Multi-channel signal decoding method, computer-readable storage medium, computer program, and decoding device

Abstract

To provide a stereo signal encoding method and device that decrease the number of bits needed for encoding, and a stereo signal decoding method and device.SOLUTION: An encoding method comprises steps of: executing spectrum spreading on a quantize LSF parameter of a primary channel signal in a current frame of a stereo signal so as to obtain a spectrum spread LSF parameter of the primary channel signal (S510); determining a predicted residue of an LSF parameter of a secondary channel signal in the current frame based upon a source LSF parameter of the secondary channel signal and the spectrum spread LSF parameter of the primary channel signal (S520); quantizing the predicted residue of the LSF parameter of the secondary channel signal (S530); and encoding the quantized LSF parameter of the primary channel signal (S540).SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] This application claims priority to Chinese Patent Application No. 201810701919.1, entitled "Stereo signal encoding method and apparatus, and stereo signal decoding method and apparatus," filed with the China Patent Office on June 29, 2018, which is incorporated herein by reference in its entirety.

[0002] The present application relates to the field of audio, and more particularly to a method and apparatus for encoding a stereo signal, and a method and apparatus for decoding a stereo signal. [Background technology]

[0003] In the time-domain stereo encoding / decoding method, the encoder side first performs inter-channel time difference estimation on the stereo signal, performs time alignment based on the estimation result, then performs time-domain downmixing on the time-aligned signal, and finally separately encodes the primary channel signal and secondary channel signal obtained after downmixing to obtain an encoded bitstream.

[0004] Encoding the primary channel signal and the secondary channel signal may include determining linear prediction coefficients (LPCs) for the primary channel signal and the LPCs for the secondary channel signal, converting the LPCs for the primary channel signal and the LPCs for the secondary channel signal into LSF parameters for the primary channel signal and LSF parameters for the secondary channel signal, respectively, and then performing quantization on the LSF parameters for the primary channel signal and the LSF parameters for the secondary channel signal.

[0005] The process of performing quantization on the LSF parameters of the primary channel signal and the LSF parameters of the secondary channel signal may include quantizing the original LSF parameters of the primary channel signal to obtain quantized LSF parameters of the primary channel signal; performing reuse determination based on the distance between the LSF parameters of the primary channel signal and the LSF parameters of the secondary channel signal; determining, if the distance between the LSF parameters of the primary channel signal and the LSF parameters of the secondary channel signal is equal to or greater than a threshold, that the LSF parameters of the secondary channel signal do not satisfy the reuse condition and that the original LSF parameters of the secondary channel signal need to be quantized to obtain the quantized LSF parameters of the secondary channel signal; and writing the quantized LSF parameters of the primary channel signal and the quantized LSF parameters of the secondary channel signal into a bitstream. If the distance between the LSF parameters of the primary channel signal and the LSF parameters of the secondary channel signal is less than the threshold, only the quantized LSF parameters of the primary channel signal are written into the bitstream. In this case, the quantized LSF parameters of the primary channel signal may be used as the quantized LSF parameters of the secondary channel signal.

[0006] In this encoding process, if the LSF parameters of the secondary channel signal do not satisfy the reuse condition, both the quantized LSF parameters of the primary channel signal and the quantized LSF parameters of the secondary channel signal need to be written into the bitstream, which requires a relatively large number of bits for encoding. Summary of the Invention

[0007] The present application provides a stereo signal encoding method and apparatus, and a stereo signal decoding method and apparatus, which help reduce the number of bits required for encoding when the LSF parameters of the secondary channel signal do not satisfy the reuse condition.

[0008] According to a first aspect, the present application provides a stereo signal encoding method, comprising: performing spectrum spreading on quantized LSF parameters of a primary channel signal in a current frame of the stereo signal to obtain spread-spectrum LSF parameters of the primary channel signal; determining prediction residuals of the LSF parameters of the secondary channel signal in the current frame based on original LSF parameters of the secondary channel signal and the spread-spectrum LSF parameters of the primary channel signal; and performing quantization on the prediction residuals of the LSF parameters of the secondary channel signal.

[0009] In the encoding method, spectrum spreading is first performed on the quantized LSF parameters of the primary channel signal, then a prediction residual of the secondary channel signal is determined based on the spectrum spreading LSF parameters and the original LSF parameters of the secondary channel signal, and quantization is performed on the prediction residual. The value of the prediction residual is smaller than the value of the LSF parameters of the secondary channel signal, and the order of magnitude of the value of the prediction residual is smaller than the order of magnitude of the value of the LSF parameters of the secondary channel signal. Therefore, compared with separately performing quantization on the LSF parameters of the secondary channel signal, performing quantization on the prediction residual helps reduce the number of bits required for encoding.

[0010] In relation to the first aspect, in a first possible implementation, the step of performing spectrum spreading on quantized LSF parameters of a primary channel signal in a current frame in a stereo signal to obtain spread-spectrum LSF parameters of the primary channel signal includes the step of performing an average extension process on the quantized LSF parameters of the primary channel signal to obtain the spread-spectrum LSF parameters, wherein the average extension process is performed according to the following equation:

number

[0011] where:

number

number

number

[0012] In relation to the first aspect, in a second possible implementation, the step of performing spectrum spreading on quantized LSF parameters of a primary channel signal in a current frame of a stereo signal to obtain spread-spectrum LSF parameters of the primary channel signal includes the steps of converting the quantized LSF parameters of the primary channel signal into linear prediction coefficients, modifying the linear prediction coefficients to obtain modified linear prediction coefficients of the primary channel signal, and converting the modified linear prediction coefficients of the primary channel signal into LSF parameters, wherein the LSF parameters obtained through the conversion are the spread-spectrum LSF parameters of the primary channel signal.

[0013] In relation to the first aspect, or the first or second possible implementation, in a third possible implementation, the prediction residual of the LSF parameters of the secondary channel signal is the difference between the original LSF parameters of the secondary channel signal and the spread-spectrum LSF parameters of the primary channel signal.

[0014] In relation to the first aspect or the first or second possible implementation, in a fourth possible implementation, the step of determining prediction residuals of the LSF parameters of the secondary channel signal in the current frame based on the original LSF parameters of the secondary channel signal and the spread-spectrum LSF parameters of the primary channel signal includes the steps of performing two-stage prediction on the LSF parameters of the secondary channel signal based on the spread-spectrum LSF parameters of the primary channel signal to obtain predicted LSF parameters of the secondary channel signal, and using the difference between the original LSF parameters and the predicted LSF parameters of the secondary channel signal as the prediction residuals of the secondary channel signal.

[0015] In relation to the first aspect or any one of the above-mentioned possible implementations, in a fifth possible implementation, before the step of determining a prediction residual of the LSF parameters of the secondary channel signal in the current frame based on the original LSF parameters of the secondary channel signal and the spread-spectrum LSF parameters of the primary channel signal, the encoding method further includes a step of determining that the LSF parameters of the secondary channel signal do not satisfy a reuse condition.

[0016] Whether the LSF parameters of the secondary channel signal do not satisfy the reuse condition can be determined according to the prior art, for example, the schemes described in the Background Art.

[0017] According to a second aspect, the present application provides a stereo signal decoding method, comprising the steps of: obtaining quantized LSF parameters of a primary channel signal in a current frame from a bitstream; performing spectrum spreading on the quantized LSF parameters of the primary channel signal to obtain spread-spectrum LSF parameters of the primary channel signal; obtaining prediction residuals of LSF parameters of a secondary channel signal in the current frame of the stereo signal from the bitstream; and determining the quantized LSF parameters of the secondary channel signal based on the prediction residuals of the LSF parameters of the secondary channel signal and the spread-spectrum LSF parameters of the primary channel signal.

[0018] In the decoding method, the quantized LSF parameters of the secondary channel signal may be determined based on the prediction residual of the secondary channel signal and the quantized LSF parameters of the primary channel signal. Therefore, the quantized LSF parameters of the secondary channel signal may not need to be recorded in the bitstream, but the prediction residual of the secondary channel signal is recorded. This helps to reduce the number of bits required for encoding.

