Audio mixing device and audio mixing method

Abstract

The present application relates to an audio mixing device, comprising an audio codec circuit, an output buffer group, a DC shift buffer group, and an audio port. The output buffer group is coupled to a first pair of pins and is configured to output an audio source output signal to the first pair of pins. The DC shift buffer group is coupled between the audio codec circuit and the first pair of pins and is directly coupled to the output buffer group and the first pair of pins. The audio port is coupled to the first pair of pins. The DC shift buffer group is configured to receive a first audio source input signal from the audio port via the first pair of pins. The audio codec circuit is configured to replay the audio source output signal via the DC shift buffer group and mix the replayed audio source output signal with a second audio source input signal.

Description

Technical Field

[0001] The embodiments described in the present invention relate to an audio mixing technology, and more particularly to an audio mixing device and an audio mixing method. Background Art

[0002] With the development of audio technology, many electronic devices have an audio mixing (abbreviated as mixing) function. For example, many electronic devices can play music and record it back, and mix the recorded music with the singing voice input by the user through a microphone.

[0003] However, in some related technologies, the input buffer and output buffer in these electronic devices are respectively coupled to different pairs of pins, and an AC coupling capacitor is required between the audio port and the pair of pins of the input buffer to prevent the operating voltage of the input buffer from being pulled to an abnormal potential by other potentials (e.g., ground potential). Summary of the Invention

[0004] Some embodiments of the present invention relate to an audio mixing device. The audio mixing device includes an audio codec circuit, an output buffer group, a DC shift buffer group, and an audio port. The output buffer group is coupled to a first pair of pins and is used to output an audio source output signal to the first pair of pins. The DC shift buffer group is coupled between the audio codec circuit and the first pair of pins and is directly coupled to the output buffer group and the first pair of pins. The audio port is coupled to the first pair of pins. The DC shift buffer group is used to receive a first audio source input signal from the audio port via the first pair of pins. The audio codec circuit is used to replay the audio source output signal and mix the replayed audio source output signal with the first audio source input signal.

[0005] Some embodiments of the present invention relate to an audio mixing method. The audio mixing method includes the following operations: outputting an audio source output signal to a first pair of pins via an output buffer group in an audio mixing device; receiving a first audio source input signal from an audio port via a DC shift buffer group in the audio mixing device, wherein the DC shift buffer group is directly coupled to the output buffer group and the first pair of pins; and re-recording the audio source output signal via an audio codec circuit in the audio mixing device and mixing the re-recorded audio source output signal with the first audio source input signal.

[0006] In summary, the audio mixing device of the present invention includes a DC shift buffer group that can offset the DC voltage, thereby preventing the DC shift buffer's operating voltage from being pulled to an abnormal potential by other potentials (e.g., ground potential). Consequently, the present invention eliminates the need for AC coupling capacitors. Furthermore, the DC shift buffer group and the output buffer group can share pins, reducing the pin count. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] To make the above and other objects, features, advantages and embodiments of the present invention more apparent, the following descriptions of the accompanying drawings are given:

[0008] Figure 1 is a circuit diagram of an audio mixing device according to some embodiments of the present invention;

[0009] Figure 2 is a circuit diagram of an audio codec circuit according to some embodiments of the present invention;

[0010] Figure 3 is a schematic diagram of one of the DC shift buffers according to some embodiments of the present invention;

[0011] Figure 4 is a schematic diagram of a frequency response of a DC shift buffer according to some embodiments of the present invention;

[0012] Figure 5 is a schematic diagram of frequency response of a buffer coupled to an AC coupling capacitor in some related technologies; and

[0013] Figure 6 is a flowchart of an audio mixing method according to some embodiments of the present invention. DETAILED DESCRIPTION

[0014] The following detailed description of the embodiments is accompanied by accompanying drawings. However, the embodiments provided are not intended to limit the scope of the present invention, and the description of the structure and operation is not intended to limit the order of execution. Any device with equivalent functionality resulting from the reconfiguration of the components is within the scope of the present invention. Furthermore, the drawings are for illustrative purposes only and are not drawn to scale. To facilitate understanding, identical or similar components will be designated by the same reference numerals throughout the following description.

[0015] As used herein, the term “coupled” may also refer to “electrically coupled,” and the term “connected” may also refer to “electrically connected.” “Coupled” and “connected” may also refer to two or more elements cooperating or interacting with each other.

