CN114143699B

CN114143699B - Audio signal processing method and device and computer readable storage medium

Info

Publication number: CN114143699B
Application number: CN202111274850.7A
Authority: CN
Inventors: 刘阳; 刘长滔
Original assignee: Beijing QIYI Century Science and Technology Co Ltd
Current assignee: Beijing QIYI Century Science and Technology Co Ltd
Priority date: 2021-10-29
Filing date: 2021-10-29
Publication date: 2023-11-10
Anticipated expiration: 2041-10-29
Also published as: CN114143699A

Abstract

The invention provides an audio signal processing method, an audio signal processing device and a computer readable storage medium, and belongs to the field of audio and video enhancement. The method comprises the following steps: determining a standard opening angle corresponding to a multichannel surround sound signal to be processed and a loudspeaker opening angle of the playing equipment, wherein the multichannel surround sound signal comprises a left side signal and a right side signal; based on the standard opening angle and the loudspeaker opening angle, carrying out down-mixing enhancement processing on the left side signal and the right side signal to obtain a target left channel signal and a target right channel signal; and outputting the target left channel signal and the target right channel signal through a loudspeaker of the playback device respectively. The invention can break through the limitation of the opening angle of the loudspeaker of the external device to the sound field, widens the sound field of the audio signal output by the external device, ensures that the processed audio signal can present an omnibearing surrounding sound field through the external device, increases the space sense of the audio signal output by the external device, and improves the surrounding sound effect.

Description

Audio signal processing method and device and computer readable storage medium

Technical Field

The present invention relates to audio signal processing methods, apparatuses, and computer readable storage media, and particularly to an audio signal processing method, apparatus, and computer readable storage media.

Background

Multi-channel surround sound is now widely used, wherein 5.1-channel surround sound is the International Telecommunications Union (ITU) recommended surround sound standard. Compared with binaural stereo, the overall sound field of multichannel surround sound can present an omnidirectional spatial sense, which can give the listener a sense of presence in the sound field.

To completely present the surround sound field of the multi-channel surround sound, a certain number of speakers are often required, and the placement positions of the speakers are required to meet a certain condition. However, most audio playback devices, such as smart televisions and notebook computers, often have only one pair of speakers, and only can play back two channel signals of multi-channel surround sound, so that an omnidirectional surround sound field cannot be presented.

Existing schemes typically mix multichannel surround sound into a binaural signal for presentation by an playback device. However, in practical applications, the speaker opening angle of the playback device is often smaller than the standard surround opening angle, and the smaller the opening angle, the narrower the presented sound field. The mixed stereo signal is output through the loudspeaker of the external device, and the finally presented sound field is limited, so that the omnibearing space sense cannot be presented, and the surrounding sound effect is poor.

Disclosure of Invention

The invention provides an audio signal processing method, an audio signal processing device and a computer readable storage medium, so as to solve the problems that after a stereo signal is mixed by multichannel surround sound, a finally presented sound field is limited and cannot present an omnibearing space sense and the surround sound effect is poor after the stereo signal is output through a loudspeaker of external playing equipment to a certain extent.

According to a first aspect of the present invention, there is provided an audio signal processing method applied to an external device including at least two speakers, the method comprising:

determining a standard opening angle corresponding to a multichannel surround sound signal to be processed and a loudspeaker opening angle of the playing equipment, wherein the multichannel surround sound signal comprises a left side signal and a right side signal;

based on the standard opening angle and the loudspeaker opening angle, carrying out down-mixing enhancement processing on the left side signal and the right side signal to obtain a target left channel signal and a target right channel signal;

and outputting the target left channel signal and the target right channel signal through a loudspeaker of the playback device respectively.

According to a second aspect of the present invention, there is provided an audio signal processing apparatus for use in a playback device including at least two speakers, the apparatus comprising:

The opening angle determining module is used for determining a standard opening angle corresponding to a multichannel surround sound signal to be processed and a loudspeaker opening angle of the playing device, wherein the multichannel surround sound signal comprises a left side signal and a right side signal;

the downmix enhancement processing module is used for carrying out downmix enhancement processing on the left side signal and the right side signal based on the standard opening angle and the loudspeaker opening angle to obtain a target left channel signal and a target right channel signal;

and the signal output module is used for respectively outputting the target left channel signal and the target right channel signal through a loudspeaker of the playing device.

According to a third aspect of the present invention, there is provided a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the audio signal processing method according to any of the first aspects.

Aiming at the prior art, the invention has the following advantages:

when the stereo signals are mixed by the multichannel surround sound signals, the standard opening angle corresponding to the multichannel surround sound signals to be processed and the opening angle of the loudspeaker of the external device are determined, wherein the multichannel surround sound signals comprise left side signals and right side signals; then, based on the standard opening angle and the loudspeaker opening angle, carrying out down-mixing enhancement processing on the left side signal and the right side signal to obtain a target left channel signal and a target right channel signal, wherein the target left channel signal and the target right channel signal are left channel signals and right channel signals corresponding to the mixed stereo signal; finally, the target left channel signal and the target right channel signal are respectively output through a loudspeaker of the playback device. Compared with the prior art, the method and the device directly perform mixing processing on the multichannel surround sound signals to obtain stereo signals, the method and the device perform downmixing enhancement processing on the left side signals in the multichannel surround sound signals based on the multichannel surround sound signals and the loudspeaker opening angles of the external device, so that the virtual opening angles are consistent with the standard opening angles of the multichannel surround sound signals after the processed target left channel signals and the target right channel signals are output through the external device, the limitation of the loudspeaker opening angles of the external device on sound fields is broken through, the sound fields of the audio signals output by the external device are widened, the processed audio signals can present an omnibearing surround sound field through the external device, the spatial sense of the audio signals output by the external device is increased, and the surround sound effect is improved.

The foregoing description is only an overview of the present invention, and is intended to be implemented in accordance with the teachings of the present invention in order that the same may be more clearly understood and to make the same and other objects, features and advantages of the present invention more readily apparent.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to designate like parts throughout the figures. In the drawings:

fig. 1 is a flowchart of steps of an audio signal processing method according to an embodiment of the present invention;

FIG. 2 is a schematic view of an opening angle according to an embodiment of the present invention;

FIG. 3 is a flow chart of a process of an audio signal according to an embodiment of the present invention;

fig. 4 is a block diagram of an audio signal processing apparatus according to an embodiment of the present invention.

Detailed Description

Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

The audio signal processing method provided by the embodiment of the invention is applied to a scene of outputting a multichannel surround sound signal through the playback equipment. The playback device includes at least two speakers. The external device may include, but is not limited to, a sound box, etc., an intelligent home device (including an intelligent sound box, a television, a voice assistant, etc.), an intelligent terminal (including an intelligent mobile phone, a video phone, a tablet computer, a conference desktop intelligent terminal, etc.), a movie hall audio playing device, a vehicle-mounted device, a multimedia computer, etc.

Compared with binaural stereo, multichannel surround sound can present an omnidirectional sound field, which can give the listener a sense of presence in it. To completely present the surround sound field of the multi-channel surround sound, a certain number of speakers are often required, and the placement positions of the speakers are required to meet a certain condition. However, most audio playback devices, such as smart televisions and notebook computers, often have only one pair of speakers, and only can play back two channel signals of multi-channel surround sound, so that an omnidirectional surround sound field cannot be presented. In the prior art, a multichannel surround sound signal is typically mixed with a binaural stereo signal, and then output through an playback device. However, the mixed binaural signal presents a limited sound field and poor surround sound due to the limitations of the speaker opening angle of the playback device.

In order to break through the limitation of the opening angle of a loudspeaker of the external device on a sound field and improve the surround sound effect, the invention provides an audio signal processing method.

Referring to fig. 1, a flowchart illustrating steps of an audio signal processing method according to an embodiment of the present invention is shown, where, as shown in fig. 1, the method may include:

step 101, determining a standard opening angle corresponding to a multichannel surround sound signal to be processed and a loudspeaker opening angle of the playback device, wherein the multichannel surround sound signal comprises a left side signal and a right side signal.

