Abstract:
The sampling frequency of a digital signal is converted from 96 kHz to 48 kHz for each frame by a down-sampling unit (13). The signal converted is compressed/encoded and output as a main code Im. A local signal corresponding to the main code Im is converted to a signal of sampling frequency of, for example, the original 96 kHz by an up-sampling unit (16) and an error signal between the this signal and an input digital signal is generated. Bits of a sample string of error signals are rearranged by rearrangement/encoding unit (18) and output as an error code Pe. At a decoding side, by using the main code Im and the error code Pe, it is possible to obtain a highly faithful reproduction signal or a reproduction signal based only on the main code Im.
Abstract:
From a sample SFC of a current frame, a sample string S similar to its head, sample string, and an end sample string is extracted, concatenated before and after the current frame as a substitute sample string AS, and subjected to filter processing or prediction encoding so as to obtain a processing result SOU of the current frame. In the case of the prediction encoding, auxiliary information indicating which part has been used is also output. This enables completion of processing within the current frame without significantly lowering continuity or efficiency, i.e., filter processing requiring processing over the preceding and the subsequent frame such as an interpolation filter, self feedback type prediction encoding, and decoding.
Abstract:
It is possible to increase the compression ratio of the encoding method using a dictionary such as LZ77, LZ78, LZW for sample strings of the audio signal and video signal. Each sample is aligned at the MSB side (73), divided from the MSB side into a character C1(i) for each character size (for example, 8-bit) N c . A dummy bit "0" is added to the divided portion not satisfying the N c to obtain one character as N c (74). Moreover, the least significant bit in each sample may be ignored. In each C1(i), each digit of the bits which can be ignored and the dummy bits is made "0" and a valid bit (digit) is made "1", thereby creating mask data M1(i) (75). By using the M1(i), C1(i) is compared to each character D(j) in the character string of the index j in the dictionary and check is made to determine whether the valid digit portion of C1(i) is matched. if matched, it is considered that C1(i) is matched with D(j).