TWI868764B - Audio signal processing device and audio signal processing method - Google Patents

Abstract

An audio signal processing device adapted to receive an input audio signal to generate an output audio signal accordingly. The audio signal processing device comprises a controller and a coded. The controller has a storage unit for storing a first parameter set and a second parameter set. The controller receives a selecting signal and selecting one of the first parameter set and the second parameter set as a control parameter set to be output according to the selecting signal. The codec receives the input audio signal and the control parameter set, and converts the input audio signal into the output audio signal according to the control parameter set. Wherein, the first parameter set is characterized with at least one enhanced high-order harmonic for the output audio signal, and the second parameter set is different from the first parameter set.

Description

Audio processing device and audio processing method

The present invention relates to a signal processing device and a processing method, and more particularly to an audio processing device and an audio processing method.

For music lovers, the auditory experience brought by vacuum tube amplifiers and transistor amplifiers is completely different.

Traditionally, if you want to provide the auditory experience of a vacuum tube amplifier, you must use a physical vacuum tube amplifier to achieve it. However, vacuum tubes take up a considerable amount of circuit board area, and vacuum tubes also have disadvantages such as needing to be preheated before use and having a short service life.

The present case provides an audio processing device, which is suitable for receiving an input audio signal and generating an output audio signal according to the input audio signal. The audio processing device includes a controller and a decoder (codec). The controller includes a storage unit, and the storage unit stores a first parameter set and a second parameter set. The controller receives a selection signal, and selects one of the first parameter set and the second parameter set as a control parameter set to output according to the selection signal. The decoder receives the input audio signal, and is electrically coupled to the controller to receive the control parameter set, and converts the input audio signal according to the control parameter set to generate the output audio signal. Among them, the first parameter set is a parameter set corresponding to at least one higher-order harmonic of the output audio signal generated by the enhanced decoder, and the second parameter set is different from the first parameter set.

The invention also provides an audio processing method, which is applicable to a decoder, wherein the decoder receives an input audio signal and converts the input audio signal according to a control parameter set to generate an output audio signal. The audio processing method includes providing a sine wave signal as the input audio signal; finding a first parameter set corresponding to the output audio signal having at least one enhanced high-order sine wave generated by the decoder; and selecting the first parameter set or a second parameter set as the control parameter set according to a selection signal, wherein the second parameter set is different from the first parameter set.

The audio processing device and the audio processing method of the present case can effectively simulate the sound of a vacuum tube by using the first parameter set without using a physical vacuum tube amplifier, thereby effectively reducing the space occupied by the audio processing device and avoiding the problems in use caused by the use of vacuum tubes. Secondly, in addition to the first parameter set, the audio processing device and the audio processing method of the present case also have a second parameter set that can be used to convert input audio into output audio, which is beneficial to provide users with flexibility in selection.

The specific implementation of the present invention will be described in more detail below in conjunction with the schematic diagram. The advantages and features of the present invention will become clearer based on the following description and the scope of the patent application. It should be noted that the diagrams are all in a very simplified form and are not in exact proportions, and are only used to conveniently and clearly assist in explaining the purpose of the present invention.

The first figure is a block diagram of an audio processing device 100 provided according to an embodiment of the present invention. The audio processing device 100 is suitable for being installed in electronic devices with limited internal space such as mobile phones, tablets, and laptops.

As shown in the figure, the audio processing device 100 includes a controller 120 and a codec 140. The audio processing device 100 is adapted to receive an input audio signal S1 and generate an output audio signal S2 according to the input audio signal S1.

The controller 120 includes a storage unit 122. The storage unit 122 stores a first parameter set PS1 and a second parameter set PS2. The first parameter set PS1 is different from the second parameter set PS2. In one embodiment, the controller 120 may be a control chip.

The controller 120 receives a selection signal S3, and selects one of the first parameter set PS1 and the second parameter set PS2 as a control parameter set PSC to be outputted according to the selection signal S3.

The decoder 140 receives the input audio signal S1 and is electrically coupled to the controller 120 to receive the control parameter set PSC. The decoder 140 converts the input audio signal S1 according to the control parameter set PSC to generate the output audio signal S2. The input audio signal S1 is a digital signal. The input audio signal S1 can be from an audio file or a video file. The output audio signal S2 is an analog signal suitable for driving a sound generating device such as a speaker. In one embodiment, the output audio signal S2 may include a left channel analog signal S2L and a right channel analog signal S2R to drive the speaker to generate dual channel sound.

The harmonic compensation parameters of the first parameter set PS1 are used to enhance at least one higher-order harmonic of the output audio signal S2 generated by the decoder 140 , for example, to enhance the second-order harmonic and the third-order harmonic of the output audio signal S2 generated by the decoder 140 .