And 102, performing down-mixing enhancement processing on the left side signal and the right side signal based on the standard opening angle and the loudspeaker opening angle to obtain a target left channel signal and a target right channel signal.

And 103, respectively outputting the target left channel signal and the target right channel signal through a loudspeaker of the playing device.

It should be noted that, in the embodiment of the present invention, the multi-channel surround sound signal at least includes a left signal, a right signal, and a bass channel signal. For example, the multi-channel surround sound signal in the embodiment of the present invention may be 2.1 channel surround sound, including a left channel signal, a right channel signal, and a bass channel signal; or 3.1 path surround sound including a left path signal, a right path signal, a center path signal, and a bass path signal; alternatively, 5.1 path surround sound, including a left path signal, a right path signal, a center path signal, a left surround path signal, a right surround path signal, and a bass path signal, and so forth. Wherein if the multi-path surround sound signal is 2.1 path surround sound, 3.1 path surround sound, the left side signal comprises a left path signal and the right side signal comprises a right path signal; if the multi-channel surround sound signal is a 5.1-channel surround sound signal, the left side signal includes a left channel signal and a left surround channel signal, and the right side signal includes a right surround channel signal.

The opening angle is the included angle between the speakers at the two sides of the external device and the listener. Referring to fig. 2, a schematic view of an opening angle is shown. As shown in fig. 2, a speaker is respectively arranged at the left side and the right side, and an included angle θ formed by the two speakers and the listener is the opening angle of the speaker of the external device.

The standard opening angle corresponding to the multichannel surround sound signal is the standard included angle between a pair of speakers and a listener defined in the configuration standard of the multichannel surround sound signal. In the embodiment of the invention, the standard opening angle corresponding to the multichannel surround sound signal, in particular to the included angle between a left speaker for outputting a left signal, a right speaker for outputting a right signal and a listener in the configuration standard of the multichannel surround sound signal.

If the left signal is a left channel signal and the right signal is a right channel signal, the standard opening angle is an included angle between a left speaker for outputting the left channel signal, a right speaker for outputting the right channel signal, and a listener. If the left signal includes a left channel signal and a left surround channel signal, the right signal includes a right channel signal and a right surround channel signal, two standard opening angles are respectively a first standard opening angle corresponding to the left channel signal and the right channel signal, and a second standard opening angle corresponding to the left surround channel signal and the right surround channel signal. Taking 5.1-channel surround sound as an example, the first standard opening angle is an included angle between a left front speaker for outputting a left-channel signal, a right front speaker for outputting a right-channel signal, and a listener; the second standard opening angle is an included angle between a left rear speaker for outputting a left surround channel signal, a right rear speaker for outputting a right surround channel signal, and a listener.

For each multi-channel surround sound signal, the standard opening angle is fixed, taking 5.1-channel surround sound as an example, and the first standard opening angle, namely the standard opening angle corresponding to the left channel signal and the right channel signal, is 60 degrees; the second standard opening angle, namely the standard opening angle corresponding to the left surrounding channel signal and the right surrounding channel signal, is 240 degrees.

The audio signal processing method provided by the present invention will be described below by taking the left signal as a left channel signal and the right signal as a right channel signal as an example.

According to the principle of synthetic localization of sound sources, the sound field synthesized by the loudspeakers on both sides of the listener is typically distributed over two loudspeakers and the area between them. The distribution area of the sound field is limited by the opening angle of the loudspeaker, and the larger the opening angle of the loudspeaker is, the wider the distribution area of the sound field is; the smaller the angle of the loudspeaker opening, the narrower the distribution area of the sound field. In practical applications, the opening angle of the speaker of the external device is often smaller than the standard opening angle of the multichannel surround sound, so that the distribution area of the actual sound field generated by the audio signal output by the external device is smaller than the distribution area of the sound field generated by the multichannel surround sound signal, and the omnibearing surround sound field cannot be displayed, and the surround sound effect is poor. Therefore, in the embodiment of the invention, based on the standard opening angle of the multichannel surround sound signal and the opening angle of the loudspeaker of the playback device, the left side signal and the right side signal in the multichannel surround sound signal are subjected to the downmix enhancement processing, and the spatial information is added in the finally generated target left channel signal and target right channel signal, so that the sound fields generated by the target left channel signal and the target right channel signal output by the loudspeaker of the playback device are basically consistent with the sound fields generated by the multichannel surround sound signal, thereby improving the surround sound effect.

The target left channel signal generated in the present invention is a left channel signal of a binaural signal, and the target right channel signal is a right channel signal of the binaural signal. The target left channel signal is output through the left speaker of the playback device and the target right channel signal is output through the right speaker of the playback device, so that a surround sound field similar to multi-channel surround sound can be presented.

Optionally, the downmix enhancement process includes a stereo widening process, or the downmix enhancement process includes a stereo widening process and a signal equalizing process. The stereo widening processing is used for widening sound fields generated by the left side signal and the right side signal, so that the widened sound fields are matched with sound fields generated by the multichannel surround sound signals. The signal equalization processing is used for equalizing the signals subjected to the stereo widening processing, so that abrupt change of the signals subjected to the stereo widening processing is avoided, and the hearing is prevented from being influenced.

The sound field generated by the audio signal is limited by the corresponding opening angle of the audio signal, in other words, stereo widening processing is performed on the left side signal and the right side signal, which is mainly used for adding virtual opening angles to the left side signal and the right side signal, so that the opening angles corresponding to the processed left side signal and right side signal are consistent with the standard opening angle of the multichannel surround sound signal. For example, assuming that the opening angle θ corresponding to the left side signal and the right side signal is 30 °, and the standard opening angle of the multi-channel surround sound signal is 60 °, it is necessary to increase the virtual opening angle for the left side signal and the right side signal by stereo widening processing to 30 °, so that the opening angle θ' corresponding to the processed left side signal and right side signal is 60 °.

In the actual signal processing process, the sound field or the opening angle corresponding to the audio signal is difficult to be directly changed, and the aim of stereo widening can be achieved by processing parameters influencing the sound field or the opening angle. For example, stereo widening processing may be performed on the left-side signal and the right-side signal based on binaural sound pressures generated by the audio signals before and after processing.

In an optional embodiment of the present invention, the downmix enhancement processing includes stereo widening processing, and step 102 performs downmix enhancement processing on the left side signal and the right side signal based on the standard opening angle and the speaker opening angle to obtain a target left channel signal and a target right channel signal, including:

step S11, calculating a first binaural sound pressure corresponding to the multichannel surround sound signal according to the standard opening angle;

step S12, stereo widening processing is carried out on the left side signal and the right side signal based on the opening angle of the loudspeaker and the first binaural sound pressure, and a target left channel signal and a target right channel signal are obtained; and the second binaural sound pressure generated by the target left channel signal and the target right channel signal is the same as the first binaural sound pressure.

Wherein the sound pressure is the variation of the pressure of the medium, namely the pressure P in the medium when a sound field exists and the pressure P in the medium when no sound field exists ₀ And (3) a difference. The binaural sound pressure comprises left ear sound pressure P generated by audio signals output by a left speaker _L And a right ear sound pressure P generated by an audio signal output from a right speaker _R 。

Sound pressure is related to sound field in medium, and the sound field is limited by opening angle, and in same medium, opening angle and binaural sound pressure are in one-to-one correspondence for audio signals output by same pair of speakers. Therefore, in the embodiment of the present invention, the first binaural sound pressure corresponding to the multi-channel surround sound signal, that is, the left ear sound pressure P generated by the left side signal of the multi-channel surround sound signal, may be calculated according to the standard opening angle of the multi-channel surround sound signal _L And a right ear sound pressure P generated by a right side signal of the multi-path surround sound signal _R 。

Then, speaker based on external deviceAnd carrying out stereo widening processing on the left side signal and the right side signal by using the opening angle and the first binaural sound pressure, so that the second binaural sound pressure generated by the generated target left channel signal and target right channel signal is the same as the first binaural sound pressure. That is, the left ear sound pressure P 'generated by the target left channel signal' _L Sound pressure P of left ear generated by the left side signal _L The same, and, to cause the target right channel signal to produce a right ear sound pressure P' _R Sound pressure P of right ear generated by the right side signal _R The same applies.