[0019] In relation to the second aspect, in a first possible implementation, the step of performing spectrum spreading on quantized LSF parameters of a primary channel signal in a current frame in a stereo signal to obtain spread-spectrum LSF parameters of the primary channel signal includes the step of performing an average extension process on the quantized LSF parameters of the primary channel signal to obtain spread-spectrum LSF parameters of the primary channel signal, where the average extension process is performed according to the following equation:

number

[0020] where:

number

number

number

[0021] In relation to the second aspect, in a second possible implementation, the step of performing spectrum spreading on quantized LSF parameters of a primary channel signal in a current frame of a stereo signal to obtain spread-spectrum LSF parameters of the primary channel signal includes the steps of converting the quantized LSF parameters of the primary channel signal into linear prediction coefficients, modifying the linear prediction coefficients to obtain modified linear prediction coefficients of the primary channel signal, and converting the modified linear prediction coefficients of the primary channel signal into LSF parameters, wherein the LSF parameters obtained through the conversion are the spread-spectrum LSF parameters of the primary channel signal.

[0022] In relation to the second aspect or the first or second possible implementation, in a third possible implementation, the quantized LSF parameters of the secondary channel signal are the sum of spread spectrum LSF parameters and a prediction residual.

[0023] In relation to the second aspect or the first or second possible implementation, in a fourth possible implementation, the step of determining quantized LSF parameters of the secondary channel signal based on prediction residuals of the LSF parameters of the secondary channel signal and the spread-spectrum LSF parameters of the primary channel signal includes a step of performing two-stage prediction on the LSF parameters of the secondary channel signal based on the spread-spectrum LSF parameters of the primary channel signal to obtain predicted LSF parameters, and a step of using the sum of the predicted LSF parameters and the prediction residuals as the quantized LSF parameters of the secondary channel signal.

[0024] According to a third aspect, there is provided a stereo signal coding device, the coding device comprising modules configured to perform the coding method according to the first aspect or any one of the possible implementations of the first aspect.

[0025] According to a fourth aspect, there is provided a stereo signal decoding device, the decoding device comprising modules configured to perform the method according to the second aspect or any one of the possible implementations of the second aspect.

[0026] According to a fifth aspect, there is provided a stereo signal encoding device. The encoding device includes a memory and a processor. The memory is configured to store a program. The processor is configured to execute the program. When the program is executed in the memory, the processor implements the encoding method according to the first aspect or any one of the possible implementations of the first aspect.

[0027] According to a sixth aspect, there is provided a stereo signal decoding device. The decoding device includes a memory and a processor. The memory is configured to store a program. The processor is configured to execute the program. When the program is executed in the memory, the processor implements the decoding method according to the second aspect or any one of the possible implementations of the second aspect.

[0028] According to a seventh aspect, there is provided a computer-readable storage medium storing program code for execution by an apparatus or device, the program code including instructions used to implement the encoding method according to the first aspect or any one of the possible implementations of the first aspect.

[0029] According to an eighth aspect, there is provided a computer-readable storage medium storing program code for execution by an apparatus or device, the program code including instructions used to implement a decoding method according to the second aspect or any one of the possible implementations of the second aspect.

[0030] According to a ninth aspect, there is provided a chip, the chip including a processor and a communication interface, the communication interface configured to communicate with an external device, the processor configured to implement the encoding method according to the first aspect or any one of the possible implementations of the first aspect.

[0031] Optionally, the chip may further include a memory, the memory storing instructions, and the processor configured to execute the instructions stored in the memory, the instructions, when executed, causing the processor to implement the encoding method according to the first aspect or any one of the possible implementations of the first aspect.

[0032] Optionally, the chip may be integrated into a terminal device or a network device.

[0033] According to a tenth aspect, there is provided a chip, the chip including a processor and a communication interface, the communication interface configured to communicate with an external device, the processor configured to implement the decoding method according to the second aspect or any one of the possible implementations of the second aspect.

[0034] Optionally, the chip may further include a memory, the memory storing instructions, and the processor configured to execute the instructions stored in the memory, which, when executed, configures the processor to implement a decoding method according to the second aspect or any one of the possible implementations of the second aspect.

[0035] Optionally, the chip may be integrated into a terminal device or a network device.

[0036] According to an eleventh aspect, embodiments of the present application provide a computer program product comprising instructions which, when run on a computer, enable the computer to perform the encoding method according to the first aspect.

[0037] According to a twelfth aspect, embodiments of the present application provide a computer program product comprising instructions, which when run on a computer enable the computer to perform the decoding method according to the second aspect. [Brief explanation of the drawings]

[0038] [Figure 1] 1 is a schematic structural diagram of a stereo encoding and decoding system in the time domain according to an embodiment of the present application;

[0039] [Figure 2] 1 is a schematic diagram of a mobile terminal according to an embodiment of the present application;

[0040] [Figure 3] FIG. 1 is a schematic diagram of a network element according to an embodiment of the present application;

[0041] [Figure 4] 10 is a schematic flow chart of a method for performing quantization on LSF parameters of a primary channel signal and LSF parameters of a secondary channel signal.

[0042] [Figure 5] 1 is a schematic flow chart of a stereo signal encoding method according to an embodiment of the present application;

[0043] [Figure 6] 1 is a schematic flowchart of a stereo signal encoding method according to an embodiment of the present application;

[0044] [Figure 7] 1 is a schematic flow chart of a stereo signal encoding method according to an embodiment of the present application;

[0045] [Figure 8] 1 is a schematic flow chart of a stereo signal encoding method according to an embodiment of the present application;

[0046] [Figure 9] 1 is a schematic flow chart of a stereo signal encoding method according to an embodiment of the present application;

[0047] [Figure 10] 1 is a schematic flowchart of a stereo signal decoding method according to an embodiment of the present application;

[0048] [Figure 11] 1 is a schematic structural diagram of a stereo signal encoding device according to an embodiment of the present application;

[0049] [Figure 12] 1 is a schematic structural diagram of a stereo signal decoding device according to an embodiment of the present application;

[0050] [Figure 13] FIG. 2 is a schematic structural diagram of a stereo signal encoding apparatus according to another embodiment of the present application;

[0051] [Figure 14] FIG. 2 is a schematic structural diagram of a stereo signal decoding device according to another embodiment of the present application;

[0052] [Figure 15] 3 is a schematic diagram of linear prediction spectral envelopes of a primary channel signal and a secondary channel signal; DETAILED DESCRIPTION OF THE INVENTION

[0053] 1 is a schematic structural diagram of a stereo encoding and decoding system in the time domain according to an exemplary embodiment of the present application. The stereo encoding and decoding system includes an encoding component 110 and a decoding component 120.

[0054] It should be understood that a stereo signal in this application may be an original stereo signal, a stereo signal including two signals included in a signal on multiple channels, or a stereo signal including two signals jointly generated from multiple signals included in a signal on multiple channels.

[0055] The encoding component 110 is configured to encode the stereo signal in the time domain. Optionally, the encoding component 110 may be implemented in the form of software, hardware, or a combination of software and hardware, which is not limited in the embodiment of the present application.

[0056] The encoding component 110 encoding the stereo signal in the time domain may include the following steps.

[0057] (1) Perform time-domain preprocessing on the acquired stereo signal to obtain a time-domain preprocessed left channel signal and a time-domain preprocessed right channel signal.

[0058] The stereo signal may be collected by a collection component and transmitted to an encoding component 110. Optionally, the collection component and the encoding component 110 may be located on the same device. Alternatively, the collection component and the encoding component 110 may be located on different devices.

[0059] The time-domain pre-processed left channel signal and the time-domain pre-processed right channel signal are signals on two channels in the pre-processed stereo signal.

[0060] Optionally, the time-domain pre-processing may include at least one of high-pass filtering, pre-emphasis, sampling rate conversion, and channel switching, which is not limited in the embodiments of the present application.

