US-20260129400-A1 - Multi-Channel Signal Encoding Method, Multi-Channel Signal Decoding Method, Encoder, and Decoder

US20260129400A1US 20260129400 A1US20260129400 A1US 20260129400A1US-20260129400-A1

Abstract

A multi-channel signal encoding method includes determining a downmixed signal of a first channel signal and a second channel signal in a multi-channel signal, and reverberation gain parameters corresponding to different subbands of the first channel signal and the second channel signal, where the obtained reverberation gain parameters belong to at least two reverberation gain parameter groups. The method further includes selecting, from the at least two reverberation gain parameter groups, a target reverberation gain parameter group. The method further includes generating parameter indication information, where the parameter indication information indicates the target reverberation gain parameter group. The method further includes encoding reverberation gain parameters corresponding to the target reverberation gain parameter group, the parameter indication information, and the downmixed signal to obtain a bitstream.

Inventors

Zexin LIU
Lei Miao

Assignees

HUAWEI TECHNOLOGIES CO., LTD.

Dates

Publication Date: 20260507
Application Date: 20260105
Priority Date: 20170412

Claims (20)

1 . A method, comprising: determining a downmixed signal of a first channel signal and a second channel signal in a multi-channel signal, wherein the first channel signal and the second channel signal comprise frequency bands, wherein the frequency bands comprise subbands, and wherein the subbands comprise frequency bins; determining reverberation gain parameters corresponding to the subbands; determining, based on at least one of a first coherence between a first energy of the first channel signal or a second energy of the downmixed signal and a second coherence between a third energy of the second channel signal and the second energy, a target reverberation gain parameter to be encoded in the reverberation gain parameters by: determining a difference value between the third energy and the second energy across the frequency bins, wherein the difference value comprises a sum of absolute values of energy differences at each of the frequency bins; and determining that one of the reverberation gain parameters corresponding to a first subband of the subbands of a first frequency band of the frequency bands is the target reverberation gain parameter when the difference value is greater than a threshold; generating parameter indication information indicating the first subband; and encoding the target reverberation gain parameter, the parameter indication information, and the downmixed signal to generate a bitstream.
2 . The method of claim 1 , wherein a first frequency range of the first frequency band is less than a second frequency range of a second frequency band of the frequency bands different from the first frequency band in the first channel signal and the second channel signal.
3 . The method of claim 1 , wherein the frequency bins are in a second frequency band of each of the first channel signal and the second channel signal, and wherein a first frequency range of the second frequency band is greater than a second frequency range of another frequency band, different from the second frequency band, in the first channel signal and the second channel signal.
4 . The method of claim 1 , further comprising determining, based on the first energy and the third energy, the second energy.
5 . An encoder, comprising: a memory configured to store instructions; and a processor coupled to the memory and configured to execute the instructions to cause the encoder to: determine a downmixed signal of a first channel signal and a second channel signal in a multi-channel signal, wherein the first channel signal and the second channel signal comprise frequency bands, wherein the frequency bands comprise subbands, and wherein the subbands comprise frequency bins; determine reverberation gain parameters corresponding to the subbands; determine, based on at least one of a first coherence between a first energy of the first channel signal or a second energy of the downmixed signal and a second coherence between a third energy of the second channel signal and the second energy, a target reverberation gain parameter to be encoded in the reverberation gain parameters by: determining a difference value between the third energy and the second energy across the frequency bins, wherein the difference value comprises a sum of absolute values of energy differences at each of the frequency bins; and determining that one of the reverberation gain parameters corresponding to a first subband of the subbands of a first frequency band of the frequency bands is the target reverberation gain parameter when the difference value is greater than a threshold; generate parameter indication information indicating the first subband; and encode the target reverberation gain parameter, the parameter indication information, and the downmixed signal to generate a bitstream.
6 . The encoder of claim 5 , wherein a first frequency range of the first frequency band is less than a second frequency range of a second frequency band different from the first frequency band in the first channel signal and the second channel signal.
7 . The encoder of claim 5 , wherein the frequency bins are in a second frequency band of each of the first channel signal and the second channel signal, and wherein a first frequency range of the second frequency band is greater than a second frequency range of another frequency band, different from the second frequency band, in the first channel signal and the second channel signal.
8 . The encoder of claim 5 , wherein the processor is further configured to execute the instructions to cause the encoder to determine, based on the first energy and the third energy, the second energy.
9 . A computer program product comprising instructions that are for storage on a non-transitory computer-readable medium and that, when executed by a processor, cause an apparatus to: determine a downmixed signal of a first channel signal and a second channel signal in a multi-channel signal, wherein the first channel signal and the second channel signal comprise frequency bands, wherein the frequency bands comprise subbands, and wherein the subbands comprise frequency bins; determine reverberation gain parameters corresponding to the subbands; determine, based on at least one of a first coherence between a first energy of the first channel signal or a second energy of the downmixed signal and a second coherence between a third energy of the second channel signal and the second energy, a target reverberation gain parameter that needs to be encoded in the reverberation gain parameters by: determining a difference value between the third energy and the second energy across the frequency bins, wherein the difference value comprises a sum of absolute values of energy differences at each of the frequency bins; and determining that one of the reverberation gain parameters corresponding to a first subband of the subbands of a first frequency band of the frequency bands is the target reverberation gain parameter when the difference value is greater than a threshold; generate parameter indication information indicating the first subband; and encode the target reverberation gain parameter, the parameter indication information, and the downmixed signal to generate a bitstream.
