Filling of non-coded sub-vectors in transform coded audio signals

摘要

A spectrum filler for filling non-coded residual sub-vectors of a transform coded audio signal includes a sub-vector compressor (42) configured to compress actually coded residual sub-vectors. A sub-vector rejecter (44) is configured to reject compressed residual sub-vectors that do not fulfill a predetermined sparseness criterion. A sub-vector collector (46) is configured to concatenate the remaining compressed residual sub-vectors to form a first virtual codebook (VC1). A coefficient combiner (48) is configured to combine pairs of coefficients of the first virtual codebook (VC1) to form a second virtual codebook (VC2). A sub-vector filler (50) is configured to fill non-coded residual sub-vectors below a predetermined frequency with coefficients from the first virtual codebook (VC1), and to fill non-coded residual sub-vectors above the predetermined frequency with coefficients from the second virtual codebook (VC2).

主权项

1. A method of filling residual sub-vectors that were not coded in a transform coded audio signal, which are referred to as non-coded residual sub-vectors, said method performed by a processing circuit configured as an audio decoder and comprising:
compressing the residual sub-vectors that were coded in the transform coded audio signal, which are referred to as coded residual sub-vectors, to obtain compressed residual sub-vectors; rejecting those compressed residual sub-vectors that do not fulfill a pre-determined sparseness criterion, to obtain remaining compressed residual sub-vectors; concatenating the remaining compressed residual sub-vectors to obtain coefficients comprising a first virtual codebook; combining pairs of the coefficients of the first virtual codebook to obtain coefficients comprising a second virtual codebook; filling the non-coded residual sub-vectors to obtain corresponding filled residual sub-vectors, based on using coefficients from the first virtual codebook to fill the non-coded residual sub-vectors that correspond to frequency bands below a predetermined frequency and, using coefficients from the second virtual codebook to fill the non-coded residual sub-vectors that correspond to frequency bands above the predetermined frequency; and forming an audio signal using the coded residual sub-vectors and the filled residual sub-vectors.