In the same medium, the sound pressures generated by the two audio signals at a certain position are the same, meaning that the sound fields corresponding to the two audio signals at the same position are the same. Therefore, the embodiment of the invention performs stereo widening processing on the left side signal and the right side signal of the multichannel surround sound signal, so that the second binaural sound pressure generated by the finally generated target left channel signal and target right channel signal is the same as the first binaural sound pressure corresponding to the multichannel surround sound signal. In other words, the sound fields generated by the target left channel signal and the target right channel signal are the same as those generated by the left side signal and the right side signal, so that the limitation of the opening angle of the loudspeaker of the external device on the sound fields is broken through, the sound field of the audio signal output by the external device is widened, the processed audio signal can show an omnibearing surrounding sound field through the external device, the spatial sense of the audio signal output by the external device is increased, and the surrounding sound effect is improved.

In an optional embodiment of the present invention, step S12 of performing stereo widening processing on the left signal and the right signal based on the speaker opening angle and the first binaural sound pressure to obtain a target left channel signal and a target right channel signal includes:

A11, determining a first head related transfer function and a second head related transfer function corresponding to the opening angle of the loudspeaker, wherein the first head related transfer function is a same-side ear head related transfer function, and the second head related transfer function is a different-side ear head related transfer function;

step A12, determining an inverse matrix of a symmetric matrix of the first head related transfer function and the second head related transfer function;

and A13, performing time domain convolution processing on the inverse matrix and the first binaural sound pressure to obtain a target left channel signal and a target right channel signal, so that second binaural sound pressure generated by the target left channel signal and the target right channel signal is the same as the first binaural sound pressure corresponding to the multichannel surround sound signal.

It should be noted that, each opening angle corresponds to a set of head related transfer functions, which are the same-side ear head related transfer function and the different-side ear head related transfer function, respectively. The head related transfer function corresponding to the opening angle may be directly extracted from the head related transfer function database.

Assuming that the first head related transfer function corresponding to the opening angle of the loudspeaker is H' _LL And H' _RR The second head related transfer function is H' _LR And H' _RL Wherein H' _LL ＝H' _RR ，H' _RL ＝H' _RL . Recording the target left channel signal after stereo widening processing as L 'and the target right channel signal as R', outputting the target left channel signal and the target right channel signal through a loudspeaker of the playing device, and generating second double-ear sound pressure, namely, left-ear sound pressure P 'generated by the target left channel signal' _L And a right ear sound pressure P 'generated from the target right channel signal' _R Can be expressed as:

wherein,a symmetric matrix for the first head related transfer function and the second head related transfer function.

Assuming that the left side signal and the right side signal are output through standard opening angles corresponding to the multi-channel surround sound signals, the generated sound pressure of the left ear is P _L Sound pressure of right ear is P _R . In an embodiment of the present invention, the target left channel signal and the target right channel signalThe second binaural sound pressure generated by the number is the same as the first binaural sound pressure corresponding to the multi-channel surround sound, namely P' _L ＝P _L ，P' _R ＝P _R . Then, the target left channel signal L 'and the target right channel signal R' can be expressed as:

it should be noted that the above formula (2) is a frequency domain operation formula, and the inverse matrix of the symmetric matrix of the first head related transfer function and the second head related transfer function and the first binaural sound pressure are subjected to frequency domain multiplication processing, that is, matrix calculation, according to the above formula (2) And matrix->A target left channel signal and a target right channel signal can be obtained.

And (3) performing time domain convolution processing on the inverse matrix of the symmetric matrix of the first head related transfer function and the second head related transfer function corresponding to the time domain and the first binaural sound pressure to obtain a target left channel signal and a target right channel signal.

As can be seen from the above formula (1), the sound pressure may also be directly calculated based on the head related transfer function, so in the embodiment of the present invention, when the stereo widening processing is performed on the left signal and the right signal, the stereo widening processing may also be performed on the left signal and the right signal directly based on the head related transfer function corresponding to the standard opening angle of the multichannel surround signal.

step A21, determining a first head related transfer function and a second head related transfer function corresponding to the opening angle of the loudspeaker, wherein the first head related transfer function is a same-side ear head related transfer function, and the second head related transfer function is a different-side ear head related transfer function;

Step A22, determining a third head related transfer function and a fourth head related transfer function corresponding to the standard opening angle, wherein the third head related transfer function is a same-side ear head related transfer function, and the fourth head related transfer function is a different-side ear head related transfer function;

step A23, calculating a target filter coefficient according to the first head related transfer function, the second head related transfer function, the third head related transfer function and the fourth head related transfer function, wherein the target filter coefficient is used for determining information to be stretched corresponding to the left side signal and the right side signal;

and step A24, filtering the left side signal and the right side signal based on the target filter coefficient to obtain a target left channel signal and a target right channel signal, wherein the second binaural sound pressure generated by the target left channel signal and the target right channel signal is the same as the first binaural sound pressure corresponding to the multichannel surround sound signal.

Assuming that the third head related transfer function corresponding to the standard opening angle is H _LL And H _RR The fourth head related transfer function is H _LR And H _RL . Wherein H is _LL ＝H _RR ，H _LR ＝H _RL . The first binaural sound pressure corresponding to the multichannel surround sound signal, i.e. the left ear sound pressure P generated by the left side signal L _L And a right ear sound pressure P generated by the right side signal R _R Can be expressed as:

and because of P' _L ＝P _L ，P' _R ＝P _R Then, the target left channel signal L' andthe target right channel signal R' can be expressed as:

as can be seen from the above formula (4), the stereo widening process is performed on the left side signal and the right side signal under the condition that the first binaural sound pressure and the second binaural sound pressure are ensured to be the same, and the stereo widening process is essentially based on a matrix formed by the head related transfer functions corresponding to the standard opening anglesAnd a matrix of head related transfer functions corresponding to the opening angles of the loudspeakers>And filtering the left side signal and the right side signal, wherein the target filter coefficient is:

in an alternative embodiment of the present invention, the calculating, in step a23, the target filter coefficient according to the first head related transfer function, the second head related transfer function, the third head related transfer function, and the fourth head related transfer function includes:

a substep a231 of determining an inverse of a first symmetric matrix corresponding to the first head related transfer function and the second head related transfer function;

a sub-step A232 of determining a second symmetric matrix corresponding to the third head related transfer function and the fourth head related transfer function;

Step A233, calculating the product of the inverse matrix of the first symmetric matrix and the second symmetric matrix to obtain a target filter coefficient; the target filter coefficient is a symmetric matrix formed by the same-side filter coefficient and different-side filter coefficient.

And (3) performing matrix operation on the formula (5) and simplifying the formula, wherein the target filter coefficient can be expressed as follows:

wherein,

due to H _LL ＝H _RR ，H _LR ＝H _RL Therefore G _L (θ _L ,f)＝G _R (θ _R ,f)，G _L (θ _R ,f)＝G _R (θ _L F). Wherein G is _L (θ _L F) and G _R (θ _R F) is the ipsilateral filter coefficient, G _L (θ _R F) and G _R (θ _L F) is the ipsilateral filter coefficient.

The left side signal and the right side signal of the multi-channel surround sound signal are filtered based on the target filter coefficient expressed by the above formula (6), so that the target left channel signal and the target right channel signal can be obtained.

In an optional embodiment of the present invention, the filtering processing of the left signal and the right signal based on the target filter coefficient in step a24 to obtain a target left channel signal and a target right channel signal includes:

a sub-step P11 of performing filtering processing on the left signal based on the same-side filtering coefficient and the different-side filtering coefficient respectively to obtain a first left signal and a second left signal, wherein the first left signal corresponds to the same-side filtering coefficient, and the second left signal corresponds to the different-side filtering coefficient;

A sub-step P12 of performing filtering processing on the right-side signal based on the same-side filtering coefficient and the different-side filtering coefficient respectively to obtain a first right-side signal and a second right-side signal, wherein the first right-side signal corresponds to the same-side filtering coefficient, and the second right-side signal corresponds to the different-side filtering coefficient;

a sub-step P13 of performing superposition processing on the first left-side signal and the second right-side signal to obtain a target left channel signal;

and a substep P14, performing superposition processing on the second left-side signal and the first right-side signal to obtain a target right channel signal.