All the harmonic compensation parameters of the second parameter set PS2 are set to zero, that is, the existing conversion settings of the decoder 140 are maintained. However, this is not limited to this. In other embodiments, the harmonic compensation parameters of the second parameter set PS2 can also be set to weaken at least one high-order harmonic of the output audio signal S2 generated by the decoder 140 to highlight the difference between the first parameter set PS1 and the second parameter set PS2.

Compared to selecting the second parameter set PS2 as the control parameter set PSC, the output audio signal S2 generated by selecting the first parameter set PS1 as the control parameter set PSC will have stronger higher-order harmonics while maintaining the strength of the fundamental wave (or first harmonic wave). In other words, compared to the first parameter set PS1, the output audio signal S2 generated by selecting the second parameter set PS2 as the control parameter set PSC will have weaker higher-order harmonics while maintaining the strength of the fundamental wave (or first harmonic wave).

In one embodiment, the first parameter set PS1 can be set to a parameter set corresponding to the output audio signal S2 having the maximum second harmonic and/or third harmonic generated by the decoder 140 when the input audio signal S1 is a sine wave signal. The first parameter set PS1 can include a left channel second harmonic compensation parameter, a left channel third harmonic compensation parameter, a right channel second harmonic compensation parameter, and a right channel third harmonic compensation parameter, which correspond to the strength of the second and third harmonics of the left channel and the second and third harmonics of the right channel, respectively. The frequency of the sine wave signal is set within the audible frequency range, such as 1kHz.

In one embodiment, the second parameter set PS2 is a parameter set corresponding to the minimum total harmonic distortion (THD) plus noise generated by the decoder 140 when the input audio signal S1 is a sine wave signal. In other words, the second parameter set PS2 is a parameter set that makes the output audio signal S2 match the input audio signal S1 as much as possible.

In one embodiment, the first parameter set PS1 can be set as a default parameter set. When the controller 120 does not receive the selection signal S3, the controller 120 selects the first parameter set PS1 as the control parameter set PSC to be output. The decoder 140 generates the output audio signal S2 according to the first parameter set PS1.

The second figure is a block diagram of an embodiment of the decoder 140 in the first figure. The decoder 140 is suitable for dual-channel audio processing.

As shown in the figure, the decoder 140 includes a register 142 , a modulation unit 144 , a left-channel digital-to-analog conversion unit 146 , and a right-channel digital-to-analog conversion unit 148 .

The register 142 stores a control parameter set PSC. The control parameter set PSC may be the first parameter set PS1 or the second parameter set PS2 from the controller 120.

The modulation unit 144 obtains the control parameter set PSC from the register 142 and adjusts the input audio signal S1 according to the control parameter set PSC to generate a left channel digital signal SDL and a right channel digital signal SDR.

The left channel DAC unit 146 receives the left channel digital signal SDL from the modulation unit 144 and generates a left channel analog signal S2L. The right channel DAC unit 148 receives the right channel digital signal SDR from the modulation unit 144 and generates a right channel analog signal S2R.

The aforementioned left channel analog signal S2L and right channel analog signal S2R are the output audio signal S2, which can be used to drive the speaker directly or be amplified by an amplifier (not shown) and then used to drive the speaker.

The third figure is a flow chart of an audio processing method provided according to an embodiment of the present invention.

This audio processing method is applicable to the audio processing device 100 in the first figure. This audio processing method includes the following steps.

First, as described in step S320, a sine wave signal is provided as an input audio signal S1. Then, as described in step S340, a first parameter set PS1 corresponding to the output audio signal S2 having at least one enhanced high-order sine wave generated by the decoder 140 is found. This setting procedure can be executed by the controller 120 and the decoder 140 in the first figure. In one embodiment, this first parameter set PS1 is stored in the storage unit 122 of the controller 120. In one embodiment, this step is to find the first parameter set PS1 corresponding to the output audio signal S2 having at least one high-order sine wave generated by the decoder 140 with the maximum.

Subsequently, in the audio conversion process, as described in step S360, according to a selection signal S3, the first parameter set PS1 or the second parameter set PS2 is selected as the control parameter set PSC. The second parameter set PS2 is different from the first parameter set PS1. Specifically, this step selects the first parameter set PS1 or the second parameter set PS2 to be stored in the register 142 of the decoder 140 as the control parameter set PSC. In one embodiment, all harmonic compensation parameters of the second parameter set PS2 are set to zero, that is, the existing conversion settings of the decoder 140 are maintained. Step S360 can be executed by the controller 120 in the first figure. Next, the decoder 140 will convert the input audio S1 according to the control parameter set PSC to generate the output audio S2.

FIG. 4 shows an implementation example of step S340 in FIG. 3 .

Following step S320, first, as described in step S420, the register 142 of the decoder 140 is reset to zero. Specifically, the register 142 of the decoder 140 corresponding to the storage position of the control parameter set PSC is reset to zero.

