# US 2021/0343301 A1 · High resolution audio coding > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0343301 A1 - Document ID: US20210343301A1 - Status: Published application - Kind: A1 - Application number: 17/372,951 - Filed: 2021-07-12 - Published: 2021-11-04 - Earliest claimed: 2019-01-13 - Assignees: Huawei Technologies Co., Ltd. - Applicants: Huawei Technologies Co., Ltd. - Inventors: Yang GAO - Web page: https://patentgrep.com/patent/US20210343301A1 ## CPC - G10L 19/06: Determination or coding of the spectral characteristics, e.g. of the short-term prediction coefficients - G10L 19/032: Quantisation or dequantisation of spectral components - G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING ## Abstract Methods, systems, apparatuses, and computer programs encoded on computer storage media for performing linear predictive coding (LPC) are described. At least one of a differential spectrum tilt and an energy difference between a current frame and a previous frame of the audio signal is determined. A spectral stability of the audio signal is detected based on at least one of the differential spectrum tilt and an energy difference between the current frame and the previous frame of the audio signal. In response to detecting the spectral stability of the audio signal, quantized LPC parameters for the previous frame are copied into the current frame of the audio signal. ## Claims ### Claim 1 A computer-implemented method for performing linear predictive coding (LPC) of an audio signal, comprising: determining at least one of a differential spectrum tilt and an energy difference between a current frame and a previous frame of the audio signal; detecting a spectral stability of the audio signal based on at least one of the differential spectrum tilt and the energy difference between the current frame and the previous frame of the audio signal; and in response to detecting the spectral stability of the audio signal, copying quantized LPC parameters for the previous frame into the current frame of the audio signal. ### Claim 2 (depends on 1) The computer-implemented method of claim 1, wherein detecting the spectral stability of the audio signal based on at least one of the differential spectrum tilt and the energy difference between the current frame and the previous frame of the audio signal comprises: determining an absolute value of the differential spectrum tilt between the current frame and the previous frame for the audio signal; determining an absolute value of the energy difference between the current frame and the previous frame of the audio signal; and in response to determining that at least one of a change of the absolute value of the differential spectrum tilt and a change of the absolute value of the energy difference has been within a predetermined range for at least a predetermined number of frames, determining that the spectral stability of the audio signal is detected. ### Claim 3 (depends on 1) The computer-implemented method of claim 1, further comprising: determining that the spectral stability of the audio signal is not detected based on at least one of the differential spectrum tilt and the energy difference between the current frame and the previous frame of the audio signal; and in response to determining that the spectral stability of the audio signal is not detected, performing a quantization on LPC parameters for the current frame to generate quantized LPC parameters for the current frame. ### Claim 4 (depends on 3) The computer-implemented method of claim 3, wherein determining that the spectral stability of the audio signal is not detected based on at least one of the differential spectrum tilt and the energy difference between the current frame and the previous frame of the audio signal comprises at least one of the following: determining an absolute value of the differential spectrum tilt between the current frame and the previous frame for the audio signal; and determining that a change of the absolute value of the differential spectrum tilt has not been within a predetermined range for at least a predetermined number of frames; or determining an absolute value of the energy difference between the current frame and the previous frame of the audio signal; and determining that a change of the absolute value of the energy difference has not been within a predetermined range for at least a predetermined number of frames. ### Claim 5 (depends on 1) The computer-implemented method of claim 1, further comprising: determining that the quantized LPC parameters has been copied for at least a predetermined number of frames prior to the current frame; and in response to determining that the quantized LPC parameters has been copied for at least the predetermined number of frames prior to the current frame, performing a quantization on LPC parameters for the current frame to generate quantized LPC parameters for the current frame. ### Claim 6 (depends on 1) The computer-implemented method of claim 1, further comprising: sending a bit to a decoder indicating that the quantized LPC parameters are copied from the previous frame. ### Claim 7 (depends on 1) The computer-implemented method of claim 1, further comprising: in response to detecting the spectral stability of the audio signal, performing a quantization on a differential energy level between the current frame and the previous frame to generate a quantized differential energy level; and in response to determining that the spectral stability is not detected, performing a quantization on an energy level of the current frame to generate a quantized energy level of the current frame. ### Claim 8 An electronic device, comprising: a memory; and one or more processors in communication with the memory, wherein the one or more processors are configured to: determine at least one of a differential spectrum tilt and an energy difference between a current frame and a previous frame of an audio signal; detect a spectral stability of the audio signal based on at least one of the differential spectrum tilt and the energy difference between the current frame and the previous frame of the audio signal; and in response to detecting the spectral stability of the audio signal, copy quantized LPC parameters for the previous frame into the current frame of the audio signal. ### Claim 9 (depends on 8) The electronic device of claim 8, wherein detecting the spectral stability of the audio signal based on at least one of the differential spectrum tilt and the energy difference between the current frame and the previous frame of the audio signal comprises: determining an absolute value of the differential spectrum tilt between the current frame and the previous frame for the audio signal; determining an absolute value of the energy difference between the current frame and the previous frame of the audio signal; and in response to determining that at least one of a change of the absolute value of the differential spectrum tilt and a change of the