The left signal L and the right signal R are filtered based on the target filter coefficient expressed by the above formula (6), and the obtained target left channel signal L 'and target right channel signal R' may be expressed as:

performing matrix operation on the above formula (7), the target left channel signal L 'and the target right channel signal R' can be expressed as:

L'＝G _L (θ _L ,f)L+G _L (θ _R ,f)R (8)

R'＝G _R (θ _L ,f)L+G _R (θ _R ,f)R (9)

wherein G is _L (θ _L F) and G _R (θ _R F) is the ipsilateral filter coefficient, G _L (θ _R F) and G _R (θ _L F) is an outlier filter coefficient, and G _L (θ _L ,f)＝G _R (θ _R ,f)，G _L (θ _R ,f)＝G _R (θ _L ,f)。

The left side signal is filtered based on the same side filter coefficient and the different side filter coefficient respectively, so as to obtain a first left side signal G _L (θ _L F) L and a second left signal G _R (θ _L ,f)L。

The right side signal is filtered based on the same side filter coefficient and the different side filter coefficient respectively, so as to obtain a first right side signal G _R (θ _R F) R and a second right signal G _L (θ _R ,f)R。

As can be seen from the above formula (8) and formula (9), to obtain the target left channel signal L 'and the target right channel signal R', further superposition processing needs to be performed on the filtered first left signal, first right signal, second left signal, and second right signal. Specific: and performing superposition processing on the first left side signal and the second right side signal to obtain a target left channel signal, and performing superposition processing on the second left side signal and the first right side signal to obtain a target right channel signal.

It should be noted that, in the embodiment of the present invention, the downmix enhancement processing may include a signal equalization processing in addition to a stereo widening processing. The signal equalization processing is used for equalizing the signals subjected to the stereo widening processing, so that abrupt change of the signals subjected to the stereo widening processing is avoided, the hearing is influenced, the tone and color fidelity and the contrast of the audio signals are improved, and the overall hearing is improved.

In an optional embodiment of the present invention, the downmix enhancement processing includes stereo widening processing and signal equalization processing, and step 102 performs the downmix enhancement processing on the left side signal and the right side signal based on the standard opening angle and the speaker opening angle to obtain a target left channel signal and a target right channel signal, including:

step S21, carrying out stereo widening processing on the left side signal and the right side signal based on the standard opening angle and the loudspeaker opening angle to obtain a widened third left channel signal and a widened third right channel signal;

and S22, carrying out signal equalization processing on the third left channel signal and the third right channel signal to obtain a target left channel signal and a target right channel signal.

The signal equalization processing is performed after the stereo widening processing: firstly, carrying out stereo widening processing on the left side signal and the right side signal to obtain a third left channel signal and a third right channel signal; and then, carrying out signal equalization processing on the third left channel signal and the third right channel signal to obtain a target left channel signal and a target right channel signal. The stereo widening processing may be performed on the left signal and the right signal in any manner as described above, and further description of the embodiments of the present invention is omitted herein. In addition, the specific implementation mode of the signal equalization processing is not limited, so long as abrupt changes of the signals after the stereo widening processing can be avoided, and the tone quality of the target left channel signal and the tone quality of the target right channel signal can be improved.

Wherein the signal equalization processing includes power equalization processing and/or frequency response equalization processing. As an example, the signal equalization processing includes power equalization processing, and the performing signal equalization processing on the third left channel signal and the third right channel signal in step S22 to obtain a target left channel signal and a target right channel signal includes:

step A31, calculating the same-side filter coefficient and different-side filter coefficient according to the standard opening angle and the loudspeaker opening angle;

a32, calculating the square sum of the ipsilateral side filter coefficient and the ipsilateral side filter coefficient to obtain a first target value;

a33, calculating the square value of the first target value to obtain a second target value;

step A34, determining the reciprocal of the second target value to obtain a power balance coefficient;

and step A35, respectively carrying out signal modulation on the third left channel signal and the third right channel signal according to the power balance coefficient to obtain a target left channel signal and a target right channel signal.

The same-side filter coefficient and the different-side filter coefficient can be calculated according to a first head related transfer function and a second head related transfer function corresponding to the opening angle of the loudspeaker, and a third head related transfer function and a fourth head related transfer function corresponding to the standard opening angle. The specific calculation process may refer to the processing process shown in the foregoing formula (6), and the embodiment of the present invention will not be further described herein.

Recording the same side filter coefficient as G _L (θ _L F) the different side filter coefficient is G _L (θ _R F), the first target value may be expressed as:

M ₁ ＝G _L (θ _L ,f) ² +G _L (θ _R ,f) ² (10)

the second target value may be expressed as:

the power equalization coefficients may be expressed as:

according to the power equalization coefficient EQ _P And carrying out signal modulation on the third left channel signal and the third right channel signal to obtain a target left channel signal and a target right channel signal.

Specifically, the third left channel signal L is combined with the foregoing equation (8) and equation (9) ₃ And the third right channel signal R ₃ Expressed as:

L ₃ ＝G _L (θ _L ,f)L+G _L (θ _R ,f)R (13)

R ₃ ＝G _L (θ _R ,f)L+G _L (θ _L ,f)R (14)

then, the target left channel signal L 'and the target right channel signal R' can be expressed as:

in the embodiment of the invention, the third left channel signal and the third right channel signal after stereo widening are subjected to power equalization, so that tone distortion in the target left channel signal and the target right channel signal can be effectively reduced, and the tone quality is improved.

In the embodiment of the present invention, two stereo widening processing procedures are shown, namely, the processing procedures shown in step a11 to step a13 and the processing procedures shown in step a21 to step a 24. The power equalization processing procedure shown in the above steps a31 to a35 is applicable to any stereo widening processing procedure.

The power equalization processing procedure described in the above steps a31 to a35 is only an exemplary illustration of the present invention, and is not meant to limit the present invention. In the practical application process, the third left channel signal and the third right channel signal obtained by stereo widening may be subjected to power equalization in any manner, so long as tone distortion of the target left channel signal and the target right channel signal can be reduced.

In the embodiment of the invention, besides performing power equalization processing on the third left channel signal and the third right channel signal, the tone color distortion of the generated target left channel signal and target right channel signal is avoided, and the tone color fidelity and the contrast definition are improved; the third left channel signal and the third right channel signal may also be frequency-response equalized to reduce frequency distortion of the generated target left channel signal and target right channel signal.

As another example, the signal equalization processing includes frequency response equalization processing, and the performing signal equalization processing on the third left channel signal and the third right channel signal in step S22 to obtain a target left channel signal and a target right channel signal includes:

Step A41, respectively performing high-pass filtering processing and low-pass filtering processing on the third left channel signal and the third right channel signal to obtain a left channel high-frequency signal, a right channel high-frequency signal, a left channel middle-low frequency signal and a right channel middle-low frequency signal;

step A42, performing superposition processing on the left channel high-frequency signal and the left channel middle-low frequency signal to obtain a target left channel signal;

and A43, performing superposition processing on the right channel high-frequency signal and the right channel middle-low frequency signal to obtain a target right channel signal.

The audio signal generally includes a bass segment, a mid-audio segment, a mid-high audio segment, a high-audio segment, and the like. The bass frequency band refers to a frequency band of 80Hz-250Hz and comprises basic tones of all sound parts in the audio signal, the balance state of the audio signal can be changed by adjusting the bass frequency band, so that the audio signal tends to be plump or thin, the 'rumble' sound can be caused if the bass frequency band is lifted excessively, and the listening feeling of the audio signal can be clumsy if the frequency band of 100Hz-160Hz in the audio signal occupies more. The middle audio frequency range refers to a frequency range of 250Hz-2000Hz, and the tone strength of the audio signal can be changed by adjusting the middle audio frequency range, but tone similar to iron sheet sound can be generated when the tone strength is excessively improved, and the hearing is affected. The middle-high frequency band refers to a frequency band of 2000Hz-4000Hz, the tone color of the frequency band is relatively sharp, the layering sense of middle and high frequencies is damaged, the recognition of voice can be masked by the excessive lifting of the middle-high frequency band, and adverse reactions such as fatigue and vexation of listeners are easily caused. The high-frequency band refers to a frequency band of 4000Hz-6000Hz, the frequency band can bring a feeling of being in the scene to a listener, the definition of language and music can be increased, the elevation of the high-frequency band can change the sound field positioning of the listener to the audio signal, and the feeling of being in the scene to the listener is brought.