Next, as described in step S440, the secondary harmonic compensation parameter is gradually adjusted and input into the register 142 until the peak of the output audio signal S2 generated by the decoder 140 at the secondary harmonic frequency has the maximum strength. The secondary harmonic compensation parameter may include a left channel secondary harmonic compensation parameter and a right channel secondary harmonic compensation parameter. For example, the value of the secondary harmonic compensation parameter may be gradually increased until the peak at the secondary harmonic frequency is reversed and reduced. The value of the last order before the reversal is the secondary harmonic compensation parameter.

Next, as described in step S460, the cubic harmonic compensation parameter is gradually adjusted and input into the register 142 until the peak of the output audio signal S2 generated by the decoder 140 at the cubic harmonic frequency has the maximum strength. The cubic harmonic compensation parameter may include a left channel cubic harmonic compensation parameter and a right channel cubic harmonic compensation parameter. For example, the value of the cubic harmonic compensation parameter may be gradually increased until the peak inversion at the cubic harmonic frequency is reduced. The value of the last order before the peak inversion is reduced is the cubic harmonic compensation parameter.

The second harmonic compensation parameters and the third harmonic compensation parameters found in the aforementioned steps S440 and S460 can be used as the first parameter set PS1.

In one embodiment, the aforementioned second harmonic compensation parameter and the third harmonic compensation parameter are stored as a byte, that is, eight bits, corresponding to a hexadecimal high-order parameter and a hexadecimal low-order parameter. The adjustment performed in the aforementioned steps S440 and S460 first finds the value corresponding to the high-order parameter, and then finds the value corresponding to the low-order parameter.

Figure 5A shows the waveform of the output audio signal S2 generated by the conversion according to the second parameter set PS2 when the input audio signal S1 is a 1kHz sine wave signal. Figure 5B shows the waveform of the output audio signal S2 generated by the conversion according to the first parameter set PS1 when the input audio signal S1 is a 1kHz sine wave signal. Figure 5C shows the waveform of the output audio signal S2 generated by the vacuum tube conversion when the input audio signal S1 is a 1kHz sine wave signal. The second parameter set PS2 is the parameter set corresponding to the output audio signal S2 with the minimum total harmonic distortion plus noise generated by the decoder 140 when the input audio signal S1 is a sine wave signal. The first parameter set PS1 is the parameter set corresponding to the output audio signal S2 with the maximum second and third harmonics generated by the decoder 140 when the input audio signal S1 is a sine wave signal.

The horizontal axis of the graph is frequency, with the unit being Hz, and the vertical axis is intensity, with the unit being relative decibels (dbr). The graph only shows the left channel of a two-channel audio signal to simplify the explanation.

The waveforms in Figures 5A to 5C have fundamental wave peaks A1, B1, C1 and secondary harmonic peaks A2, B2, C2 at positions corresponding to the fundamental wave frequency (i.e. 1kHz) and the secondary harmonic frequency. The fundamental wave peaks A1, B1, C1 are the highest peaks in the entire waveform.

As shown in the figure, the intensity values of the fundamental wave peak A1 and the secondary harmonic wave peak A2 in Figure 5A are approximately -32 and -95, and the intensity values of the fundamental wave peak B1 and the secondary harmonic wave peak B2 in Figure 5B are approximately -32 and -75. From this point of view, when the intensity of the fundamental wave peaks A1 and B1 are the same, the intensity of the secondary harmonic wave peak A2 in Figure 5A is significantly smaller than the intensity of the secondary harmonic wave peak B2 in Figure 5B. In contrast, the intensity values of the fundamental wave peak C1 and the secondary harmonic wave peak C2 in Figure 5C are similar to the intensity values of the fundamental wave peak B1 and the secondary harmonic wave peak B2 in Figure 5B. Therefore, the output audio S2 generated by the first parameter set PS1 (corresponding to the waveform of Figure 5B) and the output audio S2 generated by the second parameter set PS2 (corresponding to the waveform of Figure 5A) are completely different, and the output audio S2 (corresponding to the waveform of Figure 5B) generated by conversion using the first parameter set PS1 can effectively simulate the sound of the vacuum tube (corresponding to the waveform of Figure 5C).

The audio processing device 100 and the audio processing method of the present case can effectively simulate the sound of a vacuum tube by using a decoder in combination with the first parameter set PS1, without using a physical vacuum tube amplifier, thereby effectively reducing the space occupied by the audio processing device 100 and avoiding the problems in use caused by the use of vacuum tubes. Secondly, in addition to the first parameter set PS1, the audio processing device 100 and the audio processing method of the present case also have a second parameter set PS2 that can be used to convert the input audio signal S1 into the output audio signal S2, which is beneficial to provide users with flexibility in selection.

