| 摘要 |
An encoder and a method therein for Pyramid Vector Quantizer, PVQ, shape search, the PVQ taking a target vector x as input and deriving a vector y by iteratively adding unit pulses in an inner dimension search loop. The method comprises, before entering a next inner dimension search loop for unit pulse addition, determining, based on the maximum pulse amplitude, maxamp y , of a current vector y, whether more than a current bit word length is needed to represent enloop y , in a lossless manner in the upcoming inner dimension loop. The variable enloop y is related to an accumulated energy of the vector y. The performing of this method enables the encoder to keep the complexity of the search at a reasonable level. For example, it enables the encoder to apply an increased precision loop only when it may be needed, by analyzing whether the "worst case scenario" in the upcoming inner loop would require an inner loop with a higher precision than the one currently used. |