Therefore, in the embodiment of the invention, the frequency distortion caused by stereo widening processing can be avoided by carrying out frequency equalization on the third left channel signal and the third right channel signal and moderately changing the duty ratio of each frequency band in the third left channel signal and the third right channel signal, the tone quality of the generated target left channel signal and the tone quality of the target right channel signal are further improved, and the hearing feeling is optimized.

Specifically, the third left channel signal and the third right channel signal can be respectively subjected to filtering processing through a high-pass filter and a low-pass filter, so that high-low frequency noise is filtered, the frequency response curves of the third left channel signal and the third right channel signal tend to be straight, and the purpose of avoiding frequency distortion is achieved.

And when the frequency equalization processing is performed on the third left channel signal and the third right channel signal after the stereo widening processing, subjective and objective analysis can be performed on the audio characteristics of the third left channel signal and the third right channel signal to determine frequency equalization parameters.

In the embodiment of the present invention, the third left channel signal and the third right channel signal obtained by the stereo widening process may be subjected to power equalization process or frequency response equalization process, or the third left channel signal and the third right channel signal may be subjected to power equalization process and frequency response equalization process at the same time. The embodiment of the invention does not specifically limit the sequence of the power equalization processing and the frequency response equalization processing, and can perform the power equalization processing on the third left channel signal and the third right channel signal at the same time and then perform the frequency response equalization processing; the third left channel signal and the third right channel signal may be subjected to frequency response equalization processing at the same time, and then subjected to power equalization processing. For specific processing procedures, reference may be made to the foregoing processing steps of the power equalization processing and the frequency response equalization processing for the third left channel signal and the third right channel signal, and further details of the embodiments of the present invention are not described herein.

In the embodiment of the invention, the multi-channel surround sound signal can comprise a left channel signal and a right channel signal and also can comprise the surround sound channel signal. In other words, the left side signal may include a left pass signal and a left surround pass signal, and the right side signal may include a right pass signal and a right surround pass signal. For example, a relatively wide range of surround sound signals are currently in use: the 5.1 channel audio signal comprises a center channel signal, a left channel signal, a right channel signal, a low frequency effects channel signal, a left surround effects channel signal, and a right surround effects channel signal.

In an alternative embodiment of the present invention, the left signal includes a left channel signal and a left surround channel signal, the right signal includes a right channel signal and a right surround channel signal, and the determining, in step 101, a standard opening angle corresponding to the multi-channel surround signal to be processed includes:

step S31, determining a first standard opening angle corresponding to a single-channel signal of the multi-channel surround sound signal, and a second standard opening angle corresponding to a surround channel signal of the multi-channel surround sound signal, wherein the single-channel signal comprises a left channel signal and a right channel signal, and the surround channel signal comprises a left surround channel signal and a right surround channel signal;

Step 102 of performing downmix enhancement processing on the left signal and the right signal based on the standard opening angle and the speaker opening angle to obtain a target left channel signal and a target right channel signal, including:

step S32, based on the first standard opening angle and the loudspeaker opening angle, carrying out down-mixing enhancement processing on the left channel signal and the right channel signal to obtain a first left channel signal and a first right channel signal;

step S33, performing down-mixing enhancement processing on the left surrounding channel signal and the right surrounding channel signal based on the second standard opening angle and the loudspeaker opening angle to obtain a second left channel signal and a second right channel signal;

step S34, performing superposition processing on the first left channel signal and the second left channel signal to obtain a target left channel signal;

and step S35, performing superposition processing on the first right channel signal and the second right channel signal to obtain a target right channel signal.

Therefore, when the left signal includes a left channel signal and a left surround channel signal, and the right signal includes a right channel signal and a right surround channel signal, there are two standard opening angles, namely, a first standard opening angle corresponding to the left channel signal and the right channel signal, and a second standard opening angle corresponding to the left surround channel signal and the right surround channel signal. Taking 5.1-channel surround sound as an example, the first standard opening angle is an included angle between a left front speaker for outputting a left-channel signal, a right front speaker for outputting a right-channel signal, and a listener; the second standard opening angle is an included angle between a left rear speaker for outputting a left surround channel signal, a right rear speaker for outputting a right surround channel signal, and a listener.

In the embodiment of the present invention, the processing procedure of performing the downmix enhancement processing on the left surround channel signal and the right surround channel signal is similar to the downmix enhancement processing procedure of the left channel signal and the right surround channel signal, and only the standard opening angle is replaced with the second standard opening angle corresponding to the left surround channel signal and the right surround channel signal. In other words, in the case where the left signal is a left channel signal and the right signal is a right channel signal, all the steps related to the downmix enhancement processing listed above are applicable to the left surround channel signal and the right surround channel signal. The specific processing procedure is described with reference to the foregoing description, and further description of the embodiment of the present invention is omitted herein.

In addition, in the embodiment of the present invention, when the target left channel signal and the target right channel signal of the stereo signal are generated based on the multi-channel surround sound signal, the left side signal and the right side signal of the multi-channel surround sound may be processed, and the center channel signal and the bass channel signal of the multi-channel surround sound may be processed.

Specifically, in an alternative embodiment of the present invention, the multi-channel surround sound signal in step 103 further includes a center channel signal and a bass channel signal, and the outputting, by the speaker of the playback device, the target left channel signal and the target right channel signal respectively includes:

step S41, respectively carrying out attenuation treatment on the mid-set channel signal and the bass channel signal to obtain an attenuated mid-set channel signal and an attenuated bass channel signal;

step S42, superposing the attenuated middle-set channel signal and the attenuated bass channel signal with the target left channel signal and the target right channel signal respectively to obtain a mixed left channel signal and a mixed right channel signal;

step S43, the mixed left channel signal and the mixed right channel signal are respectively output through the loudspeaker of the external device.

Referring to fig. 3, a process flow diagram of an audio signal is shown in accordance with an embodiment of the present invention. As shown in fig. 3, the multi-path surround sound signal includes a left path signal L, a right path signal R, a left surround path signal LS, a right surround path signal RS, a center path signal C, and a bass path signal LFE. Next, a specific processing procedure of each channel signal of the multi-channel surround sound signal according to the embodiment of the present invention will be described with reference to fig. 3.

The left and right channel signals L and R, and the left and right surround channel signals LS and RS, respectively, are subjected to a downmix enhancement process. The downmix enhancement processing includes stereo widening processing and signal equalization processing, and the signal equalization processing may further include power equalization processing and frequency response equalization processing. Before the downmix enhancement processing, first, a first standard opening angle corresponding to the left channel signal L and the right channel signal R is determined through pattern matching, and a second standard opening angle corresponding to the left surround channel signal LS and the right surround channel signal RS is determined, and then the downmix enhancement is performed based on the respective standard opening angles. For specific processing procedures, reference may be made to the downmix enhancement processing procedure of the left side signal and the right side signal in the foregoing respective embodiments, and embodiments of the present invention are not limited herein in detail.

The first left channel signal L is obtained by performing down-mixing enhancement processing on the left channel signal L, the right channel signal R, the left surround channel signal LS and the right surround channel signal RS ₁ First right channel signal R ₁ First, theTwo left channel signal LS ₂ And a second right channel signal RS ₂ 。

Then, for the first left channel signal L ₁ And a second left channel signal LS ₂ And performing superposition processing to obtain a target left channel signal L 'and a target right channel signal R'.

For the center channel signal C and the bass channel signal LFE, attenuation processing may be performed, and the attenuated center channel signal and the attenuated bass channel signal may be respectively superimposed with the target left channel signal L 'and the target right channel signal R', to obtain a mixed left channel signal l″ and a mixed right channel signal R ".

Finally, the mixed left channel signal l″ and the mixed right channel signal r″ are output through the left and right speakers of the playback device, respectively.

