Loudspeaker signal processing method, device, computer equipment and storage medium

Abstract

The present invention relates to the field of loudspeakers and discloses a loudspeaker signal processing method, apparatus, computer device, and storage medium. The method comprises: obtaining a MADI signal and a host computer control instruction for processing the MADI signal; processing the MADI signal into a first audio digital signal; processing the host computer control instruction into an audio control instruction; processing the first audio digital signal into a second audio digital signal according to the audio control instruction; and converting the second audio digital signal into a loudspeaker signal. The present invention can improve the loudspeaker signal processing capability of the loudspeaker signal processing apparatus and reduce the complexity of the loudspeaker system.

Description

Technical Field

[0001] The present invention relates to the field of loudspeakers, and in particular to a loudspeaker signal processing method, device, computer equipment and storage medium. Background Art

[0002] The MADI (serial multi-channel audio digital interface) protocol is an audio signal transmission protocol standard promulgated by the American Audio Engineers Society (AES). This protocol allows the simultaneous transmission of up to 64 channels of 24-bit / 48kHz signals, or up to 16 channels of 24-bit / 192kHz high-format audio signals, over a single optical fiber or coaxial cable. The MADI protocol's superior convenience and high-precision synchronization have made MADI-based audio equipment widely used in the professional audio industry, particularly in recording production.

[0003] There are mainly the following types of audio devices with MADI interfaces on the market: 1. Digital mixing consoles, which mainly collect and process various front-end signals, mix them, and then transmit them to other audio devices through output interfaces including MADI; 2. External multi-channel sound cards, which are equivalent to simplified small mixing consoles, but the number of input and output channels is much smaller than that of digital mixing consoles. They are mainly connected to computers via USB interfaces for personal recording purposes; 3. Built-in MADI sound cards, whose main function is to encode the multi-channel signals in the audio workstation software in the computer in MADI format and transmit them to the next-level audio equipment; 4. Audio format converters, whose function is to convert different audio formats to the target format before transmitting them, including MADI format.

[0004] However, these MADI-equipped audio devices are primarily designed for front-end signal processing and transmission, lacking any dedicated back-end speaker signal processing capabilities. Optimizing the performance of multi-channel speakers requires adding a separate matrix and speaker signal processor to these MADI devices, complicating audio processing system construction and requiring a different interface for complete speaker system debugging. Summary of the Invention

[0005] Based on this, it is necessary to provide a speaker signal processing method, device, computer equipment and storage medium to address the above technical problems, so as to improve the processing capability of the speaker signal processing device on the speaker signal and reduce the complexity of the speaker system.

[0006] A loudspeaker signal processing method, comprising:

[0007] Obtaining a MADI signal and a host computer control instruction for processing the MADI signal;

[0008] Processing the MADI signal into a first audio digital signal; processing the host computer control instruction into an audio control instruction;

[0009] processing the first audio digital signal into a second audio digital signal according to the audio control instruction;

[0010] The second audio digital signal is converted into a speaker signal.

[0011] A loudspeaker signal processing device, comprising:

[0012] A data acquisition module, used to acquire MADI signals and host computer control instructions for processing the MADI signals;

[0013] A first audio processing module, configured to process the MADI signal into a first audio digital signal; and process the host computer control instruction into an audio control instruction;

[0014] a second audio processing module, configured to process the first audio digital signal into a second audio digital signal according to the audio control instruction;

[0015] The digital-to-analog conversion module is configured to convert the second audio digital signal into a speaker signal.

[0016] A computer device includes a memory, a processor, and computer-readable instructions stored in the memory and executable on the processor. When the processor executes the computer-readable instructions, the above-mentioned loudspeaker signal processing method is implemented.

[0017] One or more readable storage media storing computer-readable instructions, wherein when the computer-readable instructions are executed by one or more processors, the one or more processors execute the loudspeaker signal processing method as described above.

[0018] The above-mentioned loudspeaker signal processing method, device, computer equipment and storage medium obtain the original audio data and audio processing instructions by acquiring the MADI signal and the host computer control instruction for processing the MADI signal. The MADI signal is processed into a first audio digital signal; the host computer control instruction is processed into an audio control instruction to convert the MADI signal and the host computer control instruction into data that can be processed by a DSP chip. The first audio digital signal is processed into a second audio digital signal according to the audio control instruction to complete the processing of the first audio digital signal and generate a second audio digital signal adapted to the loudspeaker system. The second audio digital signal is converted into a loudspeaker signal to generate a loudspeaker signal that can be directly output to the loudspeaker system through digital-to-analog conversion. The present invention can improve the processing capability of the loudspeaker signal processing device for the loudspeaker signal and reduce the complexity of the loudspeaker system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0020] Figure 1 is a flow chart of a loudspeaker signal processing method according to an embodiment of the present invention;

[0021] Figure 2 This is a schematic diagram of a flow chart of multi-channel audio data processing by a DSP chip in one embodiment of the present invention;

[0022] Figure 3 is a structural diagram of a loudspeaker signal processing device according to an embodiment of the present invention;

[0023] Figure 4 FIG. 1 is a schematic diagram of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0025] In one embodiment, if Figure 1 As shown, a loudspeaker signal processing method is provided, comprising the following steps S10-S40.

