Apparatus for processing multichannel audio signals, method for processing multichannel audio signals, and computer-readable storage medium

Abstract

An apparatus for processing a multi-channel audio signal including at least a left channel, a right channel and a centre channel is provided, the apparatus comprising: a centre extraction unit adapted to extract a centre signal from the left channel and the right channel leaving a left residual signal and a right residual signal, a first summing unit adapted to add the extracted centre signal to the centre channel of the multi-channel audio signal to obtain an enhanced centre channel, a second summing unit adapted to add the enhanced centre channel to the right residual signal to obtain an enhanced right channel, a third summing unit adapted to add the enhanced centre channel to the left residual signal to obtain an enhanced left channel, and outputs for providing the enhanced left channel, the enhanced right channel and the enhanced centre channel.

Description

[Technical Field]

[0001] The present invention relates to an apparatus for processing multichannel audio signals. The present invention also relates to a method for processing multichannel audio signals and a computer-readable storage medium.

[0002] Audio signals are typically optimized for playback in a standardized environment. Multi-channel audio signals, in particular, require loudspeakers positioned precisely for a single listener to achieve the intended spatial image. This ideal listener position is known as the sweet spot. However, in some cases, such as in a car, audio playback may be directed towards two listeners. In this case, while the listeners' positions are fixed, they are usually not in the sweet spot. Therefore, it may be desirable to optimize the audio signal for playback in such environments.

[0003] Creating the right spatial image in a car is difficult. In standardized environments such as recording studios, the listener can be positioned in a sweet spot where the distance and angle between the listener and the speakers are predetermined, for example, symmetrical. However, this is usually impossible in a car, which typically has two or more seats in the front. Most cars have left and right speakers, but a simple and effective approach is to add a center speaker to make the imaging more symmetrical. In its simplest form, as shown in Figure 1, a center speaker LS C The signal input to S1 is the sum of the left and right channels L and R. This approach has a significant drawback. Center speaker LS C The outer speaker LS L , LS RBecause it reproduces the same signal, the width of the stereo image is significantly reduced. To improve this, a known solution shown in Figure 2 is to use the center extraction algorithm CEX, which extracts correlation information from the input audio signals L and R. The extracted information CS is the center speaker LS. C and outer speaker LS L , LS R The images are played back on both sides, creating two virtual centers with symmetrical images. In this arrangement, information in the center of the image appears in front of each passenger P1, P2. This has the advantage that correlated information, such as the main vocals of a song, is perceived in front of the passengers. In contrast, uncorrelated information uses the entire width of the available stage.

[0004] The introduction of immersive audio formats into vehicles presents new challenges. The most commonly used immersive audio formats, such as 5.1 surround sound, 7.1 surround sound, Dolby Surround, Dolby Atmos, Auro-3D, and MPEG-H, have three front channels (front left, front center, and front right). Immersive audio formats usually have additional channels, but these will not be considered here. A simple approach is to play the left and right channels with the left and right speakers and use the center channel to create two virtual or phantom centers. This can be achieved by placing two summing blocks S21 and S22, which add the center channel to the left and right channels respectively, as shown in Figure 3. As a result, each virtual center is positioned in front of one of the passengers, and the signal from the center channel is perceived by each passenger from the front.

[0005] However, this approach works in some scenarios but not others. In particular, music can be mixed in a variety of ways. Typically, information that should be perceived in front of the listener, such as the main vocals, is mixed into the center channel. However, in another commonly used mixing style, such information is mixed into the left and right channels. In a studio environment, this works well because it creates a phantom center in the listener's perception. Furthermore, it also has the effect of making instruments blend better with the vocals, so many sound engineers choose this approach in the mixing process. However, in environments where the listener is not in the sweet spot, such as inside a car, in this case, the image of the sound shifts to either the left (driver / passenger on the left) or the right (passenger / driver on the right) rather than directly in the center. Moreover, music is usually not tagged to indicate which mixing style was applied. Therefore, it is difficult to accurately reproduce either style. [Overview of the project]

[0006] Therefore, the object of the present invention is to provide a solution to the above-mentioned problems.

[0007] As described below, the present invention is suitable for solving the problem and creating two phantom centers, one in front of each listening position. Advantageously, this solution works regardless of the mixing style. The input multi-channel audio signal can have conventional formats such as 5.1 surround, 7.1 surround, Dolby Surround, Dolby Atmos, Aurora 3D, MPEG-H, etc.

[0008] In one embodiment, a method for processing a multichannel audio signal including at least a left channel, a right channel, and a center channel includes performing a center extraction on the left and right channels, leaving the left residual signal and the right residual signal, adding the extracted center signal to the center channel to obtain an enhanced center channel, and adding the enhanced center channel to both the left residual signal and the right residual signal. For playback, the left residual signal and the right residual signal, each with the enhanced center channel added, are then supplied to the left and right speakers, and the enhanced center channel is supplied to the center speaker.