The above is only the preferred embodiment of this case and does not limit this case in any way. Any technical personnel in the relevant technical field, within the scope of the technical means of this case, make any form of equivalent replacement or modification to the technical means and technical content disclosed in this case, which is within the scope of the technical means of this case and still falls within the scope of protection of this case.

100: Audio processing device

120: Controller

122: Storage unit

140: Decoder

142: Register

144: Modulation unit

146: Left channel digital-to-analog converter

148: Right channel digital-to-analog converter

S1: Input Audio

S2: Output audio

PS1: First parameter set

PS2: Second parameter set

PSC: Control Parameter Group

S3: Select signal

SDL: Left channel digital signal

SDR: right channel digital signal

S2L: Left channel analog signal

S2R: right channel analog signal

S320,S340,S360,S420,S440,S460: Steps

A1, B1, C1: fundamental wave peak

A2, B2, C2: Second harmonic peaks

The first figure is a block diagram of an audio processing device provided according to an embodiment of the present invention; The second figure is a block diagram of an embodiment of the decoder in the first figure; The third figure is a flow chart of an audio processing method provided according to an embodiment of the present invention; The fourth figure shows an embodiment of step S320 in the third figure; The fifth figure A shows a waveform diagram of an output audio generated by conversion according to the second parameter set when the input audio is a 1kHz sine wave signal; The fifth figure B shows a waveform diagram of an output audio generated by conversion according to the first parameter set when the input audio is a 1kHz sine wave signal; and The fifth figure C shows a waveform diagram of an output audio generated by using a vacuum tube device when the input audio is a 1kHz sine wave signal.

100: Audio processing device

120: Controller

122: Storage unit

140: Decoder

S1: Input audio

S2: Output audio

PS1: First parameter set

PS2: Second parameter set

PSC: Control Parameter Group

S3: Select signal

Claims (12)

An audio processing device is suitable for receiving an input audio signal and generating an output audio signal according to the input audio signal. The audio processing device comprises: a controller, comprising a storage unit, the storage unit storing a first parameter set and a second parameter set, the controller receiving a selection signal, and selecting one of the first parameter set and the second parameter set as a control parameter set to be outputted according to the selection signal; a decoder, receiving the input audio signal and electrically coupled to the controller to generate an output audio signal; Receive the control parameter set, and convert the input audio signal according to the control parameter set to generate the output audio signal; wherein the first parameter set is a parameter set corresponding to strengthening at least one higher harmonic of the output audio signal generated by the decoder, and the second parameter set is different from the first parameter set; and wherein all harmonic compensation parameters of the second parameter set are zero, or the second parameter set is a parameter set corresponding to the decoder generating the minimum total harmonic distortion (THD) plus noise when the input audio signal is a sine wave signal. An audio processing device as described in claim 1, wherein the at least one high-order harmonic includes a second-order harmonic and a third-order harmonic. An audio processing device as described in claim 1, wherein the second parameter set corresponds to a parameter set for weakening the at least one higher harmonic of the output audio generated by the decoder. An audio processing device as described in claim 1, wherein the input audio is a digital signal and the output audio is an analog signal. An audio processing device as described in claim 1, wherein the output audio includes a left channel analog signal and a right channel analog signal. The audio processing device as described in claim 5, wherein the decoder comprises: a register storing the control parameter set; a modulation unit obtaining the control parameter set from the register and adjusting the input audio according to the control parameter set to generate a left channel digital signal and a right channel digital signal; a left channel digital-to-analog conversion unit receiving the left channel digital signal and generating the left channel analog signal; and a right channel digital-to-analog conversion unit receiving the right channel digital signal and generating the right channel analog signal. An audio processing device as described in claim 1, wherein the first parameter set includes a left channel second harmonic compensation parameter, a left channel third harmonic compensation parameter, a right channel second harmonic compensation parameter, and a right channel third harmonic compensation parameter. The audio processing device as described in claim 1, wherein the first parameter set is a parameter set corresponding to the output audio signal having at least one maximum high-order sine wave generated by the decoder when the input audio signal is the sine wave signal. An audio processing device as described in claim 8, wherein the frequency of the sine wave signal is 1kHz. An audio processing device as described in claim 1, wherein the first parameter set is a default parameter set. An audio processing method is applicable to a decoder (codec), the decoder receives an input audio signal, and converts the input audio signal according to a control parameter set to generate an output audio signal, the audio processing method comprises: providing a sine wave signal as the input audio signal; finding a first parameter set corresponding to the output audio signal having at least one enhanced high-order sine wave generated by the decoder; and selecting the first parameter set or a second parameter set as the control parameter set according to a selection signal, the second parameter set being different from the first parameter set; wherein all harmonic compensation parameters of the second parameter set are zero, or the second parameter set is a parameter set corresponding to the decoder generating a signal having the minimum total harmonic distortion plus noise. An audio processing method as described in claim 11, wherein the frequency of the sine wave signal is 1 kHz.

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