Abstract: A decoding apparatus and a decoding method are capable of minimizing degradation of the quality of images and sounds when a synchronous signal error occurs. The decoding apparatus includes a frame counter for receiving a bit stream, a synchronous pattern detector, a data error check unit, a synchronous detector, and a frame error determination unit. A synchronous detection error occurrence signal produced by the synchronous detector is not output to an external error processing circuit but is directly transmitted to the frame error determination unit. Even when the timing of an output synchronous pattern detection signal from the synchronous pattern detector and the timing of an output frame position signal from the frame counter do not match each other and a frame synchronous abnormality occurs, if the data itself is normal then decoding processing is executed without performing any error correction processing.

Abstract: A decoding apparatus includes a quantized bit count storage, a sound-image data decomposer, a unit frame length calculator, a quantized bit count adder, a quantized bit total value storage, a comparator, and a decoding processor. The comparator compares the value of the unit frame length of an input compressed bit stream with the quantized bit total value of the compressed bit stream, and outputs an error occurrence signal if the quantized bit total value exceeds the value of the unit frame length. If the comparator outputs the error occurrence signal to the decoding processor, the decoding processor performs interpolation processing for a sound-image signal and thereby prevents production of noise which is produced when the quantized bit total value exceeds the value of the unit frame length.

Abstract: An audio coding device which includes an analyzing unit for conducting frequency analyses of an input audio signal, a bit weighting unit for generating a weight signal based on an analysis signal, and a filter for converting an input audio signal into a plurality of frequency band signals. The audio coding device also has a bit allocating unit for generating quantization data from a frequency band signal based on a value of a weight signal, and a frame packing unit for generating compression data from quantization data and outputting the compression data. A frame completion determining unit determines whether weight allocation processing is normally completed or not, and a storage unit stores the last weight signal recognized as having weight allocation processing normally completed.

Abstract: As a selected subband signal, selected is one of frequency band signals of an input signal that has a maximal signal to mask ratio. The selected subband signal is assigned, as a primary provisional bit number, with a maximal quantization bit number allocatable thereto. A primary mask to noise ratio of the selected subband signal is calculated. Other subband signals are assigned with temporary bit numbers incremented one by one from zero with secondary mask to noise ratios of the other subband signal meanwhile calculated each time when the temporary bit numbers are incremented by one. The temporary bit numbers are allocated to the other subband signals as secondary provisional bit numbers when the secondary mask to noise ratios individually exceed the primary mask to noise ratio. Some of the secondary provisional bit numbers may be equal to zero. A sum of the primary and the secondary provisional bit numbers is compared with a total of quantization bit numbers allocatable to the frequency band signals.