[0026] S10: Acquire a MADI signal and a host computer control instruction for processing the MADI signal.

[0027] It is understood that the speaker signal processing method provided in this embodiment can be implemented using a custom speaker signal processing device. The speaker signal processing device is provided with several processing chips, several input interfaces, and several output interfaces. The input interfaces of the device can be connected to a host computer. The host computer can be a computer installed with speaker signal processing software.

[0028] The MADI signal is a serial multi-channel audio signal that can be output by a MADI sound card of a host computer. The host computer control instruction can be a control instruction generated by speaker signal processing software on the host computer.

[0029] In some cases, the MADI signal and host computer control command may be received directly from a host computer. In other cases, the MADI signal may be a conversion signal of an audio transmission signal from the host computer; and the host computer control command may be a conversion signal of a control transmission signal from the host computer.

[0030] S20: Process the MADI signal into a first audio digital signal; and process the host computer control instruction into an audio control instruction.

[0031] Understandably, the MADI signal needs to be processed to extract the word clock of the audio signal and convert it into TDM (time-division multiplexing) format audio to facilitate audio signal processing. Here, a DSP (Digital Signal Processor) chip can be used to process the MADI signal, generating a first audio digital signal containing the word clock and TDM-formatted audio. The host computer control instructions need to be processed to generate audio control instructions that can be executed by the DSP chip.

[0032] S30: Process the first audio digital signal into a second audio digital signal according to the audio control instruction.

[0033] It is understandable that the DSP chip can process the first audio digital signal according to the audio control instruction to generate the second audio digital signal. Through the processing of the audio control instruction, the first audio digital signal output based on the MADI sound card can be processed into a second audio digital signal adapted to the speaker system. Among them, the audio processing functions implemented by the DSP chip include but are not limited to gain, phase, delay, high-pass filtering, low-pass filtering, equalization, compression, and limiting. The audio data of each channel can be processed separately to implement the corresponding audio processing function. In one example, the equalization function includes a system equalization function, which is used to optimize the characteristic use of the speaker system so that the acoustic characteristics of the speaker system are optimized. Here, the speaker system can be a speaker array composed of a plurality of speakers.

[0034] S40: Convert the second audio digital signal into a speaker signal.

[0035] It is understandable that after obtaining the second audio digital signal, it is necessary to perform digital-to-analog conversion on the second audio digital signal to generate a speaker signal. The speaker signal can be output to the speaker system through the output interface, so that the speaker system plays the sound corresponding to the speaker signal.

[0036] In steps S10-S40, a MADI signal and a host computer control instruction for processing the MADI signal are obtained to obtain original audio data and audio processing instructions. The MADI signal is processed into a first audio digital signal; the host computer control instruction is processed into an audio control instruction to convert the MADI signal and the host computer control instruction into data that can be processed by a DSP chip. The first audio digital signal is processed into a second audio digital signal according to the audio control instruction to complete the processing of the first audio digital signal and generate a second audio digital signal that is compatible with the speaker system. The second audio digital signal is converted into a speaker signal to generate a speaker signal that can be directly output to the speaker system through digital-to-analog conversion. This embodiment can improve the processing capability of the speaker signal processing device for the speaker signal and reduce the complexity of the speaker system.

[0037] Optionally, in step S20, that is, processing the MADI signal into a first audio digital signal, includes:

[0038] S201: Process the MADI signal using a first computing chip to generate a first audio digital signal, where the first audio digital signal includes a first audio signal and a first word clock.

[0039] Understandably, the first computing chip is a chip that can convert a MADI signal into TDM-formatted audio (i.e., the first audio signal in the first audio digital signal). In some examples, the first computing chip can be an FPGA (Field Programmable Gate Array) chip. The FPGA chip can recover the first word clock of the audio signal from the MADI signal and transmit the first word clock to the DSP chip. The FPGA chip can also convert the MADI signal into a TDM-formatted digital signal, perform matrix operations on the signal as needed, generate the first audio signal, and then transmit the first audio signal to the DSP chip.