[0061] (2) Perform time estimation based on the time-domain preprocessed left channel signal and the time-domain preprocessed right channel signal to obtain an inter-channel time difference between the time-domain preprocessed left channel signal and the time-domain preprocessed right channel signal.

[0062] For example, a cross-correlation function between the left channel signal and the right channel signal may be calculated based on the time-domain pre-processed left channel signal and the time-domain pre-processed right channel signal, and then the maximum value of the cross-correlation function is searched for, and the maximum value is used as the inter-channel time difference between the time-domain pre-processed left channel signal and the time-domain pre-processed right channel signal.

[0063] As another example, the cross-correlation function between the left channel signal and the right channel signal may be calculated based on the time-domain pre-processed left channel signal and the time-domain pre-processed right channel signal. Next, based on the cross-correlation function between the left channel signal and the right channel signal in each of L frames (L is an integer equal to or greater than 1) before the current frame, long-term smoothing is performed on the cross-correlation function between the left channel signal and the right channel signal in the current frame to obtain a smoothed cross-correlation function. Then, the maximum value of the smoothed cross-correlation function is searched for, and the index value corresponding to the maximum value is used as the inter-channel time difference between the time-domain pre-processed left channel signal and the time-domain pre-processed right channel signal in the current frame.

[0064] As another example, inter-frame smoothing may be performed on the estimated inter-channel time difference in the current frame based on the inter-channel time difference in M ​​frames (M is an integer greater than or equal to 1) before the current frame, and the smoothed inter-channel time difference is used as the final inter-channel time difference between the time-domain pre-processed left channel signal and the time-domain pre-processed right channel signal in the current frame.

[0065] It should be understood that the above-described inter-channel time difference estimation methods are merely examples, and the embodiments of the present application are not limited to the above-described inter-channel time difference estimation methods.

[0066] (3) performing time alignment of the time-domain preprocessed left channel signal and the time-domain preprocessed right channel signal based on the inter-channel time difference to obtain a time-aligned left channel signal and a time-aligned right channel signal;

[0067] For example, based on the estimated inter-channel time difference in the current frame and the inter-channel time difference in the previous frame, one or two of the left and right channel signals in the current frame may be compressed or expanded so that there is no inter-channel time difference between the time-aligned left channel signal and the time-aligned right channel signal.

[0068] (4) Encode the inter-channel time difference to obtain an inter-channel time difference coding index.

[0069] (5) Calculate stereo parameters for the time-domain downmix, encode the stereo parameters for the time-domain downmix, and obtain encoding indexes of the stereo parameters for the time-domain downmix.

[0070] The stereo parameters for the time-domain downmix are used to perform a time-domain downmix on the time-aligned left channel signal and the time-aligned right channel signal.

[0071] (6) Based on the stereo parameters for the time-domain downmix, perform a time-domain downmix on the time-aligned left channel signal and the time-aligned right channel signal to obtain a primary channel signal and a secondary channel signal.

[0072] The primary channel signal is used to represent inter-channel correlation information and may also be referred to as a downmixed signal or a center channel signal, and the secondary channel signal is used to represent inter-channel difference information and may also be referred to as a residual signal or a side channel signal.

[0073] When the time-aligned left channel signal and the time-aligned right channel signal are aligned in the time domain, the secondary channel signal is weakest, and in this case the stereo signal has the greatest effect.

[0074] (7) Separately encode the primary channel signal and the secondary channel signal to obtain a first mono encoded bitstream corresponding to the primary channel signal and a second mono encoded bitstream corresponding to the secondary channel signal.

[0075] (8) Writing the inter-channel time difference coding index, the stereo parameter coding index, the first mono coded bitstream, and the second mono coded bitstream into a stereo coded bitstream.

[0076] It should be noted that not all of the above steps are essential. For example, step (1) is not essential. If step (1) is not included, the left channel signal and the right channel signal used for time estimation may be the left channel signal and the right channel signal in the original stereo signal. In this specification, the left channel signal and the right channel signal in the original stereo signal are signals obtained after acquisition and analog-to-digital (A / D) conversion.

[0077] The decoding component 120 is configured to decode the stereo encoded bitstream produced by the encoding component 110 to obtain a stereo signal.

[0078] Optionally, encoding component 110 may be connected to decoding component 120 in a wired or wireless manner, and decoding component 120 may obtain the stereo encoded bitstream generated by encoding component 110 through the connection between decoding component 120 and encoding component 110. Alternatively, encoding component 110 may store the generated stereo encoded bitstream in memory, and decoding component 120 reads the stereo encoded bitstream in memory.

[0079] Optionally, the decoding component 120 may be implemented in the form of software, hardware, or a combination of software and hardware, which is not limited in the embodiments of the present application.

[0080] The process by which the decoding component 120 decodes the stereo encoded bitstream to obtain a stereo signal may include the following steps.

[0081] (1) The first mono coded bitstream and the second mono coded bitstream in the stereo coded bitstream are decoded to obtain a primary channel signal and a secondary channel signal.

[0082] (2) Obtain coding indexes of stereo parameters for time-domain upmixing based on the stereo coded bitstream, and perform time-domain upmixing on the primary channel signal and the secondary channel signal to obtain a time-domain upmixed left channel signal and a time-domain upmixed right channel signal.

[0083] (3) Based on the stereo coded bitstream, obtain a coding index of the inter-channel time difference, and perform a running time adjustment on the time-domain upmixed left channel signal and the time-domain upmixed right channel signal to obtain a stereo signal.

[0084] Optionally, the encoding component 110 and the decoding component 120 may be located in the same device or in different devices. The device may be a mobile terminal with voice signal processing capabilities, such as a mobile phone, a tablet computer, a laptop portable computer, a desktop computer, a Bluetooth sound box, a recording pen, or a wearable device, or may be a network element with voice signal processing capabilities in a core network or a wireless network. This is not a limitation in the embodiments of the present application.

[0085] For example, as shown in Figure 2, the following example is used to provide an explanation: The encoding component 110 is located in the mobile terminal 130. The decoding component 120 is located in the mobile terminal 140. The mobile terminal 130 and the mobile terminal 140 are electronic devices independent of each other and capable of processing audio signals. For example, each of the mobile terminal 130 and the mobile terminal 140 may be a mobile phone, a wearable device, a virtual reality (VR) device, an augmented reality (AR) device, etc. In addition, the mobile terminal 130 is connected to the mobile terminal 140 through a wireless or wired network.

[0086] Optionally, the mobile terminal 130 may include a collection component 131, an encoding component 110, and a channel encoding component 132. The collection component 131 is connected to the encoding component 110, and the encoding component 110 is connected to the encoding component 132.

[0087] Optionally, mobile terminal 140 may include an audio playback component 141, a decoding component 120, and a channel decoding component 142. Audio playback component 141 is connected to decoding component 120, and decoding component 120 is connected to channel decoding component 142.

[0088] After collecting the stereo signal using the collection component 131, the mobile terminal 130 encodes the stereo signal using the encoding component 110 to obtain a stereo encoded bitstream. The mobile terminal 130 then encodes the stereo encoded bitstream using the channel encoding component 132 to obtain a transmission signal.

[0089] Mobile terminal 130 sends transmission signals to mobile terminal 140 over a wireless or wired network.

[0090] After receiving the transmission signal, the mobile terminal 140 decodes the transmission signal to obtain a stereo encoded bitstream by using the channel decoding component 142, decodes the stereo encoded bitstream to obtain a stereo signal by using the decoding component 120, and reproduces the stereo signal by using the audio reproduction component 141.

[0091] For example, the description of this embodiment of the present application uses an example in which the encoding component 110 and the decoding component 120 are located in the same network element 150 having voice signal processing capabilities in a core network or a wireless network, as shown in FIG.

