LOW-DELAY AUDIO SIGNAL CODER UTILIZING ANALYSIS TECHNOLOGY BY SYNTHESIS

摘要

PURPOSE: To provide a low-delay coder utilizing an analysis technique by synthesis by executing the adaptation of the prediction order of a synthesis filter on both sides of coding and decoding. CONSTITUTION: A filter adaptive device AFC is composed of serial two devices, a first ACC adapts a filter coefficient and a second APC adapts a prediction order. Filters FP, SP1-SP3 and SYC are grid type filters for directly utilizing the reflection coefficient of an acoustic tube and the device ACC leads out the coefficients from signals present in the output 21 of the filter SYC. The coefficients are supplied to the various filters by connection 24, and in the case of dynamic bit allocation, the coefficients are also supplied to the device UAD by the branching of the connection 24 and a function Wi utilized in the allocation is updated. Then, the device APC decides the value (p) of the prediction order to be utilized for a coding vector within an interval determined by a minimum prediction order and a maximum prediction order.