[0016] refer to Figure 1 . Figure 1is a circuit diagram of an audio mixing device 100 according to some embodiments of the present invention. The audio mixing device 100 can cooperate with a sound source output / input device to play audio and record audio back, and mix the recorded audio with external audio input. For example, the audio mixing device 100 can play a piece of music through the sound source output device and record it back through the sound source input device, and mix the recorded music with the human voice input by the user through a microphone (which can be a type of sound source input device). In some embodiments, the audio mixing device 100 can be set in a mobile phone, laptop, or other electronic device with a recording function.

[0017] by Figure 1 For example, the audio mixing device 100 includes an audio codec (CODEC) circuit 102, a DC shift buffer group 104 (corresponding to the left and right channels, respectively), an output buffer group 106 (corresponding to the left and right channels, respectively), an input buffer group 108 (corresponding to the left and right channels, respectively), a switch circuit 110, an audio port AJ, a first pair of pins P1 (corresponding to the left and right channels, respectively), a second pair of pins P2 (corresponding to the left and right channels, respectively), a third pair of pins P3 (corresponding to the left and right channels, respectively), and a fourth pair of pins P4 (corresponding to the left and right channels, respectively), a pair of resistors RS1 (corresponding to the left and right channels, respectively), and another pair of resistors RS2 (corresponding to the left and right channels, respectively). The audio codec circuit 102 includes an analog-to-digital front-end circuit FE.

[0018] In terms of coupling, the DC shift buffer set 104 is coupled between the analog-to-digital conversion front-end circuit FE and the first pair of pins P1. The input of the DC shift buffer set 104 is directly coupled to the output of the output buffer set 106 and the first pair of pins P1. As shown in the figure, the DC shift buffer set 104 is coupled to the line connecting the output buffer set 106 and the first pair of pins P1. The output of the output buffer set 106 is coupled to the first pair of pins P1. The first pair of pins P1 is coupled to the audio port AJ. As shown in the figure, the first pair of pins P1 is coupled to the inner terminals of the audio port AJ. The input buffer set 108 is coupled between the analog-to-digital conversion front-end circuit FE and the switch circuit 110. Specifically, the output of the input buffer set 108 is coupled to the analog-to-digital conversion front-end circuit FE, while the input of the input buffer set 108 is coupled to the switch circuit 110. The switch circuit 110 is coupled to the second pair of pins P2. The second pair of pins P2 is coupled to audio port AJ. As shown in the figure, the second pair of pins P2 is coupled to the two outer terminals of audio port AJ. Audio port AJ is coupled to the third pair of pins P3 via resistor RS2. As shown in the figure, the third pair of pins P3 is coupled to the two outer terminals of audio port AJ. The fourth pair of pins P4 is coupled to the output terminals of output buffer set 106 and the first pair of pins P1 via the pair of resistors RS1. As shown in the figure, the fourth pair of pins P4 is coupled to the line connecting output buffer set 106 and the first pair of pins P1.

[0019] In operation, the audio mixing device 100 can output an audio output signal AO1 to the audio port AJ, allowing the audio output device connected to the audio port AJ to output sound corresponding to the audio output signal AO1. The audio output signal AO1 may include, but is not limited to, a musical signal. For example, the output buffer set 106 can output the audio output signal AO1 to the audio port AJ via the first pair of pins P1. At this point, the audio output signal AO1 is recorded back by the audio codec circuit 102 via the DC shift buffer set 104. Specifically, the audio output signal AO1 from the output buffer set 106 is transmitted back by the DC shift buffer set 104 to the analog-to-digital conversion front-end circuit FE in the audio codec circuit 102.

[0020] In some embodiments, the user can listen to music (corresponding to the audio output signal AO1) output by an audio output device (e.g., headphones) connected to the audio port AJ or other audio output devices (e.g., speakers connected to a Figure 1 The user can sing (which may correspond to the music of the sound source output signal AO1) to the sound source input device (such as a microphone) connected to the audio port AJ, so that the sound source input device generates the corresponding sound source input signal AS1 or sound source input signal AS2.

[0021] In some embodiments, the audio input device is, for example, a three-ring microphone. When a driver (not shown, providing a voltage) applies a bias voltage to the two wires corresponding to the first pair of pins P1 in the audio port AJ via the fourth pair of pins P4 and the resistor RS1, the audio input signal AS1 corresponding to the three-ring microphone can be transmitted from the audio port AJ through the first pair of pins P1 to the DC shift buffer 104, and then input into the analog-to-digital conversion front-end circuit FE.

