Abstract: A signal recording method for recording a signal having improved sound quality while maintaining interchangeability with the pre-existing format for a digital audio disc or the like. An input signal to a signal recording device is a signal obtained on sampling with the sampling frequency exceeding 4.1 kHz and/or a signal having the number of quantization bits exceeding 16. The input signal is split by a band-splitting filter 3 into a main signal which is a 16-bit signal and a plurality of sub-signals of the frequency range other than the above frequency. Each sub-signal has its priority set by a priority calculating unit 5. The sub-signals are synthesized in the order of the decreasing priority to an inaudible area of the main signal as found by a required bit number calculating unit 4.

Abstract: A digital signal processing method and apparatus processes a signal obtained on splitting the entire frequency band of an input digital signal into a plurality of sub-bands. The entire frequency band of the input digital signal is split into a plurality of sub-bands, and signals of each sub-band are allocated to a plurality of sub-words divided from a word of the input digital signal. In allocating the signals, the information for reducing the noise in at least one of the sub-bands is allocated to the sub-word different from the sub-word to which is allocated the signal of the sub-band whose noise is to be reduced.

Abstract: An audio signal recording and reproduction apparatus enabling a low frequency band signal component to be reproduced by existing reproduction apparatuses and a high frequency band component to be processed as well. A digital audio signal is divided into a low frequency band signal component and high frequency band signal component by a frequency band division filter. The low band signal component is subjected to straight PCM processing to maintain compatibility with existing reproduction methods. The high frequency band signal component is subjected to high frequency coding through a requantization circuit and entropy coding circuit. A comparison circuit compares the straight PCM signals and the high efficiency coded signals to determine if they will fit into a predetermined bit length and, when not fitting, causes the requantization circuit to perform requantization to shorten the bit length.