[0040] Optionally, in step S30, that is, processing the first audio digital signal into a second audio digital signal according to the audio control instruction, includes:

[0041] S301: Process the first audio digital signal by using a second computing chip to generate a second audio digital signal, where the second audio digital signal includes a second audio signal and a second word clock.

[0042] It is understandable that the second computing chip is a chip that can convert the first audio digital signal into a second audio signal (adapted to the speaker system). In some examples, the second computing chip can be a DSP chip. The DSP chip is responsible for performing audio processing on the first audio digital signal transmitted by the FPGA chip and generating a corresponding second audio digital signal. Here, the audio processing functions implemented by the DSP chip include but are not limited to gain, phase, delay, high-pass filtering, low-pass filtering, equalization, compression, and limiting. Figure 2 As shown, the DSP chip can process multi-channel audio data through matrix operations. The number of audio channels processed by the DSP chip can be set according to actual needs.

[0043] In one example, based on the MADI protocol, a MADI signal supports up to 64 channels of audio data. In some examples, an FPGA chip can convert the 64-channel MADI signal into a 16-channel first digital audio signal. The DSP chip then processes the 16-channel first digital audio signal to generate a 16-channel second digital audio signal.

[0044] The second audio data includes a second audio signal and a second word clock. Here, the second audio signal is a digital audio signal of the first audio signal adjusted to adapt to the speaker system, and the second word clock is a time signal of the first word clock adjusted to adapt to the speaker system.

[0045] Optionally, step S40, i.e., converting the second audio digital signal into a speaker signal, includes:

[0046] S401: Send the second audio digital signal to a digital-to-analog converter through a second computing chip, so that a phase-locked loop in the digital-to-analog converter multiplies the frequency of a second word clock in the second audio digital signal to generate a bit time;

[0047] S402: Receive the bit time through a second computing chip, and send a second audio signal in the second audio digital signal to the digital-to-analog converter according to the bit time, so that the digital-to-analog converter converts the second audio signal into the speaker signal.

[0048] Understandably, the second computing chip can be a DSP chip. The second computing chip can send the second word clock to a digital-to-analog converter (DAC). A phase-locked loop (PLL) in the DAC multiplies the second word clock to obtain the bit clock required for digital-to-analog conversion, and transmits the bit clock back to the DSP chip. The DSP chip sends the second audio signal to the DAC based on the bit clock. The DAC converts the second audio signal into an analog audio signal, i.e., a speaker signal.

[0049] Optionally, after step S40, that is, after converting the second audio digital signal into a speaker signal, the method further includes:

[0050] S50: Output the speaker signal to a speaker system.

[0051] It is understood that after the speaker signal is generated, the speaker signal can be delivered to a speaker system, and then transmitted to a power amplifier in the speaker system, which drives the speaker to produce sound.

[0052] Optionally, step S10, i.e., obtaining a MADI signal and a host computer control instruction for processing the MADI signal, includes:

[0053] S101, receiving an audio transmission signal and a control transmission signal, wherein the control transmission signal is associated with a system parameter of the speaker system;

[0054] S102: Convert the audio transmission signal into the MADI signal; and convert the control transmission signal into the host computer control instruction.

[0055] Understandably, the input interface can receive audio transmission signals and control transmission signals transmitted by the host computer. In one example, the audio transmission signal can be an optical signal, and the corresponding input interface can be a fiber optic interface. The fiber optic interface can convert the optical signal into an Ethernet signal, which is then demodulated by the Ethernet physical layer receiving chip to generate a MADI signal. In another example, a TCP / IP connection can be established with the host computer via a network communication chip, allowing the host computer to communicate with a microcontroller chip (MCU). The microcontroller chip receives the control transmission signal from the host computer, analyzes it, and generates corresponding host computer control instructions for execution by the DSP chip. System engineers can optimize the various audio processing features of the DSP chip based on the measured characteristics of the speakers in each channel of the speaker to obtain optimal speaker characteristics. In some cases, users can also control the user equalizer within the DSP through the host computer to obtain sound that meets specific requirements. For example, in automobile wind noise research, adjusting the user equalizer to pre-attenuate noise in certain frequency bands can verify the acoustic properties of noise reduction materials.

[0056] Yes, the audio transmission signal is transmitted via an optical fiber or a coaxial cable;

[0057] The control transmission signal is transmitted through a network cable.

[0058] Understandably, the audio transmission signal can be transmitted via optical fiber or coaxial cable, preferably optical fiber. Optical fiber has better signal isolation capabilities, is less likely to interfere with each other between upper and lower level devices, and has a longer transmission distance. The control transmission signal can be transmitted via network cable.