[0092] Optionally, network element 150 includes a channel decoding component 151, a decoding component 120, an encoding component 110, and a channel encoding component 152. Channel decoding component 151 is connected to decoding component 120, decoding component 120 is connected to encoding component 110, and encoding component 110 is connected to channel encoding component 152.

[0093] After receiving a transmission signal transmitted by another device, the channel decoding component 151 decodes the transmission signal to obtain a first stereo encoded bitstream. The decoding component 120 decodes the stereo encoded bitstream to obtain a stereo signal. The encoding component 110 encodes the stereo signal to obtain a second stereo encoded bitstream. The channel encoding component 152 encodes the second stereo encoded bitstream to obtain a transmission signal.

[0094] The other device may be a mobile terminal having a voice signal processing capability, or may be another network element having a voice signal processing capability, which is not limited in the embodiments of the present application.

[0095] Optionally, encoding component 110 and decoding component 120 in the network element may transcode the stereo encoded bitstream transmitted by the mobile terminal.

[0096] Optionally, in the embodiment of the present application, the device in which the encoding component 110 is located may be referred to as an audio encoding device. In actual implementation, the audio encoding device may also have an audio decoding function, which is not limited in the embodiment of the present application.

[0097] Optionally, in the embodiment of the present application, only a stereo signal is used as an example for explanation. In the present application, the audio encoding device may further process a multi-channel signal, where the multi-channel signal includes at least two channel signals.

[0098] The encoding component 110 may encode the primary and secondary channel signals by using an algebraic code excited linear prediction (ACELP) coding method.

[0099] An ACELP encoding method typically includes determining LPC coefficients of a primary channel signal and LPC coefficients of a secondary channel signal, converting each of the LPC coefficients of the primary channel signal and the LPC coefficients of the secondary channel signal into LSF parameters and performing quantization on the LSF parameters of the primary channel signal and the LSF parameters of the secondary channel signal, retrieving an adaptive code excitation to determine a pitch period and an adaptive codebook gain and separately performing quantization on the pitch period and the adaptive codebook gain, and retrieving an algebraic code excitation to determine a pulse index and gain of the algebraic code excitation and separately performing quantization on the pulse index and gain of the algebraic code excitation.

[0100] FIG. 4 illustrates an example manner in which encoding component 110 performs quantization on the LSF parameters of the primary channel signal and the LSF parameters of the secondary channel signal.

[0101] S410: Determine original LSF parameters of the primary channel signal based on the primary channel signal.

[0102] S420: Determine original LSF parameters of the secondary channel signal based on the secondary channel signal.

[0103] There is no execution order between steps S410 and S420.

[0104] S430: Determine whether the LSF parameters of the secondary channel signal satisfy a reuse decision condition based on the original LSF parameters of the primary channel signal and the original LSF parameters of the secondary channel signal. The reuse decision condition may also be simply referred to as a reuse condition.

[0105] If the LSF parameters of the secondary channel signal do not satisfy the reuse criterion, step S440 is performed. If the LSF parameters of the secondary channel signal satisfy the reuse criterion, step S450 is performed.

[0106] The reuse means that the quantized LSF parameters of the secondary channel signal can be obtained based on the quantized LSF parameters of the primary channel signal. For example, the quantized LSF parameters of the primary channel signal are used as the quantized LSF parameters of the secondary channel signal. In other words, the quantized LSF parameters of the primary channel signal are reused as the quantized LSF parameters of the secondary channel signal.

[0107] Determining whether the LSF parameters of the secondary channel signal satisfy a reuse decision condition may be referred to as performing reuse decision on the LSF parameters of the secondary channel signal.

[0108] For example, when the reuse determination condition is that the distance between the original LSF parameters of the primary channel signal and the original LSF parameters of the secondary channel signal is equal to or less than a preset threshold, if the distance between the original LSF parameters of the primary channel signal and the original LSF parameters of the secondary channel signal is greater than the preset threshold, it is determined that the LSF parameters of the secondary channel signal do not satisfy the reuse determination condition. Alternatively, if the distance between the original LSF parameters of the primary channel signal and the original LSF parameters of the secondary channel signal is equal to or less than a preset threshold, it may be determined that the LSF parameters of the secondary channel signal satisfy the reuse determination condition.

[0109] It should be understood that the criteria used in the reuse determination described above are merely examples and are not intended to be limiting of the present application.

[0110] The distance between the LSF parameters of the primary channel signal and the LSF parameters of the secondary channel signal may be used to represent the difference between the LSF parameters of the primary channel signal and the LSF parameters of the secondary channel signal.

[0111] The distance between the LSF parameters of the primary channel signal and the LSF parameters of the secondary channel signal can be calculated in several ways.

[0112] For example, the distance between the LSF parameters of the primary channel signal and the LSF parameters of the secondary channel signal

number

number

[0113] where:

number

number

[0114]

number

[0115] Performing a reuse decision on the original LSF parameters of the secondary channel signal may also be referred to as performing a quantization decision on the LSF parameters of the secondary channel signal. If the decision result is to quantize the LSF parameters of the secondary channel signal, the original LSF parameters of the secondary channel signal may be quantized and written into the bitstream to obtain quantized LSF parameters of the secondary channel signal.

[0116] The decision result at this stage can be written into the bitstream and transmitted to the decoder side.

[0117] S440: Quantize the original LSF parameters of the secondary channel signal to obtain quantized LSF parameters of the secondary channel signal, and quantize the LSF parameters of the primary channel signal to obtain quantized LSF parameters of the primary channel signal.

[0118] It should be understood that when the LSF parameters of the secondary channel signal satisfy the reuse criterion, directly using the quantized LSF parameters of the primary channel signal as the quantized LSF parameters of the secondary channel signal is merely an example. Of course, the quantized LSF parameters of the primary channel signal may be reused by other methods to obtain the quantized LSF parameters of the secondary channel signal. This is not limited to this embodiment of the present application.

[0119] S450: If the LSF parameters of the secondary channel signal satisfy the reuse criterion, directly use the quantized LSF parameters of the primary channel signal as the quantized LSF parameters of the secondary channel signal.

[0120] The original LSF parameters of the primary channel signal and the original LSF parameters of the secondary channel signal are separately quantized and written into a bit stream to obtain quantized LSF parameters of the primary channel signal and quantized LSF parameters of the secondary channel signal, which occupy a relatively large number of bits.

[0121] 5 is a schematic flowchart of a stereo signal encoding method according to an embodiment of the present application. If the reuse decision result shows that the reuse decision condition is not satisfied, the encoding component 110 may perform the method shown in FIG.

[0122] S510: Perform spectrum spreading on the quantized LSF parameters of the primary channel signal in the current frame of the stereo signal to obtain spread spectrum LSF parameters of the primary channel signal.

[0123] S520: Determine a prediction residual of the LSF parameters of the secondary channel signal in the current frame based on the original LSF parameters of the secondary channel signal and the spread-spectrum LSF parameters of the primary channel signal.

[0124] As shown in Figure 15, there is a similarity between the linear prediction spectral envelope of the primary channel signal and the linear prediction spectral envelope of the secondary channel signal. The linear prediction spectral envelope is represented by LPC coefficients, and the LPC coefficients can be converted into LSF parameters. Therefore, there is a similarity between the LSF parameters of the primary channel signal and the LSF parameters of the secondary channel signal. Therefore, determining the prediction residual of the LSF parameters of the secondary channel signal based on the spread-spectrum LSF parameters of the primary channel signal helps improve the accuracy of the prediction residual.

[0125] The original LSF parameters of the secondary channel signal may be understood as the LSF parameters obtained based on the secondary channel signal by using a method in the prior art, for example, the original LSF parameters obtained in S420.

[0126] Determining the prediction residual of the LSF parameters of the secondary channel signal based on the original LSF parameters of the secondary channel signal and the predicted LSF parameters of the secondary channel signal may include using a difference between the original LSF parameters of the secondary channel signal and the predicted LSF parameters of the secondary channel signal as the prediction residual of the LSF parameters of the secondary channel signal.