In the embodiment of the invention, the finally output mixed left channel signal L 'and mixed right channel signal R' contain the relevant components of each channel signal in the multichannel surround sound signal, so that the spatial information of the multichannel surround sound signal can be reserved to the maximum extent, the spatial sense of the audio signal output by the playing equipment is increased, and the surround sound effect is improved.

In an optional embodiment of the present invention, the attenuating processing performed on the mid-channel signal and the bass channel signal in step S41 to obtain an attenuated mid-channel signal and an attenuated bass channel signal includes:

sub-step S411, adjusting a signal energy gain of the mid-channel signal and/or the bass channel signal according to an audio content of the multi-channel surround sound signal;

sub-step S412, performing attenuation processing on the mid-channel signal and the bass channel signal after signal energy gain adjustment, to obtain an attenuated mid-channel signal and an attenuated bass channel signal, respectively.

Wherein the signal energy gain of each channel signal is used to characterize the signal strength, the greater the signal energy gain, the greater the signal strength of the channel signal. The signal energy gain of each channel signal may be different for different types of audio content target audio signals. For example, in audio signals of various kinds of programs and video programs, the number of people is large, so in order to ensure the definition of the audio signals finally output, the signal energy gain of the middle-set channel signal can be increased appropriately; in the audio signal of the music program, the task is less, so the signal energy gain of the center channel signal can be properly reduced, and the like.

In some commonly used head related transfer function libraries, low frequency attenuation exists, and part of head related transfer functions have certain loss in the low frequency part. If there is a low frequency loss in the head related transfer function used, this results in loss of part of the low frequency signal of the multi-channel surround sound signal in the generated target left channel signal and target right channel signal. Accordingly, the target left channel signal and the target right channel signal can be bass-compensated by appropriately increasing the signal energy gain of the bass channel signal.

The embodiment of the invention can properly adjust the middle channel signal of the multichannel surround sound signal and/or the signal energy gain of the bass channel signal according to the actual requirement, can meet the presentation requirement of various surround sound effects, obtain personalized sound effects and improve the applicability of the audio signal generation method.

In summary, the embodiment of the invention performs the downmix enhancement processing on the left signal in the multichannel surround sound signal based on the multichannel surround sound signal and the speaker opening angle of the external device, so that the virtual opening angle is consistent with the standard opening angle of the multichannel surround sound signal after the processed target left channel signal and the processed target right channel signal are output by the external device, thereby breaking through the limitation of the speaker opening angle of the external device on the sound field, widening the sound field of the audio signal output by the external device, enabling the processed audio signal to present an omnibearing surround sound field through the external device, increasing the spatial sense of the audio signal output by the external device, and improving the surround sound effect.

Fig. 4 is a block diagram of an audio signal processing apparatus according to an embodiment of the present invention, where the apparatus is applied to a playback device, and the playback device includes at least two speakers, and as shown in fig. 4, the apparatus 40 may include:

the opening angle determining module 401 is configured to determine a standard opening angle corresponding to a multichannel surround signal to be processed, and a speaker opening angle of the playback device, where the multichannel surround signal includes a left signal and a right signal;

a downmix enhancement processing module 402, configured to perform a downmix enhancement processing on the left signal and the right signal based on the standard opening angle and the speaker opening angle, to obtain a target left channel signal and a target right channel signal;

and a signal output module 403, configured to output the target left channel signal and the target right channel signal through a speaker of the playback device, respectively.

In an alternative embodiment of the present invention, the downmix enhancement processing includes stereo widening processing, and the downmix enhancement processing module includes:

a first binaural sound pressure calculation sub-module, configured to calculate a first binaural sound pressure corresponding to the multi-path surround sound signal according to the standard opening angle;

A first stereo widening processing sub-module, configured to perform stereo widening processing on the left signal and the right signal based on the speaker opening angle and the first binaural sound pressure, to obtain a target left channel signal and a target right channel signal; and the second binaural sound pressure generated by the target left channel signal and the target right channel signal is the same as the first binaural sound pressure.

In an alternative embodiment of the invention, the first stereo widening processing sub-module includes:

a first head related transfer function determining unit, configured to determine a first head related transfer function and a second head related transfer function corresponding to the opening angle of the speaker, where the first head related transfer function is a same-side ear head related transfer function, and the second head related transfer function is a different-side ear head related transfer function;

a matrix determining unit configured to determine an inverse matrix of a symmetric matrix of the first head related transfer function and the second head related transfer function;

and the time domain convolution processing unit is used for performing time domain convolution processing on the inverse matrix and the first binaural sound pressure to obtain a target left channel signal and a target right channel signal, so that second binaural sound pressure generated by the target left channel signal and the target right channel signal is the same as the first binaural sound pressure corresponding to the multichannel surround sound signal.

In an alternative embodiment of the present invention, the first stereo widening processing sub-module includes:

a second head related transfer function determining unit, configured to determine a first head related transfer function and a second head related transfer function corresponding to the opening angle of the speaker, where the first head related transfer function is a same-side ear head related transfer function, and the second head related transfer function is a different-side ear head related transfer function;

a third head related transfer function determining unit, configured to determine a third head related transfer function and a fourth head related transfer function corresponding to the standard opening angle, where the third head related transfer function is a ipsilateral ear head related transfer function, and the fourth head related transfer function is a ipsilateral ear head related transfer function;

a target filter coefficient calculating unit, configured to calculate a target filter coefficient according to the first head related transfer function, the second head related transfer function, the third head related transfer function, and the fourth head related transfer function, where the target filter coefficient is used to determine information to be stretched corresponding to the left signal and the right signal;

the first filtering processing unit is used for carrying out filtering processing on the left side signal and the right side signal based on the target filtering coefficient to obtain a target left channel signal and a target right channel signal, and second binaural sound pressure generated by the target left channel signal and the target right channel signal is the same as first binaural sound pressure corresponding to the multichannel surround sound signal; the target filter coefficient is a symmetric matrix formed by the same-side filter coefficient and different-side filter coefficient.

In an alternative embodiment of the present invention, the target filter coefficient calculating unit includes:

a first matrix determining subunit, configured to determine an inverse matrix of a first symmetric matrix corresponding to the first head related transfer function and the second head related transfer function;

a second matrix determining subunit, configured to determine a second symmetric matrix corresponding to the third head related transfer function and the fourth head related transfer function;

and the matrix operation subunit is used for calculating the product of the inverse matrix of the first symmetric matrix and the second symmetric matrix to obtain a target filter coefficient.

In an alternative embodiment of the present invention, the filtering processing unit includes:

the first filtering processing subunit is used for respectively carrying out filtering processing on the left side signals based on the same side filtering coefficient and the different side filtering coefficient to obtain a first left side signal and a second left side signal, wherein the first left side signal corresponds to the same side filtering coefficient, and the second left side signal corresponds to the different side filtering coefficient;

the second filtering processing subunit is used for respectively carrying out filtering processing on the right-side signal based on the same-side filtering coefficient and the different-side filtering coefficient to obtain a first right-side signal and a second right-side signal, wherein the first right-side signal corresponds to the same-side filtering coefficient, and the second right-side signal corresponds to the different-side filtering coefficient;

A first signal superposition subunit, configured to perform superposition processing on the first left signal and the second right signal, to obtain a target left channel signal;

and the second signal superposition subunit is used for superposing the second left-side signal and the first right-side signal to obtain a target right channel signal.

In an alternative embodiment of the present invention, the downmix enhancement processing includes a stereo widening processing and a signal equalizing processing, and the downmix enhancement processing module includes:

the second stereo widening processing submodule is used for carrying out stereo widening processing on the left side signal and the right side signal based on the standard opening angle and the loudspeaker opening angle to obtain a widened third left channel signal and a widened third right channel signal;

and the first signal equalization processing submodule is used for carrying out signal equalization processing on the third left channel signal and the third right channel signal to obtain a target left channel signal and a target right channel signal, and the signal equalization processing comprises power equalization processing and/or frequency response equalization processing.