[0059] The speaker signal processing method provided in this embodiment integrates the functions of independent multi-channel MADI sound cards and speaker processors currently available on the market, making the entire speaker system extremely simple, saving the space and engineering effort required for speaker system installation, and making it easier to optimize and debug the speaker system. It also greatly improves the speaker signal processing capabilities of the speaker signal processing device and reduces the complexity of the speaker system.

[0060] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0061] In one embodiment, a loudspeaker signal processing device is provided, which corresponds to the loudspeaker signal processing method in the above embodiment. Figure 3As shown, the speaker signal processing device includes a data acquisition module 10, a first audio processing module 20, a second audio processing module 30 and a digital-to-analog conversion module 40. The functional modules are described in detail as follows:

[0062] A data acquisition module 10 is used to acquire MADI signals and host computer control instructions for processing the MADI signals;

[0063] The first audio processing module 20 is used to process the MADI signal into a first audio digital signal; and process the host computer control instruction into an audio control instruction;

[0064] A second audio processing module 30 is configured to process the first audio digital signal into a second audio digital signal according to the audio control instruction;

[0065] The digital-to-analog conversion module 40 is configured to convert the second audio digital signal into a speaker signal.

[0066] Optionally, the first audio processing module 20 includes:

[0067] The first audio processing unit is configured to process the MADI signal through a first computing chip to generate the first audio digital signal, where the first audio digital signal includes a first audio signal and a first word clock.

[0068] Optionally, the second audio processing module 20 includes:

[0069] The second audio processing unit is configured to process the first audio digital signal through a second computing chip to generate a second audio digital signal, where the second audio digital signal includes a second audio signal and a second word clock.

[0070] Optionally, the digital-to-analog conversion module 40 includes:

[0071] a bit time determination unit, configured to send the second audio digital signal to a digital-to-analog converter via a second computing chip, so that a phase-locked loop in the digital-to-analog converter multiplies the second word clock in the second audio digital signal to generate a bit time;

[0072] The analog-to-digital conversion unit is configured to receive the bit time through a second computing chip, and send the second audio signal in the second audio digital signal to the digital-to-analog converter according to the bit time, so that the digital-to-analog converter converts the second audio signal into the speaker signal.

[0073] Optionally, the loudspeaker signal processing device further includes:

[0074] The signal output module is used to output the speaker signal to the speaker system.

[0075] Optionally, the data acquisition module 10 includes:

[0076] a transmission signal receiving unit, configured to receive an audio transmission signal and a control transmission signal, wherein the control transmission signal is associated with a system parameter of the speaker system;

[0077] The signal conversion unit is used to convert the audio transmission signal into the MADI signal; and convert the control transmission signal into the host computer control instruction.

[0078] Optionally, the audio transmission signal is transmitted via an optical fiber or a coaxial cable;

[0079] The control transmission signal is transmitted through a network cable.

[0080] The specific definition of the loudspeaker signal processing device can be found in the definition of the loudspeaker signal processing method above and will not be repeated here. Each module in the loudspeaker signal processing device described above may be implemented in whole or in part via software, hardware, or a combination thereof. Each module may be embedded in or independent of a processor in a computer device in hardware form, or may be stored in a computer device memory in software form, allowing the processor to call and execute the corresponding operations of each module.

[0081] In one embodiment, a computer device is provided. The computer device may be a terminal, and its internal structure diagram may be as follows: Figure 4 As shown. The computer device includes a processor, a memory, an input interface and an output interface connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a readable storage medium and an internal memory. The non-volatile storage medium stores an operating system and computer-readable instructions. The internal memory provides an environment for the operation of the operating system and computer-readable instructions in the readable storage medium. The input interface of the computer device is used to connect to a host computer, and the output interface is connected to a speaker system. When the computer-readable instructions are executed by the processor, a speaker signal processing method is implemented. The readable storage medium provided in this embodiment includes a non-volatile readable storage medium and a volatile readable storage medium.

[0082] In one embodiment, a computer device is provided, comprising a memory, a processor, and computer-readable instructions stored in the memory and executable on the processor. When the processor executes the computer-readable instructions, the following steps are implemented:

[0083] Obtaining a MADI signal and a host computer control instruction for processing the MADI signal;

[0084] Processing the MADI signal into a first audio digital signal; processing the host computer control instruction into an audio control instruction;

[0085] processing the first audio digital signal into a second audio digital signal according to the audio control instruction;

[0086] The second audio digital signal is converted into a speaker signal.

