as to form said new block, said first matrix being an 8×8 matrix, said second matrix being two 4×4 matrices and said third matrix being a 1×8 matrix; wherein said digital signal conversion occurs in a frequency domain in one of either two modes, a static mode or a dynamic mode; wherein in said static mode an 8×8 Discrete Cosine Transform (DCT) is carried out on 8×8 pixels from one of the respective blocks of the digital signal, the one block having one DC component and 63 AC components; and wherein in said dynamic mode an 8×8 block is divided into a 4×8 block of a first field and a 4×8 block of a second field, and a 4×8 DCT is carried out on 4×8 pixels from one of the respective blocks of the digital signal, the one block having one DC component and 31 AC components.