[0022] In some embodiments, the audio input device is, for example, a four-ring headphone microphone. When the driver applies a bias voltage to the two wires corresponding to the second pair of pins P2 in the audio port AJ via the third pair of pins P3 and the resistor RS2, the audio input signal AS2 corresponding to the four-ring headphone microphone can be transmitted from the audio port AJ through the second pair of pins P2 and the switch circuit 110 to the input buffer 108, and then input to the analog-to-digital front-end circuit FE.

[0023] In some embodiments, the analog-to-digital front-end circuit FE in the audio codec circuit 102 may re-record (via the DC shift buffer group 104 ) the audio output signal AO1 and the audio input signal AS2 from the output buffer group 106 for mixing.

[0024] refer to Figure 1 as well as Figure 2 . Figure 2 FIG. 1 is a circuit diagram of the audio codec circuit 102 according to some embodiments of the present invention. Figure 2 For example, the audio codec circuit 102 includes a digital interface DI, volume control circuits 1211-1214 (four circuits adjacent to the digital interface DI in the figure), filter circuits 1221-1224 (four circuits connected to the volume control circuits 1211-1214 in the figure), digital-to-analog conversion circuits 1231-1232 (two circuits connected to the filter circuits 1221-1222 in the figure), analog-to-digital conversion circuits 1233-1234 (two circuits connected to the filter circuits 1223-1224 in the figure), multiplexers 1241-1242, mute controllers 1251-1252, volume control circuits 1261-1263, and analog-to-digital conversion front-end circuits FE1-FE2.

[0025] The volume control circuits 1211-1212, the filter circuits 1221-1222, and the digital-to-analog conversion circuits 1231-1232 form a playback path, while the volume control circuits 1213-1214, the filter circuits 1223-1224, and the analog-to-digital conversion circuits 1233-1234 form a record path.

[0026] In some embodiments, the digital interface DI can be an HDD interface, an I2S interface, a USB interface, or any other interface capable of transmitting audio signals. In some embodiments, the volume control circuits 1211-1214 can include a volume controller and a mute controller, respectively. In some embodiments, the filter circuits 1221-1222 are oversampling filters, and the filter circuits 1223-1224 are downsampling filters.

[0027] In operation, digital interface DI is used to receive a digital audio source signal. Volume control circuit 1211 (or 1212) is a digital volume control circuit in the audio output path. It is coupled to digital interface DI and is used to adjust the volume of the digital audio source signal (generally, volume control here involves attenuation. With the digital audio source as the reference, the volume control range of volume control circuit 1211 (or 1212), for example, is 0dB to -30dB) and control whether to mute the digital audio source signal. Filter circuit 1221 (or 1222) is coupled to volume control circuit 1211 (or 1212) and is used to filter the digital audio source signal adjusted by volume control circuit 1211 (or 1212). Digital-to-analog conversion circuit 1231 (or 1232) is coupled to filter circuit 1221 (or 1222) and is used to convert the filtered digital audio source signal into an analog audio source signal LOUT1 (or LOUT2). Multiplexer 1241 is coupled to digital-to-analog conversion circuits 1231 and 1232 and is controlled by a selection signal (not shown) to select and output either analog audio signal LOUT1 or analog audio signal LOUT2. A mute controller 1251 is coupled to multiplexer 1241 and controls whether to mute the audio signal output by multiplexer 1241. Output buffer 106 then outputs analog audio signal LOUT1 (or LOUT2) from mute controller 1251 as audio output signal AO1.

[0028] In some embodiments, a mixing circuit (not shown) may be provided between the multiplexer 1241 and the mute controller 1251 to mix the output of the multiplexer 1241 with audio source signals from other paths.