[0127] S530: Quantize the prediction residual of the LSF parameters of the secondary channel signal.

[0128] S540: Perform quantization on the quantized LSF parameters of the primary channel signal.

[0129] In the encoding method of this embodiment of the present application, when the LSF parameters of the secondary channel signal need to be encoded, quantization is performed on the prediction residual of the LSF parameters of the secondary channel signal, which helps reduce the number of bits required for encoding compared to the method in which the LSF parameters of the secondary channel signal are encoded separately.

[0130] In addition, since the LSF parameters of the secondary channel signal used to determine the prediction residual are obtained through prediction based on the LSF parameters obtained after spectrum spreading is performed on the quantized LSF parameters of the primary channel signal, similar characteristics between the linear predicted spectral envelope of the primary channel signal and the linear predicted spectral envelope of the secondary channel signal can be used, which helps to improve the accuracy of the prediction residual compared with the quantized LSF parameters of the primary channel signal and helps to improve the accuracy at the decoder side in determining the quantized LSF parameters of the secondary channel signal based on the prediction residual and the quantized LSF parameters of the primary channel signal.

[0131] S510, S520, and S530 can be implemented in multiple ways, and the following provides an explanation with reference to Figures 6 to 9.

[0132] As shown in FIG. 6, S510 may include S610, and S520 may include S620.

[0133] S610: Perform pull-to-average spread spectrum on the quantized LSF parameters of the primary channel signal to obtain spread spectrum LSF parameters of the primary channel signal.

[0134] The above-mentioned average expansion process can be performed according to the following formula:

number

[0135] where:

number

number

number

[0136] Typically, different linear prediction orders may be used for different coding bandwidths. For example, if the coding bandwidth is 16 KHz, 20th-order linear prediction may be performed, i.e., M=20. If the coding bandwidth is 12.8 KHz, 16th-order linear prediction may be performed, i.e., M=16. The LSF parameter vector may also be simply referred to as LSF parameters.

[0137] The spreading factor β may be a preset constant. For example, β may be a preset real constant greater than 0 and less than 1. For example, β=0.82 or β=0.91.

[0138] Alternatively, the spreading factor β may be adaptively obtained. For example, different spreading factors β may be preset based on coding parameters such as different coding modes, coding bandwidths, or coding rates, and then the corresponding spreading factor β is selected based on one or more current coding parameters. The coding modes described herein may include voice activation detection results, distinction between unvoiced and voiced sounds, etc.

[0139] For example, the following corresponding spreading factors β may be set for different coding rates:

number

[0140] Here, brate represents the coding rate.

[0141] Then, the spreading factor corresponding to the coding rate in the current frame may be determined based on the coding rate in the current frame and the above-mentioned correspondence relationship between the coding rate and the spreading factor.

[0142] The mean vector of the LSF parameters of the secondary channel signal may be obtained through training based on a large amount of data, may be a preset constant vector, or may be obtained adaptively.

[0143] For example, different mean vectors of the LSF parameters of the secondary channel signal may be preset based on coding parameters such as a coding mode, a coding bandwidth, or a coding rate, etc. Then, the mean vector corresponding to the LSF parameters of the secondary channel signal is selected based on the coding parameters in the current frame.

[0144] S620: Use the difference between the original LSF parameters of the secondary channel signal and the spread spectrum LSF parameters of the primary channel signal as a prediction residual of the LSF parameters of the secondary channel signal.

[0145] Specifically, the prediction residual of the LSF parameters of the secondary channel signal satisfies the following equation:

number

[0146] where:

number

number

number

[0147] In other words, the spread-spectrum LSF parameters of the primary channel signal are directly used as the predicted LSF parameters of the secondary channel signal (this implementation is referred to as performing single-stage prediction on the LSF parameters of the secondary channel signal), and the difference between the original LSF parameters of the secondary channel signal and the predicted LSF parameters of the secondary channel signal may be used as the prediction residual of the LSF parameters of the secondary channel signal.

[0148] As shown in FIG. 7, S510 may include S710, and S520 may include S720.

[0149] S710: Perform average stretching spread spectrum on the quantized LSF parameters of the primary channel signal to obtain spread spectrum LSF parameters of the primary channel signal.

[0150] Please refer to S610 for this step, and the details will not be repeated here.

[0151] S720: Based on the spread-spectrum LSF parameters of the primary channel signal, perform multi-stage prediction on the LSF parameters of the secondary channel signal to obtain predicted LSF parameters of the secondary channel signal, and use the difference between the original LSF parameters of the secondary channel signal and the predicted LSF parameters of the secondary channel signal as a prediction residual of the secondary channel signal.

[0152] The particular number of times prediction is performed on the LSF parameters of the secondary channel signal may be referred to as the particular number of stages of prediction performed on the LSF parameters of the secondary channel signal.

[0153] The multi-stage prediction may include predicting spread-spectrum LSF parameters of the primary channel signal as predicted LSF parameters of the secondary channel signal, which may be referred to as intra-prediction.

[0154] Intra prediction can be performed at any position in multi-stage prediction. For example, intra prediction (i.e., stage 1 prediction) can be performed first, and then predictions other than intra prediction (e.g., stage 2 prediction and stage 3 prediction) can be performed. Alternatively, predictions other than intra prediction (i.e., stage 1 prediction) can be performed first, and then intra prediction (i.e., stage 2 prediction) can be performed. Of course, predictions other than intra prediction (i.e., stage 3 prediction) can also be performed.

[0155] When two-stage prediction is performed on the LSF parameters of the secondary channel signal and the stage 1 prediction is intra prediction, the stage 2 prediction may be performed based on the intra prediction result of the LSF parameters of the secondary channel signal (i.e., based on the spread-spectrum LSF parameters of the primary channel signal) or based on the original LSF parameters of the secondary channel signal. For example, the stage 2 prediction may be performed on the LSF parameters of the secondary channel signal by using an inter prediction method based on the quantized LSF parameters of the secondary channel signal in the previous frame and the original LSF parameters of the secondary channel signal in the current frame.

[0156] When two-stage prediction is performed on the LSF parameters of the secondary channel signal, where the stage 1 prediction is intra prediction and the stage 2 prediction is performed based on the spread-spectrum LSF parameters of the primary channel signal, the prediction residual of the LSF parameters of the secondary channel satisfies the following equation:

number

number

[0157] where:

number

number

number

number

number

[0158] When two-stage prediction is performed on the LSF parameters of the secondary channel signal, where the stage 1 prediction is intra prediction and the stage 2 prediction is performed based on the original LSF parameter vector of the secondary channel signal, the prediction residual of the LSF parameters of the secondary channel signal satisfies the following equation:

number

number

[0159] where:

number

number

number

number

number

[0160] As shown in FIG. 8, S510 may include S810, S820, and S830, and S520 may include S840.

[0161] S810: Convert the quantized LSF parameters of the primary channel signal into linear prediction coefficients.

[0162] For details on converting LSF parameters into linear prediction coefficients, please refer to the prior art. The details will not be described here. The linear prediction coefficients obtained after converting the quantized LSF parameters of the primary channel signal into linear prediction coefficients are α i and the transfer function used for the transformation is denoted as A(z), then the following equation is satisfied:

number

[0163] where α i are the linear prediction coefficients obtained after converting the quantized LSF parameters of the primary channel signal into linear prediction coefficients, and M is the linear prediction rank.

[0164] S820: Modify the linear prediction coefficients to obtain modified linear prediction coefficients of the primary channel signal.

[0165] The transfer function of the modified linear predictor satisfies the following equation:

number

[0166] where α i are the linear prediction coefficients obtained after converting the quantized LSF parameters of the primary channel signal into linear prediction coefficients, β is the spreading factor, and M is the linear prediction rank.

[0167] The spread spectrum linear prediction coefficients of the primary channel signal satisfy the following equation:

number

number

[0168] where a i are the linear prediction coefficients obtained after converting the quantized LSF parameters of the primary channel signal into linear prediction coefficients,

number

[0169] For the method of obtaining the spreading factor β in this implementation, please refer to the method of obtaining the spreading factor β in S610, and the details will not be described again here.