[0009] In a further embodiment, the present invention relates to a device for processing a multichannel audio signal including at least a left channel, a right channel, and a center channel. The device comprises a center extraction unit adapted to extract a center signal from the left and right channels, leaving left residual signals and right residual signals. The device further comprises a first adding unit for adding the extracted center signal to the center channel to obtain an enhanced center channel, and two further adding units for adding the enhanced center channel to the left residual signal and right residual signal, respectively. The device supplies the enhanced center channel and the result of adding the left and right residual signals to the enhanced center channel to their respective output units.

[0010] In yet another embodiment, the present invention relates to a computer-readable storage medium that stores instructions, when executed on a computer, causing the computer to perform the method described above. Further advantageous embodiments are disclosed in the detailed description below. [Brief explanation of the drawing]

[0011] Details of the present invention and further advantageous embodiments will be better understood by referring to the accompanying drawings. [Figure 1] The first conventional audio signal processing method. [Figure 2]Second conventional audio signal processing. [Figure 3] A third conventional audio signal processing method. [Figure 4] Block diagram of the audio processing unit. [Figure 5] Audio processing flowchart. [Modes for carrying out the invention]

[0012] Figure 4 shows a block diagram of an audio processing unit 400 according to one embodiment of the present invention. The audio processing unit 400 is a device for processing a multi-channel audio input signal including at least a left channel L, a right channel R, and a center channel C. The device includes a center extraction unit 410 adapted to extract a center signal 410C from the combination of the left channel L and the right channel R of the multi-channel signal. The center extraction unit 410 may correlate with the left channel L and the right channel R and supply the correlated portion 410C to a subsequent processing step. The center extraction unit 410 also supplies the respective remainders 410L and 410R to a subsequent processing step. The device further includes at least three adding units S42 to S44. The first adding unit S42 is adapted to add the extracted center signal 410C to the center channel C of the multi-channel audio input signal to obtain an enhanced center channel 420C. The second adding unit S43 is adapted to add the reinforced center channel 420C to the remainder 410R of the center extraction of the right channel R to obtain the reinforced right channel 430R. The third adding unit S44 is adapted to add the reinforced center channel 420C to the remainder 410L of the center extraction of the left channel L to obtain the reinforced left channel 440L.

[0013] Each of the center extraction unit 410 and the addition units S42, S43, S44 may be implemented by one or more hardware elements such as one or more processors and / or adders, or may be configured by software, but this is not necessary.

[0014] The enhanced left channel 440L, the enhanced right channel 430R, and the enhanced center channel 420C are supplied to the respective output portions of the device. These are, as follows, supplied to respective loudspeakers LS L , LS C , LS R near two listening positions P1, P2. The first speaker LS L is arranged in front of and to the left of the listening positions P1, P2. The second speaker LS R is arranged in front of and to the right of the two listening positions P1, P2. Finally, the third speaker LS C is arranged in front of and at the center of the two listening positions P1, P2. Thus, the listening positions P1, P2 may be two adjacent seats in a vehicle, particularly the driver's seat and the passenger seat. However, the listening positions can also be arranged in other similar environments. Advantageously, this arrangement provides two phantom centers for all audio information to be perceived in front of each listener, one for each listening position.

[0015] The multi-channel audio signal may include analog or digital audio signals. Furthermore, it may also include one or more additional audio channels, which may be supplied to one or more additional speakers, such as to the sides or rear of listening positions P1, P2. These are not considered here. All of the above processing, except for center extraction, may be performed in the analog domain. In particular, the summing unit may perform analog summing or simple superposition of signals. For analog audio input signals, an additional analog-to-digital converter (ADC, not shown) is included to digitize at least the left and right audio channels L and R. If the summing units S42-S44 perform analog summing, an additional digital-to-analog converter (DAC, not shown) is also provided to convert the output signal of the center extraction unit 410 into an analog signal. The ADC and / or DAC may also be part of the center extraction unit 410. Alternatively, the processing may be performed entirely in the digital domain. In this case, the input audio signal may be a digital signal, or the device may have a digitization stage (ADC) to digitize all analog input signals. In the case of digital processing, the device may optionally include a DAC to acquire the analog output signal.

[0016] In one embodiment, the present invention relates to a system having an apparatus for processing the above-described multi-channel audio signal and at least three speakers arranged relative to the above-described two listening positions.