10 . The computer program product of claim 9 , wherein a first frequency range of the first frequency band is less than a second frequency range of a second frequency band different from the first frequency band in the first channel signal and the second channel signal.
11 . The computer program product of claim 9 , wherein the frequency bins are in a second frequency band of each of the first channel signal and the second channel signal, and wherein a first frequency range of the second frequency band is greater than a second frequency range of another frequency band, different from the second frequency band, in the first channel signal and the second channel signal.
12 . The computer program product of claim 9 , wherein the instructions, when executed by the processor, further cause the apparatus to determine, based on the first energy and the third energy, the second energy.
13 . The computer program product of claim 9 , wherein the instructions, when executed by the processor, further cause the apparatus to quantize the target reverberation gain parameter prior to encoding the target reverberation gain parameter.
14 . The computer program product of claim 9 , wherein the first frequency band is a low frequency band.
15 . The computer program product of claim 9 , wherein the downmixed signal is a wideband signal.
16 . The computer program product of claim 9 , wherein the downmixed signal is an ultra-wideband signal.
17 . The computer program product of claim 9 , wherein the first channel signal is a left-channel signal, and wherein the second channel signal is a right-channel signal.
18 . The computer program product of claim 9 , wherein the instructions, when executed by the processor, further cause the apparatus to further determine the difference value using inter-frame smoothed energy values.
19 . The computer program product of claim 9 , wherein the threshold is a preset value.
20 . The computer program product of claim 9 , wherein the parameter indication information comprises a plurality of flag bits, and wherein each of the plurality of flag bits corresponds to a respective one of the subbands.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This is a continuation of U.S. patent application Ser. No. 18/493,319 filed on Oct. 24, 2023, which is a continuation of U.S. patent application Ser. No. 17/504,080 filed on Oct. 18, 2021, now U.S. Pat. No. 11,832,087, which is a continuation of U.S. patent application Ser. No. 17/033,026 filed on Sep. 25, 2020, now U.S. Pat. No. 11,178,505, which is a continuation of U.S. patent application Ser. No. 16/601,104 filed on Oct. 14, 2019, now U.S. Pat. No. 10,827,297, which is a continuation of International Patent Application No. PCT/CN2018/077790 filed on Mar. 1, 2018, which claims priority to Chinese Patent Application No. 201710236773.3 filed on Apr. 12, 2017. All of the aforementioned patent applications are hereby incorporated by reference in their entireties. TECHNICAL FIELD This application relates to the audio encoding field, and more specifically, to a multi-channel signal encoding method, a multi-channel signal decoding method, an encoder, and a decoder. BACKGROUND As living quality is improved, people have increasing demands on high-quality audio. Compared with mono audio, stereo audio provides a sense of orientation and a sense of distribution for each sound source, and provides improved clarity, intelligibility, and on-site feeling of sound. Therefore, stereo audio is very popular. Stereo processing technologies mainly include mid/side (MS) encoding, intensity stereo (IS) encoding, and parametric stereo (PS) encoding. In other approaches, when the PS encoding is used to encode a multi-channel signal, an encoder side needs to calculate a reverberation gain parameter corresponding to each subband of a channel signal, and encode the reverberation gain parameter corresponding to each subband of the channel signal, so that a decoder side can perform reverberation processing on each subband of the channel signal based on the reverberation gain parameter corresponding to each subband of the channel signal. However, a relatively large quantity of bits need to be occupied for encoding the reverberation gain parameter corresponding to each subband of the channel signal, and in some cases, performing reverberation processing on each subband of the channel signal causes a worse auditory effect. SUMMARY This application provides a multi-channel signal encoding method, a multi-channel signal decoding method, an encoder, and a decoder, to improve encoding efficiency. According to a first aspect, a multi-channel signal encoding method is provided, where the method includes determining a downmixed signal of a first channel signal and a second channel signal in a multi-channel signal, and reverberation gain parameters corresponding to different subbands of the first channel signal and the second channel signal, determining a target reverberation gain parameter that needs to be encoded in the reverberation gain parameters corresponding to the different subbands of the first channel signal and the second channel signal, generating parameter indication information, where the parameter indication information is used to indicate a subband corresponding to the target reverberation gain parameter, and encoding the target reverberation gain parameter, the parameter indication information, and the downmixed signal to generate a bitstream. In this application, when the first channel signal and the second channel signal are being encoded, reverberation gain parameters corresponding to only some subbands of the first channel signal and the second channel signal may be encoded. Compared with a manner in other approaches in which reverberation gain parameters corresponding to all subbands of the first channel signal and the second channel signal need to be encoded, bit overheads can be reduced to some extent, and encoding efficiency can be improved. Further, a quantity of saved bits may be used to encode another parameter or allocate more bits to the downmixed signal if reverberation gain parameters corresponding to some subbands are encoded, thereby improving overall encoding performance. With reference to the first aspect, in some implementations of the first aspect, the determining a target reverberation gain parameter that needs to be encoded in the reverberation gain parameters corresponding to the different subbands of the first channel signal and the second channel signal includes determining the target reverberation gain parameter based on at least one of energy of the first channel signal and energy of the second channel signal, an inter-channel coherence (IC) between the first channel signal and the second channel signal, energy of the downmixed signal, and an inter-channel level difference (ILD) between the first channel signal and the second channel signal. Coherence between the first channel signal and the second channel signal can be determined based on the energy of the channel signal or the energy of the downmixed signal, the IC, the ILD, and the like, and target reverberat