[0170] S830: Convert the modified linear prediction coefficients of the primary channel signal into LSF parameters, where the LSF parameters obtained through the conversion are spread spectrum LSF parameters of the primary channel signal.

[0171] The method for converting linear prediction coefficients into LSF parameters is described in the prior art, and is not described in detail here. The spread spectrum LSF parameters of the primary channel signal are

number

[0172] S840: Use the difference between the original LSF parameters of the secondary channel signal and the spread spectrum LSF parameters of the primary channel signal as a prediction residual of the LSF parameters of the secondary channel signal.

[0173] For this step, please refer to S620, and the details will not be repeated here.

[0174] As shown in FIG. 9, S510 may include S910, S920, and S930, and S520 may include S940.

[0175] S910: Convert the quantized LSF parameters of the primary channel signal into linear prediction coefficients.

[0176] Please refer to S810 for this step, and the details will not be repeated here.

[0177] S920: Modify the linear prediction coefficients to obtain modified linear prediction coefficients of the primary channel signal.

[0178] Please refer to S820 for this step, and the details will not be repeated here.

[0179] S930: Convert the modified linear prediction coefficients of the primary channel signal into LSF parameters, where the LSF parameters obtained through the conversion are spread spectrum LSF parameters of the primary channel signal.

[0180] Please refer to S830 for this step, and the details will not be repeated here.

[0181] S940: Based on the spread-spectrum LSF parameters of the primary channel signal, perform multi-stage prediction on the LSF parameters of the secondary channel signal to obtain predicted LSF parameters of the secondary channel signal, and use the difference between the original LSF parameters of the secondary channel signal and the predicted LSF parameters of the secondary channel signal as a prediction residual of the secondary channel signal.

[0182] Please refer to S720 for this step, and the details will not be repeated here.

[0183] In S530 in this embodiment of the present application, when quantization is performed on the prediction residual of the LSF parameters of the secondary channel signal, any LSF parameter vector quantization method in the prior art may be referred to, for example, split vector quantization, multi-stage vector quantization, or safe-net vector quantization.

[0184] The vector obtained after quantizing the prediction residual of the LSF parameters of the secondary channel signal is

number

number

[0185] where:

number

number

number

[0186] 10 is a schematic flowchart of a stereo signal decoding method according to an embodiment of the present application. If the reuse decision result shows that the reuse condition is not satisfied, the decoding component 120 may execute the method shown in FIG.

[0187] S1010: Obtain the quantized LSF parameters of the primary channel signal in the current frame from the bitstream.

[0188] This step is described in the prior art and will not be described in detail here.

[0189] S1020: Perform spectrum spreading on the quantized LSF parameters of the primary channel signal to obtain spread spectrum LSF parameters of the primary channel signal.

[0190] Please refer to S510 for this step, and the details will not be repeated here.

[0191] S1030: Obtain prediction residuals of LSF parameters of a secondary channel signal in a current frame of a stereo signal from a bitstream.

[0192] For this step, please refer to the implementation method for obtaining arbitrary parameters of a stereo signal from a bitstream in the prior art, and the details will not be described here.

[0193] S1040: Determine quantized LSF parameters of the secondary channel signal based on the prediction residual of the LSF parameters of the secondary channel signal and the spread-spectrum LSF parameters of the primary channel signal.

[0194] In the decoding method according to the embodiment of the present application, the quantized LSF parameters of the secondary channel signal can be determined based on the prediction residual of the LSF parameters of the secondary channel signal, which helps to reduce the number of bits occupied by the LSF parameters of the secondary channel signal in the bitstream.

[0195] In addition, since the quantized LSF parameters of the secondary channel signal are determined based on the LSF parameters obtained after spectrum spreading is performed on the quantized LSF parameters of the primary channel signal, similar characteristics between the linear predicted spectral envelope of the primary channel signal and the linear predicted spectral envelope of the secondary channel signal can be used, which helps to improve the accuracy of the quantized LSF parameters of the secondary channel signal.

[0196] In some possible implementations, performing spectrum spreading on the quantized LSF parameters of the primary channel signal in the current frame in the stereo signal to obtain the spread-spectrum LSF parameters of the primary channel signal includes performing an average extension process on the quantized LSF parameters of the primary channel signal to obtain the spread-spectrum LSF parameters, where the average extension process may be performed according to the following equation:

number

[0197] where:

number

number

number

[0198] In a possible implementation, the step of performing spectrum spreading on quantized LSF parameters of a primary channel signal in a current frame of the stereo signal to obtain spread-spectrum LSF parameters of the primary channel signal includes the steps of converting the quantized LSF parameters of the primary channel signal into linear prediction coefficients, modifying the linear prediction coefficients to obtain modified linear prediction coefficients of the primary channel signal, and converting the modified linear prediction coefficients of the primary channel signal into LSF parameters, wherein the LSF parameters obtained through the conversion are the spread-spectrum LSF parameters of the primary channel signal.

[0199] In some possible implementations, the quantized LSF parameters of the secondary channel signal are the sum of the spread-spectrum LSF parameters of the primary channel signal and a prediction residual of the LSF parameters of the secondary channel signal.

[0200] In some possible implementations, the step of determining quantized LSF parameters of the secondary channel signal based on prediction residuals of the LSF parameters of the secondary channel signal and the spread-spectrum LSF parameters of the primary channel signal may include: performing two-stage prediction on the LSF parameters of the secondary channel signal based on the spread-spectrum LSF parameters of the primary channel signal to obtain predicted LSF parameters; and using the sum of the predicted LSF parameters and the prediction residuals of the LSF parameters of the secondary channel signal as the quantized LSF parameters of the secondary channel signal.

[0201] In this implementation, for the implementation of performing two-stage prediction on the LSF parameters of the secondary channel signal based on the spread spectrum LSF parameters of the primary channel signal to obtain predicted LSF parameters, please refer to S720, and the details will not be described again here.

[0202] 11 is a schematic block diagram of a stereo signal encoding device 1100 according to an embodiment of the present application. It should be understood that the encoding device 1100 is merely an example.

[0203] In some implementations, the spread spectrum module 1110 , the decision module 1120 , and the quantization module 1130 may all be included in the encoding component 110 of the mobile terminal 130 or in the network element 150 .

[0204] The spread spectrum module 1110 is configured to perform spread spectrum on the quantized line spectral frequency LSF parameters of the primary channel signal in a current frame in the stereo signal to obtain spread spectrum LSF parameters of the primary channel signal.

[0205] The determination module 1120 is configured to determine a prediction residual of the LSF parameters of the secondary channel signal in the current frame based on the original LSF parameters of the secondary channel signal and the spread-spectrum LSF parameters of the primary channel signal.

[0206] The quantization module 1130 is configured to perform quantization on the prediction residual.

[0207] Optionally, the spread spectrum module is configured to perform an average extension process on the quantized LSF parameters of the primary channel signal to obtain spread spectrum LSF parameters, where the average extension process may be performed according to the following equation:

number

[0208] where:

number

number

number

[0209] Optionally, the spread-spectrum module may be specifically configured to convert the quantized LSF parameters of the primary channel signal into linear prediction coefficients, modify the linear prediction coefficients to obtain modified linear prediction coefficients of the primary channel signal, and convert the modified linear prediction coefficients of the primary channel signal into LSF parameters, where the LSF parameters obtained through conversion are spread-spectrum LSF parameters of the primary channel signal.

[0210] Optionally, the prediction residual of the secondary channel signal is the difference between the original LSF parameters of the secondary channel signal and the spread spectrum LSF parameters.

[0211] Optionally, the determination module may be specifically configured to perform two-stage prediction on the LSF parameters of the secondary channel signal based on the spread-spectrum LSF parameters of the primary channel signal to obtain predicted LSF parameters of the secondary channel signal, and use the difference between the original LSF parameters of the secondary channel signal and the predicted LSF parameters as a prediction residual of the secondary channel signal.

