# US 12,002,480 B2 · Audio decoder and decoding method

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- Number: US 12,002,480 B2
- Document ID: US12002480B2
- Status: Granted
- Kind: B2
- Application number: 18/351,769
- Filed: 2023-07-13
- Published: 2023-11-09
- Granted: 2024-06-04
- Earliest claimed: 2015-08-25
- Assignees: Dolby Laboratories Licensing Corporation; Dolby International AB
- Applicants: Dolby Laboratories Licensing Corporation; Dolby International AB
- Inventors: Dirk Jeroen Breebaart; David Matthew Cooper; Leif Jonas Samuelsson
- Web page: https://patentgrep.com/patent/US12002480B2

## CPC

- G10L 19/0212: {using orthogonal transformation}
- G10L 19/008: Multichannel audio signal coding or decoding using interchannel correlation to reduce redundancy, e.g. joint-stereo, intensity-coding or matrixing
- G10L 19/0204: {using subband decomposition}
- H04S 7/308: {Electronic adaptation dependent on speaker or headphone connection}
- H04R 2460/03: Aspects of the reduction of energy consumption in hearing devices
- H04S 2400/01: Multi-channel, i.e. more than two input channels, sound reproduction with two speakers wherein the multi-channel information is substantially preserved
- H04S 2420/01: Enhancing the perception of the sound image or of the spatial distribution using head related transfer functions [HRTF's] or equivalents thereof, e.g. interaural time difference [ITD] or interaural level difference [ILD]
- H04S 2420/03: Application of parametric coding in stereophonic audio systems
- H04S 2420/07: Synergistic effects of band splitting and sub-band processing
- G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
- H04S: STEREOPHONIC SYSTEMS
- H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K)

## Abstract

A method for representing a second presentation of audio channels or objects as a data stream, the method comprising the steps of: (a) providing a set of base signals, the base signals representing a first presentation of the audio channels or objects; (b) providing a set of transformation parameters, the transformation parameters intended to transform the first presentation into the second presentation; the transformation parameters further being specified for at least two frequency bands and including a set of multi-tap convolution matrix parameters for at least one of the frequency bands.

## Claims

### Claim 1

A method of decoding an encoded audio signal, 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.

### Claim 2

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.

### Claim 3

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.