In an alternative embodiment of the present invention, the signal equalization processing includes power equalization processing, and the first signal equalization processing sub-module includes:

The first equalization coefficient calculation unit is used for calculating the ipsilateral filter coefficient and the heterolateral filter coefficient according to the standard opening angle and the loudspeaker opening angle;

a first target value calculation unit, configured to calculate a sum of squares of the ipsilateral filter coefficient and the ipsilateral filter coefficient, to obtain a first target value;

a second target value calculation unit, configured to calculate a square value of the first target value, to obtain a second target value;

a second equalization coefficient calculation unit, configured to determine an inverse of the second target value, to obtain a power equalization coefficient;

and the signal modulation unit is used for respectively carrying out signal modulation on the third left channel signal and the third right channel signal according to the power balance coefficient to obtain a target left channel signal and a target right channel signal.

In an alternative embodiment of the present invention, the signal equalization processing includes frequency response equalization processing, and the first signal equalization processing sub-module includes:

the second filtering processing unit is used for respectively carrying out high-pass filtering processing and low-pass filtering processing on the third left channel signal and the third right channel signal to obtain a left channel high-frequency signal, a right channel high-frequency signal, a left channel middle-low frequency signal and a right channel middle-low frequency signal;

The first superposition processing unit is used for carrying out superposition processing on the left channel high-frequency signal and the left channel middle-low frequency signal to obtain a target left channel signal;

and the second superposition processing unit is used for carrying out superposition processing on the right channel high-frequency signal and the right channel middle-low frequency signal to obtain a target right channel signal.

In an alternative embodiment of the present invention, the left side signal comprises a left pass signal and a left surround pass signal, the right side signal comprises a right pass signal and a right surround pass signal,

the opening angle determining module comprises:

the opening angle determining submodule is used for determining a first standard opening angle corresponding to a single-channel signal of the multi-channel surround sound signal and a second standard opening angle corresponding to a surround channel signal of the multi-channel surround sound signal, wherein the single-channel signal comprises a left channel signal and a right channel signal, and the surround channel signal comprises a left surround channel signal and a right surround channel signal;

the downmix enhancement processing module includes:

the first downmix enhancement processing submodule is used for carrying out downmix enhancement processing on the left channel signal and the right channel signal based on the first standard opening angle and the loudspeaker opening angle to obtain a first left channel signal and a first right channel signal;

The second downmix enhancement processing sub-module is configured to perform a downmix enhancement processing on the left surround channel signal and the right surround channel signal based on the second standard opening angle and the speaker opening angle, to obtain a second left channel signal and a second right channel signal;

the first superposition processing submodule is used for carrying out superposition processing on the first left channel signal and the second left channel signal to obtain a target left channel signal;

and the second superposition processing submodule is used for carrying out superposition processing on the first right channel signal and the second right channel signal to obtain a target right channel signal.

In an alternative embodiment of the present invention, the multi-path surround sound signal further includes a center path signal and a bass path signal, and the signal output module includes:

the attenuation processing submodule is used for respectively carrying out attenuation processing on the mid-set channel signal and the bass channel signal to obtain an attenuated mid-set channel signal and an attenuated bass channel signal;

a third superposition processing sub-module, configured to superimpose the attenuated mid-channel signal and the attenuated bass channel signal with the target left channel signal and the target right channel signal, respectively, to obtain a mixed left channel signal and a mixed right channel signal;

And the signal output sub-module is used for respectively outputting the mixed left channel signal and the mixed right channel signal through a loudspeaker of the playing device.

In an alternative embodiment of the present invention, the attenuation processing submodule includes:

a signal energy gain adjustment unit, configured to adjust a signal energy gain of the mid-channel signal and/or the bass channel signal according to an audio content of the multichannel surround sound signal;

and the attenuation processing unit is used for respectively carrying out attenuation processing on the mid-set channel signal and the bass channel signal after the signal energy gain adjustment to obtain an attenuated mid-set channel signal and an attenuated bass channel signal.

In summary, according to the audio signal processing apparatus provided by the embodiment of the present invention, the downmix enhancement processing may be performed on the left signal in the multichannel surround sound signal based on the multichannel surround sound signal and the speaker opening angle of the external device, so that after the processed target left channel signal and the processed target right channel signal are output by the external device, the virtual opening angle is consistent with the standard opening angle of the multichannel surround sound signal, thereby breaking through the limitation of the speaker opening angle of the external device on the sound field, widening the sound field of the audio signal output by the external device, and enabling the processed audio signal to exhibit an omnidirectional spatial sense through the external device, and improving the surround sound effect.

For the above-described device embodiments, the description is relatively simple, as it is substantially similar to the method embodiments, with reference to the description of the method embodiments in part.

In addition, the embodiment of the invention also provides a terminal, which comprises a processor, a memory and a computer program stored in the memory and capable of running on the processor, wherein the computer program realizes the processes of the embodiment of the audio signal processing method when being executed by the processor, and can achieve the same technical effects, and the repetition is avoided, so that the description is omitted.

The embodiment of the invention also provides a computer readable storage medium, on which a computer program is stored, which when executed by a processor, implements the processes of the above-mentioned embodiments of the audio signal processing method, and can achieve the same technical effects, so that repetition is avoided, and no further description is given here. Wherein the computer readable storage medium is selected from Read-Only Memory (ROM), random access Memory (Random Access Memory, RAM), magnetic disk or optical disk.

In this specification, each embodiment is described in a progressive manner, and each embodiment is mainly described by differences from other embodiments, and identical and similar parts between the embodiments are all enough to be referred to each other.

As will be readily appreciated by those skilled in the art: any combination of the above embodiments is possible, and thus is an embodiment of the present invention, but the present specification is not limited by the text.

The audio signal processing methods provided herein are not inherently related to any particular computer, virtual system, or other apparatus. Various general-purpose systems may also be used with the teachings herein. The required structure for a system constructed with aspects of the present invention will be apparent from the description above. In addition, the present invention is not directed to any particular programming language. It will be appreciated that the teachings of the present invention described herein may be implemented in a variety of programming languages, and the above description of specific languages is provided for disclosure of enablement and best mode of the present invention.

In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

Similarly, it should be appreciated that in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. However, the disclosed method should not be construed as reflecting the intention that: i.e., the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

Those skilled in the art will appreciate that the modules in the apparatus of the embodiments may be adaptively changed and disposed in one or more apparatuses different from the embodiments. The modules or units or components of the embodiments may be combined into one module or unit or component and, furthermore, they may be divided into a plurality of sub-modules or sub-units or sub-components. Any combination of all features disclosed in this specification (including any accompanying claims, abstract and drawings), and all of the processes or units of any method or apparatus so disclosed, may be used in combination, except insofar as at least some of such features and/or processes or units are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise.

Furthermore, those skilled in the art will appreciate that while some embodiments described herein include some features but not others included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the claims, any of the claimed embodiments may be used in any combination.

Various component embodiments of the invention may be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. Those skilled in the art will appreciate that some or all of the functions of some or all of the components of an operation performing method according to an embodiment of the present invention may be implemented in practice using a microprocessor or Digital Signal Processor (DSP). The present invention can also be implemented as an apparatus or device program (e.g., a computer program and a computer program product) for performing a portion or all of the methods described herein. Such a program embodying the present invention may be stored on a computer readable medium, or may have the form of one or more signals. Such signals may be downloaded from an internet website, provided on a carrier signal, or provided in any other form.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The use of the words first, second, third, etc. do not denote any order. These words may be interpreted as names.

Claims

1. An audio signal processing method, characterized by being applied to an external playback device including at least two speakers, the method comprising:

outputting the target left channel signal and the target right channel signal through a speaker of the playback device, respectively;

the multi-channel surround sound signal further includes a center channel signal and a bass channel signal, and the target left channel signal and the target right channel signal are respectively output through a speaker of the playback device, including:

respectively carrying out attenuation treatment on the mid-set channel signal and the bass channel signal to obtain an attenuated mid-set channel signal and an attenuated bass channel signal;

superposing the attenuated middle-set channel signal and the attenuated bass channel signal with the target left channel signal and the target right channel signal respectively to obtain a mixed left channel signal and a mixed right channel signal;

and respectively outputting the mixed left channel signal and the mixed right channel signal through a loudspeaker of the outer playing device.