[0212] Before determining the prediction residual of the LSF parameters of the secondary channel signal in the current frame based on the original LSF parameters of the secondary channel signal and the spread-spectrum LSF parameters of the primary channel signal, the determination module is further configured to determine that the LSF parameters of the secondary channel signal do not satisfy a reuse condition.

[0213] The encoding device 1100 may be configured to perform the encoding method illustrated in Figure 5. For the sake of brevity, the details will not be described again here.

[0214] 12 is a schematic block diagram of a stereo signal decoding device 1200 according to an embodiment of the present application. It should be understood that the decoding device 1200 is merely an example.

[0215] In some implementations, the acquisition module 1220 , the spread spectrum module 1230 , and the decision module 1240 may all be included in the decoding component 120 of the mobile terminal 140 or the network element 150 .

[0216] The obtaining module 1220 is configured to obtain the quantized LSF parameters of the primary channel signal in the current frame from the bitstream.

[0217] The spread spectrum module 1230 is configured to perform spread spectrum on the quantized LSF parameters of the primary channel signal to obtain spread spectrum LSF parameters of the primary channel signal.

[0218] The obtaining module 1220 is further configured to obtain, from the bitstream, a prediction residual of the line spectral frequency LSF parameters of the secondary channel signal in the current frame of the stereo signal.

[0219] The determination module 1240 is configured to determine the quantized LSF parameters of the secondary channel signal based on the prediction residual of the LSF parameters of the secondary channel signal and the spread-spectrum LSF parameters of the primary channel signal.

[0220] Optionally, the spread spectrum module specifically comprises: It may be configured to perform an average extension process on the quantized LSF parameters of the primary channel signal to obtain spread spectrum LSF parameters, and the average extension process may be performed according to the following equation:

number

[0221] where:

number

number

number

[0222] Optionally, the spread-spectrum module may be specifically configured to convert the quantized LSF parameters of the primary channel signal into linear prediction coefficients, modify the linear prediction coefficients to obtain modified linear prediction coefficients of the primary channel signal, and convert the modified linear prediction coefficients of the primary channel signal into LSF parameters, where the LSF parameters obtained through conversion are spread-spectrum LSF parameters of the primary channel signal.

[0223] Optionally, the quantized LSF parameters of the secondary channel signal are the sum of spread spectrum LSF parameters and a prediction residual.

[0224] Optionally, the determination module may be specifically configured to: perform two-stage prediction on the LSF parameters of the secondary channel signal based on the spread-spectrum LSF parameters of the primary channel signal to obtain predicted LSF parameters; and use the sum of the predicted LSF parameters and the prediction residual as the quantized LSF parameters of the secondary channel signal.

[0225] Before obtaining the prediction residual of the line spectral frequency LSF parameters of the secondary channel signal in the current frame of the stereo signal from the bitstream, the obtaining module is further configured to determine that the LSF parameters of the secondary channel signal do not satisfy a reuse condition.

[0226] The decoding device 1200 may be configured to perform the decoding method illustrated in Figure 10. For the sake of brevity, the details will not be described again here.

[0227] 13 is a schematic block diagram of a stereo signal encoding device 1300 according to an embodiment of the present application. It should be understood that the encoding device 1300 is merely an example.

[0228] The memory 1310 is configured to store a program.

[0229] The processor 1320 is configured to execute a program stored in the memory. When the program in the memory is executed, the processor is configured to perform spread spectrum on quantized line spectral frequency LSF parameters of the primary channel signal in a current frame of the stereo signal to obtain spread spectrum LSF parameters of the primary channel signal, determine prediction residuals of the LSF parameters of the secondary channel signal in the current frame based on the original LSF parameters of the secondary channel signal and the spread spectrum LSF parameters of the primary channel signal, and perform quantization on the prediction residuals.

[0230] Optionally, the processor 1320 may be specifically configured to perform an average extension process on the quantized LSF parameters of the primary channel signal to obtain spread-spectrum LSF parameters, and the average extension process may be performed according to the following equation:

number

[0231] where:

number

number

number

[0232] Optionally, the processor may be specifically configured to convert the quantized LSF parameters of the primary channel signal into linear prediction coefficients, modify the linear prediction coefficients to obtain modified linear prediction coefficients of the primary channel signal, and convert the modified linear prediction coefficients of the primary channel signal into LSF parameters, where the LSF parameters obtained through conversion are spread-spectrum LSF parameters of the primary channel signal.

[0233] Optionally, the prediction residual of the secondary channel signal is the difference between the original LSF parameters of the secondary channel signal and the spread spectrum LSF parameters.

[0234] Optionally, the processor may be specifically configured to perform two-stage prediction on the LSF parameters of the secondary channel signal based on the spread-spectrum LSF parameters of the primary channel signal to obtain predicted LSF parameters of the secondary channel signal, and to use the difference between the original LSF parameters of the secondary channel signal and the predicted LSF parameters as a prediction residual of the secondary channel signal.

[0235] Before determining the prediction residual of the LSF parameters of the secondary channel signal in the current frame based on the original LSF parameters of the secondary channel signal and the spread-spectrum LSF parameters of the primary channel signal, the processor is further configured to determine that the LSF parameters of the secondary channel signal do not satisfy a reuse condition.

[0236] The encoding device 1300 may be configured to perform the encoding method illustrated in Figure 5. For the sake of brevity, the details will not be described again here.

[0237] 14 is a schematic block diagram of a stereo signal decoding device 1400 according to an embodiment of the present application. It should be understood that the decoding device 1400 is merely an example.

[0238] The memory 1410 is configured to store a program.

[0239] Processor 1420 is configured to execute a program stored in memory that, when executed, configures the processor to: obtain quantized LSF parameters of a primary channel signal in a current frame from the bitstream, perform spectrum spreading on the quantized LSF parameters of the primary channel signal to obtain spread-spectrum LSF parameters of the primary channel signal, obtain prediction residuals of line spectral frequency LSF parameters of a secondary channel signal in a current frame of the stereo signal from the bitstream, and determine the quantized LSF parameters of the secondary channel signal based on the prediction residuals of the LSF parameters of the secondary channel signal and the spread-spectrum LSF parameters of the primary channel signal.

[0240] Optionally, the processor specifically: It may be configured to perform an average extension process on the quantized LSF parameters of the primary channel signal to obtain spread spectrum LSF parameters, and the average extension process may be performed according to the following equation:

number

[0241] where:

number

number

number

[0242] Optionally, the processor may be specifically configured to convert the quantized LSF parameters of the primary channel signal into linear prediction coefficients, modify the linear prediction coefficients to obtain modified linear prediction coefficients of the primary channel signal, and convert the modified linear prediction coefficients of the primary channel signal into LSF parameters, where the LSF parameters obtained through conversion are spread-spectrum LSF parameters of the primary channel signal.

[0243] Optionally, the quantized LSF parameters of the secondary channel signal are the sum of the spread-spectrum LSF parameters of the primary channel signal and a prediction residual.

[0244] Optionally, the processor may be specifically configured to perform two-stage prediction on the LSF parameters of the secondary channel signal based on the spread-spectrum LSF parameters of the primary channel signal to obtain predicted LSF parameters, and use the sum of the predicted LSF parameters and the prediction residual as the quantized LSF parameters of the secondary channel signal.

[0245] Before obtaining the prediction residual of the line spectral frequency LSF parameters of the secondary channel signal in the current frame of the stereo signal from the bitstream, the processor is further configured to determine that the LSF parameters of the secondary channel signal do not satisfy a reuse condition.

[0246] The decoding device 1400 may be configured to perform the decoding method described in Figure 10. For the sake of brevity, the details will not be described again here.

[0247] Those skilled in the art will recognize that, by combining the examples described in the embodiments disclosed herein, the units and algorithm steps can be implemented by electronic hardware or a combination of computer software and electronic hardware. Whether these functions are implemented by hardware or software depends on the specific application and the design constraints of the technical solution. Those skilled in the art may use different methods to implement the described functions for each specific application, but this implementation example should not be considered to go beyond the scope of this application.

