Audio decoder and decoding method

A non-transitory computer-readable medium storing instructions that, when executed by a device, cause the device to perform operations comprising:

• receiving, by a decoder, an input bitstream;
• dividing the input bitstream into a base signal bitstream and transformation parameter data;
• decoding, by a base signal decoder, the base signal bitstream to provide frequency-domain signals having a plurality of subbands;
• determining, in response to the transformation parameter data, a complex-valued convolution matrix, complex-valued, single-tap matrix coefficients, and real-valued matrix coefficients;
• applying, by a first matrix multiplication unit, the complex-valued convolution matrix to a first subband of the frequency-domain signals;
• applying, by a second matrix multiplication unit, the complex-valued, single-tap matrix coefficients to a second subband of the frequency-domain signals;
• applying, by a third matrix multiplication unit, the real-valued matrix coefficients to one or more remaining subbands of the frequency-domain signals;
• and
• converting, by a synthesis filterbank, output signals from the matrix multiplication units into a time-domain output.

A system comprising:

• a processor;
• and
• a non-transitory computer-readable medium storing instructions that, when executed by the processor, cause the processor to perform operations comprising:
• receiving, by a decoder, an input bitstream;
• dividing the input bitstream into a base signal bitstream and transformation parameter data;
• decoding, by a base signal decoder, the base signal bitstream to provide frequency-domain signals having a plurality of subbands;
• determining, in response to the transformation parameter data, a complex-valued convolution matrix, complex-valued, single-tap matrix coefficients, and real-valued matrix coefficients;
• applying, by a first matrix multiplication unit, the complex-valued convolution matrix to a first subband of the frequency-domain signals;
• applying, by a second matrix multiplication unit, the complex-valued, single-tap matrix coefficients to a second subband of the frequency-domain signals;
• applying, by a third matrix multiplication unit, the real-valued matrix coefficients to one or more remaining subbands of the frequency-domain signals;
• and converting, by a synthesis filterbank, output signals from the matrix multiplication units into a time-domain output.