2. The method of claim 1, wherein the downmix enhancement process comprises a stereo widening process, and wherein the performing the downmix enhancement process on the left side signal and the right side signal based on the standard opening angle and the speaker opening angle to obtain a target left channel signal and a target right channel signal comprises:

Calculating a first binaural sound pressure corresponding to the multichannel surround sound signal according to the standard opening angle;

based on the opening angle of the loudspeaker and the first binaural sound pressure, carrying out stereo widening processing on the left side signal and the right side signal to obtain a target left channel signal and a target right channel signal; and the second binaural sound pressure generated by the target left channel signal and the target right channel signal is the same as the first binaural sound pressure.

3. The method according to claim 2, wherein said stereo widening the left side signal and the right side signal based on the speaker opening angle and the first binaural sound pressure to obtain a target left channel signal and a target right channel signal, comprises:

determining a first head related transfer function and a second head related transfer function corresponding to the opening angle of the loudspeaker, wherein the first head related transfer function is a same-side ear head related transfer function, and the second head related transfer function is a different-side ear head related transfer function;

determining an inverse of a symmetric matrix of the first head related transfer function and the second head related transfer function;

and performing time domain convolution processing on the inverse matrix and the first binaural sound pressure to obtain a target left channel signal and a target right channel signal, so that second binaural sound pressure generated by the target left channel signal and the target right channel signal is identical to the first binaural sound pressure corresponding to the multichannel surround sound signal.

4. The method according to claim 2, wherein said stereo widening the left side signal and the right side signal based on the speaker opening angle and the first binaural sound pressure to obtain a target left channel signal and a target right channel signal, comprises:

determining a third head related transfer function and a fourth head related transfer function corresponding to the standard opening angle, wherein the third head related transfer function is a same-side ear head related transfer function, and the fourth head related transfer function is a different-side ear head related transfer function;

calculating a target filter coefficient according to the first head related transfer function, the second head related transfer function, the third head related transfer function and the fourth head related transfer function, wherein the target filter coefficient is used for determining information to be stretched corresponding to the left side signal and the right side signal;

filtering the left side signal and the right side signal based on the target filter coefficient to obtain a target left channel signal and a target right channel signal, wherein the second binaural sound pressure generated by the target left channel signal and the target right channel signal is the same as the first binaural sound pressure corresponding to the multichannel surround sound signal; the target filter coefficient is a symmetric matrix formed by the same-side filter coefficient and different-side filter coefficient.

5. The method of claim 4, wherein said calculating target filter coefficients from said first head related transfer function, said second head related transfer function, said third head related transfer function, and said fourth head related transfer function comprises:

determining an inverse matrix of a first symmetric matrix corresponding to the first head related transfer function and the second head related transfer function;

determining a second symmetric matrix corresponding to the third head related transfer function and the fourth head related transfer function;

and calculating the product of the inverse matrix of the first symmetric matrix and the second symmetric matrix to obtain a target filter coefficient.

6. The method of claim 4, wherein filtering the left signal and the right signal based on the target filter coefficients to obtain a target left channel signal and a target right channel signal comprises:

filtering the left signal based on the same-side filter coefficient and different-side filter coefficient respectively to obtain a first left signal and a second left signal, wherein the first left signal corresponds to the same-side filter coefficient, and the second left signal corresponds to the different-side filter coefficient;

The right side signal is subjected to filtering processing based on the same-side filtering coefficient and the different-side filtering coefficient respectively to obtain a first right side signal and a second right side signal, wherein the first right side signal corresponds to the same-side filtering coefficient, and the second right side signal corresponds to the different-side filtering coefficient;

performing superposition processing on the first left side signal and the second right side signal to obtain a target left channel signal;

and performing superposition processing on the second left side signal and the first right side signal to obtain a target right channel signal.

7. The method according to claim 1, wherein the downmix enhancement processing includes a stereo widening processing and a signal equalization processing, and the performing the downmix enhancement processing on the left side signal and the right side signal based on the standard opening angle and the speaker opening angle to obtain a target left channel signal and a target right channel signal includes:

carrying out stereo widening processing on the left side signal and the right side signal based on the standard opening angle and the loudspeaker opening angle to obtain a widened third left channel signal and a widened third right channel signal;

and carrying out signal equalization processing on the third left channel signal and the third right channel signal to obtain a target left channel signal and a target right channel signal, wherein the signal equalization processing comprises power equalization processing and/or frequency response equalization processing.

8. The method of claim 7, wherein the signal equalization processing includes power equalization processing, and wherein the performing signal equalization processing on the third left channel signal and the third right channel signal to obtain a target left channel signal and a target right channel signal includes:

calculating the same-side filter coefficient and different-side filter coefficient according to the standard opening angle and the loudspeaker opening angle;

calculating the square sum of the same-side filter coefficient and the different-side filter coefficient to obtain a first target value;

calculating the square value of the first target value to obtain a second target value;

determining the reciprocal of the second target value to obtain a power balance coefficient;

and respectively carrying out signal modulation on the third left channel signal and the third right channel signal according to the power balance coefficient to obtain a target left channel signal and a target right channel signal.

9. The method of claim 7, wherein the signal equalization processing includes frequency response equalization processing, and wherein the performing signal equalization processing on the third left channel signal and the third right channel signal to obtain a target left channel signal and a target right channel signal includes:

Respectively performing high-pass filtering processing and low-pass filtering processing on the third left channel signal and the third right channel signal to obtain a left channel high-frequency signal, a right channel high-frequency signal, a left channel middle-low frequency signal and a right channel middle-low frequency signal;

superposing the left channel high-frequency signal and the left channel middle-low frequency signal to obtain a target left channel signal;

and superposing the right channel high-frequency signal and the right channel middle-low frequency signal to obtain a target right channel signal.

10. The method of claim 1, wherein the left side signal comprises a left pass signal and a left surround pass signal, the right side signal comprises a right pass signal and a right surround pass signal,

the determining the standard opening angle corresponding to the multi-channel surround sound signal to be processed comprises the following steps:

determining a first standard opening angle corresponding to a single-channel signal of the multi-channel surround sound signal and a second standard opening angle corresponding to a surround channel signal of the multi-channel surround sound signal, wherein the single-channel signal comprises a left channel signal and a right channel signal, and the surround channel signal comprises a left surround channel signal and a right surround channel signal;

The step of performing downmix enhancement processing on the left side signal and the right side signal based on the standard opening angle and the speaker opening angle to obtain a target left channel signal and a target right channel signal, includes:

performing downmix enhancement processing on the left channel signal and the right channel signal based on the first standard opening angle and the speaker opening angle to obtain a first left channel signal and a first right channel signal;

performing down-mixing enhancement processing on the left surround channel signal and the right surround channel signal based on the second standard opening angle and the loudspeaker opening angle to obtain a second left channel signal and a second right channel signal;

performing superposition processing on the first left channel signal and the second left channel signal to obtain a target left channel signal;

and superposing the first right channel signal and the second right channel signal to obtain a target right channel signal.

11. The method of claim 1, wherein the attenuating the mid-channel signal and the bass channel signal, respectively, to obtain an attenuated mid-channel signal and an attenuated bass channel signal, comprises:

Adjusting signal energy gains of the mid-channel signal and/or the bass channel signal according to audio content of the multi-channel surround sound signal;

and respectively carrying out attenuation treatment on the mid-set channel signal and the bass channel signal after signal energy gain adjustment to obtain an attenuated mid-set channel signal and an attenuated bass channel signal.

12. An audio signal processing apparatus for application to a playback device, the playback device comprising at least two speakers, the apparatus comprising:

the signal output module is used for respectively outputting the target left channel signal and the target right channel signal through a loudspeaker of the playing device;

the multi-channel surround sound signal further comprises a mid-channel signal and a bass-channel signal, and the signal output module comprises:

13. A computer readable storage medium, characterized in that the computer readable storage medium has stored thereon a computer program which, when executed by a processor, implements the audio signal processing method according to any of claims 1 to 11.

14. An electronic device, comprising: a processor and a memory, the processor being configured to execute a data processing program stored in the memory to implement the audio signal processing method of any one of claims 1 to 11.