[0087] In one embodiment, one or more computer-readable storage media storing computer-readable instructions are provided. The computer-readable storage media provided in this embodiment include non-volatile computer-readable storage media and volatile computer-readable storage media. The computer-readable storage media store computer-readable instructions that, when executed by one or more processors, implement the following steps:

[0088] Obtaining a MADI signal and a host computer control instruction for processing the MADI signal;

[0089] Processing the MADI signal into a first audio digital signal; processing the host computer control instruction into an audio control instruction;

[0090] processing the first audio digital signal into a second audio digital signal according to the audio control instruction;

[0091] The second audio digital signal is converted into a speaker signal.

[0092] Those skilled in the art will understand that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing related hardware through computer-readable instructions. The computer-readable instructions can be stored in a non-volatile readable storage medium or a volatile readable storage medium. When the computer-readable instructions are executed, they can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), Synchronous Link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0093] Those skilled in the art will clearly understand that for the sake of convenience and brevity of description, only the division of the above-mentioned functional units and modules is used as an example. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above.

[0094] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the scope of protection of the present invention.

Claims

1. A loudspeaker signal processing method, characterized in that: include: Acquire a serial multi-channel audio digital interface (MADI) signal and a host computer control instruction for processing the MADI signal; Processing the MADI signal into a first audio digital signal; processing the host computer control instruction into an audio control instruction; processing the first audio digital signal into a second audio digital signal according to the audio control instruction; converting the second audio digital signal into a speaker signal; The processing of the MADI signal into a first audio digital signal comprises: recovering the MADI signal using a first computing chip to obtain a first word clock, converting the MADI signal into a digital signal in a TDM format, and performing a matrix operation on the digital signal in the TDM format to obtain a first audio signal, where the first audio digital signal includes the first audio signal and the first word clock; The processing of the first audio digital signal into a second audio digital signal according to the audio control instruction includes: According to the audio control instruction, the first word clock is adjusted by a second computing chip to obtain a second word clock, and the first audio signal is adjusted to obtain a second audio signal. The second audio digital signal includes the second audio signal and the second word clock.

2. The loudspeaker signal processing method according to claim 1, wherein: Converting the second audio digital signal into a speaker signal comprises: sending the second audio digital signal to a digital-to-analog converter via a second computing chip, so that a phase-locked loop in the digital-to-analog converter multiplies the second word clock in the second audio digital signal to generate a bit time; The bit time is received by a second computing chip, and a second audio signal in the second audio digital signal is sent to the digital-to-analog converter according to the bit time, so that the digital-to-analog converter converts the second audio signal into the speaker signal.

3. The loudspeaker signal processing method according to claim 1, wherein: After converting the second audio digital signal into a speaker signal, the method further includes: The speaker signal is output to a speaker system.

4. The loudspeaker signal processing method according to claim 3, wherein: The obtaining of the MADI signal and the host computer control instructions for processing the MADI signal include: receiving an audio transmission signal and a control transmission signal, wherein the control transmission signal is associated with a system parameter of the speaker system; The audio transmission signal is converted into the MADI signal; and the control transmission signal is converted into the host computer control instruction.

5. The loudspeaker signal processing method according to claim 4, wherein: The audio transmission signal is transmitted via an optical fiber or a coaxial cable; The control transmission signal is transmitted through a network cable.

6. A loudspeaker signal processing device, characterized in that: include: A data acquisition module for acquiring a MADI (Multi-channel Audio Digital Interface) signal and a host computer control instruction for processing the MADI signal; A first audio processing module, configured to process the MADI signal into a first audio digital signal; and process the host computer control instruction into an audio control instruction; a second audio processing module, configured to process the first audio digital signal into a second audio digital signal according to the audio control instruction; a digital-to-analog conversion module, configured to convert the second audio digital signal into a speaker signal; The first audio processing module includes: a first audio processing unit, configured to recover the MADI signal using a first computing chip to obtain a first word clock, convert the MADI signal into a digital signal in a TDM format, and perform a matrix operation on the digital signal in the TDM format to obtain a first audio signal, where the first audio digital signal includes the first audio signal and the first word clock; The second audio processing module includes: The second audio processing unit is used to adjust the first word clock through the second computing chip according to the audio control instruction to obtain a second word clock, and adjust the first audio signal to obtain a second audio signal, where the second audio digital signal includes the second audio signal and the second word clock.

7. A computer device comprising a memory, a processor, and computer-readable instructions stored in the memory and executable on the processor, wherein: When the processor executes the computer-readable instructions, the loudspeaker signal processing method according to any one of claims 1 to 5 is implemented. 8 . A readable storage medium storing computer-readable instructions, wherein when the computer-readable instructions are executed by one or more processors, the one or more processors are caused to perform the loudspeaker signal processing method according to claim 1 .

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