[0029] Volume control circuit 1261 can be used to control the volume of the replay source output signal AO1 from the DC shift buffer group 104 or the audio source input signal AS1 (e.g., from a three-ring microphone) from the DC shift buffer group 104. Volume control circuit 1262 can be used to control the volume of the audio source input signal AS3 from another chip or other electronic device. Volume control circuit 1263 can be used to control the volume of the audio source input signal AS2 (e.g., from a four-ring headphone microphone). Volume control circuits 1261-1263 are analog volume control circuits in the audio input path. Because the signal transmitted from the audio input device is relatively weak, the volume control here is generally enhanced. The volume control range of volume control circuits 1261-1263 is, for example, +10dB / 20dB / 30dB. Next, the analog-to-digital conversion front-end circuit FE1 (or FE2) can be configured to receive a volume-controlled audio output signal AO1, a volume-controlled audio input signal AS1, a volume-controlled audio input signal AS2, or a volume-controlled audio input signal AS3. The analog-to-digital conversion front-end circuit FE1 (or FE2) can mix the audio output signal AO1 with the audio input signal AS2 (i.e., mixing the recorded audio with the audio from the four-ring microphone), or mix the audio output signal AO1 with the audio input signal AS3 (i.e., mixing the recorded audio with the audio from another chip or other electronic device). In some embodiments, the analog-to-digital conversion front-end circuit FE1 (or FE2) includes an audio mixing circuit.

[0030] The analog-to-digital conversion circuit 1233 (or 1234) is coupled to the analog-to-digital conversion front-end circuit FE1 (or FE2) and is configured to convert the analog mixed audio source signal from the analog-to-digital conversion front-end circuit FE1 (or FE2) into a digital mixed audio source signal. The filter circuit 1223 (or 1224) is coupled to the analog-to-digital conversion circuit 1233 (or 1234) and is configured to filter the digital mixed audio source signal from the analog-to-digital conversion circuit 1233 (or 1234). Volume control circuit 1213 (or 1214) is coupled to filter circuit 1223 (or 1224). Volume control circuit 1213 (or 1214) is a digital volume control circuit on the audio input path. It is used to adjust the volume of the filtered digital mixed audio source signal (generally speaking, due to the relatively variable volume of the front-end analog audio source, the volume control here can be boost / attenuation. The volume control range of volume control circuit 1211 (or 1212) is, for example, -30dB to +30dB), control whether to mute it, and transmit the adjusted audio source signal to the digital interface DI.

[0031] Multiplexer 1242 is configured to receive analog audio signal LOUT1 and analog audio signal LOUT2 (equivalent to the signal input to multiplexer 1241). Multiplexer 1242 is controlled by a selection signal to output one of the analog audio signal LOUT1 or analog audio signal LOUT2. In some embodiments, in addition to analog audio signal LOUT1 and analog audio signal LOUT2, multiplexer 1242 also receives an average audio signal of the left and right channels of analog audio signal LOUT2 (or LOUT1), but the present invention is not limited to this. Mute controller 1252 is configured to receive an audio signal from multiplexer 1242 and control whether to mute the audio signal output by multiplexer 1242. Based on this audio signal, multiplexer 1242 outputs audio output signal AO2 to another chip or other electronic device (e.g., the other audio output device described above).

[0032] refer to Figure 3 . Figure 3 FIG is a schematic diagram of one DC shift buffer of the DC shift buffer group 104 according to some embodiments of the present invention. Figure 3 For example, a DC shift buffer in the DC shift buffer group 104 may include an AC signal source 1041, a buffer circuit 1042, a resistor R1, and a resistor R2. The AC signal source 1041 is coupled between a ground terminal GND and the resistor R1. The AC signal source 1041 is configured to output an AC signal AC1. The resistor R1 is coupled between the AC signal source 1041 and a first input terminal (e.g., a positive input terminal) of the buffer circuit 1042. The buffer circuit 1042 is configured to receive a DC voltage VDD (e.g., but not limited to, 5 volts) and operate based on the DC voltage VDD. The output terminal of the buffer circuit 1042 is configured to output an output signal AC2. The output terminal of the buffer circuit 1042 is also coupled to a second input terminal (e.g., a negative input terminal) of the buffer circuit 1042 to form a negative feedback structure. The resistor R2 is coupled to the first input terminal (e.g., a positive input terminal) of the buffer circuit 1041 and is configured to receive the DC voltage VDD.

[0033] exist Figure 3 In the configuration, resistors R1 and R2 form a voltage divider circuit. In some embodiments, the resistance value of resistor R1 can be the same as the resistance value of resistor R2, but the present invention is not limited thereto. In an embodiment where the resistance value of resistor R1 is the same as the resistance value of resistor R2, if the DC voltage VDD is 5 volts, the AC signal AC1 will be DC-shifted to 2.5 volts.

[0034] In some related technologies, the input buffer group and the output buffer group are coupled to different pairs of pins respectively, and an AC coupling capacitor is required to be set between the audio port and the pair of pins of the input buffer to prevent the operating voltage of the input buffer from being pulled to an abnormal potential by other potentials (e.g., ground potential).