absolute value of the energy difference has been within a predetermined range for at least a predetermined number of frames, determining that the spectral stability of the audio signal is detected. ### Claim 10 (depends on 8) The electronic device of claim 8, wherein the one or more processors are further configured to: determine that the spectral stability of the audio signal is not detected based on at least one of the differential spectrum tilt and the energy difference between the current frame and the previous frame of the audio signal; and in response to determining that the spectral stability of the audio signal is not detected, perform a quantization on LPC parameters for the current frame to generate quantized LPC parameters for the current frame. ### Claim 11 (depends on 10) The electronic device of claim 10, wherein determining that the spectral stability of the audio signal is not detected based on at least one of the differential spectrum tilt and the energy difference between the current frame and the previous frame of the audio signal comprises at least one of the following: determining an absolute value of the differential spectrum tilt between the current frame and the previous frame for the audio signal; and determining that a change of the absolute value of the differential spectrum tilt has not been within a predetermined range for at least a predetermined number of frames; or determining an absolute value of the energy difference between the current frame and the previous frame of the audio signal; and determining that a change of the absolute value of the energy difference has not been within a predetermined range for at least a predetermined number of frames. ### Claim 12 (depends on 8) The electronic device of claim 8, wherein the one or more processors are further configured to: determine that the quantized LPC parameters has been copied for at least a predetermined number of frames prior to the current frame; and in response to determining that the quantized LPC parameters has been copied for at least the predetermined number of frames prior to the current frame, perform a quantization on LPC parameters for the current frame to generate quantized LPC parameters for the current frame. ### Claim 13 (depends on 8) The electronic device of claim 8, wherein the one or more processors further configured to: send a bit to a decoder indicating that the quantized LPC parameters are copied from the previous frame. ### Claim 14 (depends on 8) The electronic device of claim 8, wherein the one or more processors are further configured to: in response to detecting the spectral stability of the audio signal, perform a quantization on a differential energy level between the current frame and the previous frame to generate a quantized differential energy level; and in response to determining that the spectral stability is not detected, perform a quantization on an energy level of the current frame to generate a quantized energy level of the current frame. ### Claim 15 A non-transitory computer-readable medium storing computer instructions for performing linear predictive coding (LPC) of an audio signal, that when executed by one or more processors, cause the one or more processors to perform operations comprising: determining at least one of a differential spectrum tilt and an energy difference between a current frame and a previous frame of the audio signal; detecting a spectral stability of the audio signal based on at least one of the differential spectrum tilt and the energy difference between the current frame and the previous frame of the audio signal; and in response to detecting the spectral stability of the audio signal, copying quantized LPC parameters for the previous frame into the current frame of the audio signal. ### Claim 16 (depends on 15) The non-transitory computer-readable medium of claim 15, wherein detecting the spectral stability of the audio signal based on at least one of the differential spectrum tilt and the energy difference between the current frame and the previous frame of the audio signal comprises: determining an absolute value of the differential spectrum tilt between the current frame and the previous frame for the audio signal; determining an absolute value of the energy difference between the current frame and the previous frame of the audio signal; and in response to determining that at least one of a change of the absolute value of the differential spectrum tilt and a change of the absolute value of the energy difference has been within a predetermined range for at least a predetermined number of frames, determining that the spectral stability of the audio signal is detected. ### Claim 17 (depends on 15) The non-transitory computer-readable medium of claim 15, wherein the operations further comprise: determining that the spectral stability of the audio signal is not detected based on at least one of the differential spectrum tilt and the energy difference between the current frame and the previous frame of the audio signal; and in response to determining that the spectral stability of the audio signal is not detected, performing a quantization on LPC parameters for the current frame to generate quantized LPC parameters for the current frame. ### Claim 18 (depends on 17) The non-transitory computer-readable medium of claim 17, wherein determining that the spectral stability of the audio signal is not detected based on at least one of the differential spectrum tilt and the energy difference between the current frame and the previous frame of the audio signal comprises at least one of the following: determining an absolute value of the differential spectrum tilt between the current frame and the previous frame for the audio signal; and determining that a change of the absolute value of the differential spectrum tilt has not been within a predetermined range for at least a predetermined number of frames; or determining an absolute value of the energy difference between the current frame and the previous frame of the audio signal; and determining that a change of the absolute value of the energy difference has not been within a predetermined range for at least a predetermined number of frames. ### Claim 19 (depends on 15) The non-transitory computer-readable medium of claim 15, wherein the operations further comprise: determining that the quantized LPC parameters has been copied for at least a predetermined number of frames prior to the current frame; and in response to determining that the quantized LPC parameters has been copied for at least the predetermined number of frames prior to the current frame, performing a quantization on LPC parameters for the current frame to generate quantized LPC parameters for the current frame. ### Claim 20 (depends on 15) The non-transitory computer-readable medium of claim 15, wherein the operations further comprise: sending a bit to a decoder indicating that the quantized LPC parameters are copied from the previous frame.