[0248] For the purpose of convenience and simplicity of description, those skilled in the art can clearly understand, for the detailed operation processes of the aforementioned systems, devices and units, please refer to the corresponding processes in the aforementioned method embodiments, and the details will not be described again here.

[0249] In some embodiments provided herein, it should be understood that the disclosed systems, devices, and methods may be implemented in other ways. For example, the described device embodiments are merely examples. For example, the division into units is merely a logical division of functions. In actual implementation, there may be other division schemes. For example, multiple units or components may be combined or integrated into another system, and some functions may be ignored or not performed. Furthermore, the shown or described mutual couplings or direct couplings or communication connections may be implemented using some interfaces. Indirect couplings or communication connections between multiple devices or multiple units may be implemented in electronic, mechanical, or other forms.

[0250] The units described as separate parts may or may not be physically separate, and the parts shown as units may or may not be physical units, may be located in one location, or may be distributed across multiple network units, and some or all of these units may be selected based on actual requirements to achieve the objectives of the solutions of these embodiments.

[0251] Additionally, the functional units in the embodiments of the present application may be integrated into a single processing unit, each of which may exist physically alone, or two or more of which may be integrated into a single unit.

[0252] It should be understood that the processor in embodiments of the present application may be a central processing unit (CPU). The processor may alternatively be another general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), or another programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, etc. The general-purpose processor may be a microprocessor, or the processor may be any conventional processor, etc.

[0253] When a function is implemented in the form of a software functional unit and sold or used as an independent product, the function may be stored in a computer-readable storage medium. Based on this understanding, essentially, the technical solution of the present application, or a portion contributing to the prior art, or a part of the technical solution may be implemented in the form of a software product. The computer software product is stored in a storage medium and includes some instructions for instructing a computer device (which may be a personal computer, a server, or a network device) to perform all or some steps of the method described in the embodiments of the present application. The above-mentioned storage medium includes any medium capable of storing program code, such as a USB flash drive, a removable hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or a compact disk.

[0254] The above description is merely a specific implementation example of the present application and is not intended to limit the protection scope of the present application. Any modifications or replacements that can be easily conceived by those skilled in the art within the technical scope disclosed in the present application shall fall within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims. Other possible claims (Item 1) 1. A method for encoding a stereo signal, comprising the steps of: performing spread spectrum on the quantized line spectral frequency LSF parameters of the primary channel signal in the current frame of the stereo signal to obtain spread spectrum LSF parameters of the primary channel signal; determining a prediction residual of LSF parameters of a secondary channel signal in the current frame based on original LSF parameters of a secondary channel signal and spread-spectrum LSF parameters of the primary channel signal; performing quantization on the prediction residual; A method for providing (Item 2) The step of performing spectrum spreading on the quantized line spectrum frequency LSF parameters of the primary channel signal in the current frame of the stereo signal to obtain the spread spectrum LSF parameters of the primary channel signal includes: performing an average extension process on the quantized LSF parameters of the primary channel signal to obtain the spread spectrum LSF parameters; and the average extension process is based on the following formula:

number

number

number

number

number

number

number

number

number

number

number

number

number

number

number

number

Claims

1. 1. A method for decoding a multi-channel signal, comprising: receiving a bitstream having quantized line spectral frequency (LSF) parameters of a primary channel signal in a current frame of a multi-channel signal including at least two channel signals; parsing the bitstream to obtain the quantized LSF parameters of the primary channel signal; obtaining spread spectrum LSF parameters of the primary channel signal based on the quantized LSF parameters of the primary channel signal; obtaining a prediction residual of LSF parameters in a secondary channel signal of the current frame; obtaining quantized LSF parameters of the secondary channel signal based on the prediction residual of the LSF parameters of the secondary channel signal and the spread-spectrum LSF parameters of the primary channel signal; obtaining a reconstructed multi-channel signal of the current frame based on the quantized LSF parameters of the secondary channel signal; Equipped with obtaining the spread spectrum LSF parameters of the primary channel signal based on the quantized LSF parameters of the primary channel signal, obtaining a mean vector of the original LSF parameters of the secondary channel signal; obtaining spread spectrum LSF parameters of the primary channel signal based on the average vector; 1. A method for decoding a multi-channel signal, comprising:

2. obtaining the spread spectrum LSF parameters of the primary channel signal based on the quantized LSF parameters of the primary channel signal, obtaining a spreading factor, the spreading factor being greater than 0 and less than 1; obtaining a vector of the quantized LSF parameters of the primary channel signal; and 2. The method for decoding a multi-channel signal according to claim 1, wherein in the step of obtaining spread-spectrum LSF parameters of the primary channel signal based on the mean vector, the spread-spectrum LSF parameters of the primary channel signal are obtained based on the spreading factor, the mean vector, and the vector of the quantized LSF parameters of the primary channel signal.

3. obtaining spread spectrum LSF parameters of the primary channel signal based on the spreading factor, the mean vector, and the vector of the quantized LSF parameters of the primary channel signal, [Equation 1] obtaining the spread spectrum LSF parameters of the primary channel signal according to LSF SB represents the vector of the spread spectrum LSF parameters of the primary channel signal; LSF Ｐ (i) represents the vector of the quantized LSF parameters of the primary channel signal; i represents the vector index, β represents the diffusivity, 0<β<1, [Equation 4] 3. The method of decoding a multi-channel signal according to claim 2, wherein i represents the mean vector, 1≦i≦M, i is an integer, and M represents a linear prediction rank.

4. 1. A method for decoding a multi-channel signal, comprising: receiving a bitstream having quantized line spectral frequency (LSF) parameters of a primary channel signal in a current frame of a multi-channel signal including at least two channel signals; parsing the bitstream to obtain the quantized LSF parameters of the primary channel signal; obtaining spread spectrum LSF parameters of the primary channel signal based on the quantized LSF parameters of the primary channel signal; obtaining a prediction residual of LSF parameters in a secondary channel signal of the current frame; obtaining quantized LSF parameters of the secondary channel signal based on the prediction residual of the LSF parameters of the secondary channel signal and the spread-spectrum LSF parameters of the primary channel signal; obtaining a reconstructed multi-channel signal of the current frame based on the quantized LSF parameters of the secondary channel signal; Equipped with obtaining the spread spectrum LSF parameters of the primary channel signal based on the quantized LSF parameters of the primary channel signal, converting the quantized LSF parameters of the primary channel signal into linear prediction coefficients; obtaining modified linear prediction coefficients of the primary channel signal based on the linear prediction coefficients; converting the modified linear prediction coefficients of the primary channel signal into the spread spectrum LSF parameters of the primary channel signal; 1. A method for decoding a multi-channel signal, comprising:

5. The method for decoding a multi-channel signal according to claim 1 , wherein the quantized LSF parameters of the secondary channel signal are a sum of the spread-spectrum LSF parameters of the primary channel signal and the prediction residual.

6. The step of obtaining the quantized LSF parameters of the secondary channel signal comprises: performing two-stage prediction on the LSF parameters of the secondary channel signal based on the spread-spectrum LSF parameters of the primary channel signal to obtain predicted LSF parameters; obtaining a sum of the predicted LSF parameters and the prediction residual, the sum representing the quantized LSF parameters of the secondary channel signal; Method for decoding a multi-channel signal according to any one of claims 1 to 4, comprising:

7. A computer-readable storage medium storing a program for causing a computer to execute the method for decoding a multi-channel signal according to any one of claims 1 to 6.

8. A computer program product that causes a computer to execute the method for decoding a multi-channel signal according to any one of claims 1 to 6.

9. Memory and 7. An apparatus for decoding a stereo signal, comprising: at least one processor coupled to said memory and configured to perform the method for decoding a multi-channel signal according to any one of claims 1 to 6.

Images