[0017] In one embodiment, the present invention relates to an audio processing method, and particularly to a method for processing a multi-channel audio signal having at least a left channel L, a right channel R, and a center channel C. FIG. 5 shows a flowchart of a method 500 according to an embodiment. Method 500 includes performing center extraction on the left channel L and the right channel R 510 to obtain an extracted center signal 410C, leaving a left residual signal 410L and a right residual signal 410R. The method further includes adding the extracted center signal 410C to the center channel C of the multi-channel audio signal 520 to obtain an enhanced center channel 420C, adding the enhanced center channel 420C to the left residual signal 410L 530 to obtain an enhanced left channel 440L, and adding the enhanced center channel 420C to the right residual signal 410R 540 to obtain an enhanced right channel 430R. The enhanced left channel 440L, the enhanced right channel 430R, and the enhanced center channel 420C can be converted to analog signals as needed and then supplied 550 for output to their respective speakers.

[0018] Specifically, the enhanced left channel 440L can be supplied to a first speaker LS disposed in front of the left of two listening positions P1, P2. L Similarly, the enhanced right channel 430R can be supplied to a second speaker LS disposed in front of the right of two listening positions P1, P2. R Finally, the enhanced center channel 420C can be supplied to a third speaker LS disposed substantially at the center and in front of two listening positions P1, P2. C Optionally, the enhanced channel signals 440L, 430R, 420C can be supplied to additional processing units such as speaker management and delay adjustment before being supplied to their corresponding physical speakers.

[0019] The present invention is particularly advantageous for correctly handling multi-channel audio signals, regardless of how they are mixed, and when neither of the two listeners can be positioned in the conventional sweet spot. That is, sounds that should be perceived in front of the listeners will be perceived in the way intended for each of the two listeners, whether the center information is mixed into the center channel or distributed to the left and right channels. Even intermediate solutions, where some of the center information is mixed into the center channel and some is distributed, can be reproduced as intended. In each case, two phantom centers are created, one for each listener. This means, for example, improved sound reproduction is possible in a car. However, the present invention can also be used in other environments, such as home theaters, trains, and public spaces. It may also be adapted to audio formats with three or more speakers in the front.

[0020] While various embodiments have been described, it is clear that combinations of features from different embodiments are possible, even if not explicitly described herein. Therefore, such combinations are considered to be within the scope of the present invention.

Claims

1. A device for processing multi-channel audio signals, including at least a left channel, a right channel, and a center channel, A center extraction unit adapted to extract the center signal from the left channel and the right channel, leaving the left residual signal and the right residual signal, A first summing unit adapted to obtain an enhanced center channel by adding the extracted center signal to the center channel of the multi-channel audio signal, A second adder unit adapted to acquire the enhanced right channel in addition to the enhanced center channel and the right residual signal, A third adder unit adapted to acquire an enhanced left channel by adding the enhanced center channel to the left residual signal, An apparatus comprising an output unit for supplying the reinforced left channel, the reinforced right channel, and the reinforced center channel, At least the first and second listening positions, The system comprises at least three speakers: a first speaker positioned to the left front of the two listening positions, a second speaker positioned to the right front of the two listening positions, and a third speaker positioned substantially in the center and in front of the two listening positions. The system is configured such that the enhanced left channel is connected to the first speaker, the enhanced right channel to the second speaker, and the enhanced center channel to the third speaker.

2. The aforementioned center extraction unit is a digital processing unit, The system according to claim 1, wherein the first adding unit, the second adding unit, and the third adding unit perform digital addition.

3. The aforementioned center extraction unit is a digital processing unit, The system further comprises a digital-to-analog converter that converts the signal supplied by the center extraction unit into an analog signal, The system according to claim 1, wherein the first adding unit, the second adding unit, and the third adding unit perform analog addition.

4. The aforementioned multi-channel audio signal includes one or more additional audio channels. The system according to claim 1, wherein the one or more additional audio channels are supplied to one or more additional speakers located to the side or behind the listening position.

5. The system according to claim 1, wherein the two listening positions are two adjacent seats in a car.

6. A method for processing a multi-channel audio signal including at least a left channel, a right channel, and a center channel, Center extraction is performed on the left channel and the right channel to obtain the extracted center signal, and the left residual signal and the right residual signal remain. The extracted center signal is added to the center channel of the multi-channel audio signal to acquire an enhanced center channel. The enhanced center channel is added to the left residual signal to acquire the enhanced left channel. The enhanced center channel is added to the right residual signal to acquire the enhanced right channel. This includes supplying the enhanced left channel, the enhanced right channel, and the enhanced center channel to output to each speaker, The aforementioned enhanced left channel is supplied to a first speaker positioned to the left and in front of the two listening positions. The enhanced right channel is supplied to a second speaker located to the right and in front of the two listening positions. The enhanced center channel is supplied to a third speaker positioned substantially centered and in front of the two listening positions.

7. The method according to claim 6, wherein the two listening positions are two adjacent seats in a car.

8. The method according to claim 7, wherein the two adjacent seats are a driver's seat and a passenger seat.

9. A non-temporary computer-readable storage medium that stores instructions that, when executed on a computer, cause the computer to perform the method according to claim 6.

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