[0035] Compared to the aforementioned related arts, in the present invention, the DC shift buffer group 104 and the output buffer group 106 can share pins (e.g., the first pair of pins P1). This reduces the number of pins and the number of traces on the printed circuit board (PCB), and also eliminates some input signal traces. Furthermore, the DC shift buffer group 104 can offset the DC voltage, thereby preventing the operating voltage of the DC shift buffer group 104 from being pulled to an abnormal potential by other potentials (e.g., ground potential). Consequently, the present invention eliminates the need for AC capacitors on the PCB, thereby reducing the overall area.

[0036] On the other hand, the present invention can enhance the frequency response of the DC shift buffer group 104. Figure 4 . Figure 4 FIG is a diagram showing the frequency response of the DC shift buffer group 104 according to some embodiments of the present invention. Figure 4 The implementation example shows that the frequency response of the DC shift buffer group 104 does not have a significant attenuation between 20-20 kHz.

[0037] refer to Figure 5 . Figure 5 Figure 1 is a diagram showing the frequency response of a buffer coupled to an AC coupling capacitor in some related technologies. Figure 5 For example, the frequency response of a buffer coupled to an AC coupling capacitor has a rolloff in the low-frequency portion. Compared to a buffer coupled to an AC coupling capacitor with a capacitance of 1 μF, the frequency response of a buffer coupled to an AC coupling capacitor with a capacitance of 0.1 μF has a more significant rolloff in the low-frequency portion.

[0038] refer to Figure 6 . Figure 6 FIG. 6 is a flow chart of an audio mixing method 600 according to some embodiments of the present invention. In some embodiments, the audio mixing method 600 is applied to Figure 1 The audio mixing device 100 in FIG. Figure 6 For example, the audio mixing method 600 includes operations S610 , S620 , and S630 .

[0039] In operation S610, the audio source output signal AO1 is output to the first pair of pins P1 via the output buffer group 106 in the audio mixing device 100. The audio source output signal AO1 is, for example, music.

[0040] In operation S620, the DC shift buffer group 104 in the audio mixing device 100 receives an audio input signal AS1 from the audio port AJ via the first pair of pins P1, or receives an audio input signal AS2 from the audio port AJ via the second pair of pins P2 via the input buffer group 108. The audio input signals AS1 and AS2 may be, for example, a user's singing voice.

[0041] In operation S630, the audio codec circuit 102 in the audio mixing device 100 replays the source output signal AO1, and the analog-to-digital conversion front-end circuit FE in the audio codec circuit 102 can mix the replayed source output signal AO1 with the source input signal AS2. For example, the DC shift buffer group 104 can receive the source output signal AO1 output by the output buffer group 106 and transmit the source output signal AO1 to the audio codec circuit 102 to complete the replay. The audio codec circuit 102 then mixes the replayed source output signal AO1 with the source input signal AS2. Alternatively, the DC shift buffer group 104 can receive the source input signal AS1 from the audio port AJ.

[0042] It should be noted that the multiple operations of the audio mixing method 600 described above are merely examples and are not necessarily performed in the order shown in this example. The various operations of the audio mixing method 600 may be appropriately added, replaced, omitted, or performed in a different order without departing from the scope and operation of the embodiments of the present invention.

[0043] In summary, the audio mixing device of the present invention includes a DC shift buffer group that can offset the DC voltage, thereby preventing the DC shift buffer group's operating voltage from being pulled to an abnormal potential by other potentials (e.g., ground potential). Consequently, the present invention eliminates the need for AC coupling capacitors. Furthermore, the DC shift buffer group and the output buffer group can share pins, reducing the number of pins.

[0044] Although the present invention has been disclosed above through the implementation methods, this is not intended to limit the present invention. Any technician with ordinary knowledge in the field can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

[0045] Description of reference numerals:

[0046] 100: Audio mixing device

[0047] 102: Audio codec circuit

[0048] 1211, 1212, 1213, 1214: Volume control circuit

[0049] 1221, 1222, 1223, 1224: Filter circuit

[0050] 1231, 1232: Digital-to-analog conversion circuit

[0051] 1233, 1234: Analog-to-digital conversion circuit

[0052] 1241, 1242: Multiplexers

[0053] 1251, 1252: Mute controller

[0054] 1261, 1262, 1263: Volume control circuit

[0055] 104: DC shift buffer group

[0056] 1041: AC signal source

[0057] 1042: Buffer circuit

[0058] 106: Output buffer group

[0059] 108: Input buffer group

[0060] 110: Switching Circuit

[0061] 600: Audio Mixing Methods

[0062] FE, FE1, FE2: Analog-to-digital conversion front-end circuit

[0063] AJ: Audio port

[0064] P1: first pair of pins

[0065] P2: The second pair of pins

[0066] P3: The third pair of pins

[0067] P4: The fourth pair of pins

[0068] RS1: resistor

[0069] RS2: resistor

[0070] AS1, AS2, AS3: audio source input signal

[0071] AO1, AO2: audio source output signal

[0072] DI: Digital Interface

[0073] AC1: AC signal

[0074] AC2: output signal

[0075] R1: resistor

[0076] R2: resistor

[0077] GND: ground terminal

[0078] VDD: DC voltage

[0079] LOUT1, LOUT2: analog audio source signal

[0080] S610, S620, S630: Operation

Claims

1. An audio mixing device, comprising: an audio codec circuit; an output buffer set coupled to a first pair of pins and configured to output an audio output signal to the first pair of pins; a DC shift buffer group coupled between the audio codec circuit and the first pair of pins, and directly coupled to the output buffer group and the first pair of pins; and an audio port coupled to the first pair of pins, wherein the DC shift buffer group is used to receive a first audio source input signal from the audio port through the first pair of pins; The audio codec circuit is used to record back the audio source output signal through the DC shift buffer group and mix the recorded audio source output signal with a second audio source input signal.

2. The audio mixing device according to claim 1, wherein The DC shift buffer group includes: an AC signal source; a buffer circuit having a first input terminal, a second input terminal, and an output terminal, wherein the output terminal is coupled to the second input terminal, and the buffer circuit is configured to receive a DC voltage; a first resistor coupled between the AC signal source and a first input terminal of the buffer circuit; and A second resistor is coupled to the first input terminal and is used to receive the DC voltage.

3. The audio mixing device according to claim 1, wherein The third audio source input signal comes from a chip or electronic device outside the audio mixing device.

4. The audio mixing device according to claim 1, wherein A bias voltage is applied to the two wires of the audio port corresponding to the first pair of pins, so that the first audio source input signal is transmitted from the audio port through the first pair of pins to the DC shift buffer group and then input to the audio codec circuit.

5. The audio mixing device according to claim 1, wherein Also includes: a second pair of pins coupled to the audio port; a switch circuit coupled to the second pair of pins; as well as an input buffer group coupled between the switch circuit and the audio codec circuit, The second audio source input signal is transmitted from the audio port through the second pair of pins and the switch circuit to the input buffer group, and then input to the audio codec circuit.

6. The audio mixing device according to claim 5, characterized in that Also includes: a third pair of pins coupled to the audio port via a pair of resistors, The audio codec circuit applies a bias voltage to two wires corresponding to the second pair of pins in the audio port through the third pair of pins and the pair of resistors, so that the second audio source input signal is input into the audio codec circuit.

7. The audio mixing device according to claim 1, wherein: The audio codec circuit includes a playback path and a recording path. The playback path is used to output the audio source output signal, and the recording path is used to input the first audio source input signal into the audio codec circuit.

8. The audio mixing device according to claim 7, characterized in that The recording path includes: an analog-to-digital conversion circuit; and a first filtering circuit coupled to the analog-to-digital conversion circuit, The first audio source input signal is transmitted to a digital interface in the audio codec circuit through the analog-to-digital conversion circuit and the first filter circuit.

9. The audio mixing device according to claim 8, characterized in that The playback path includes: a digital-to-analog conversion circuit; and a second filtering circuit coupled to the digital-to-analog conversion circuit, The audio source output signal output from the digital interface is transmitted to the DC shift buffer group through the second filter circuit and the digital-to-analog conversion circuit.

10. An audio mixing method, comprising: Outputting an audio source output signal to a first pair of pins through an output buffer group in an audio mixing device; receiving a first audio source input signal from an audio port through the first pair of pins via a DC shift buffer set in the audio mixing device, wherein the DC shift buffer set is directly coupled to the output buffer set and the first pair of pins; and The audio source output signal is recorded back through the DC shift buffer group by an audio codec circuit in the audio mixing device, and the recorded audio source output signal and a second audio source input signal are mixed.

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