CN105446696A - System and method for restraining blasting noise - Google Patents

Abstract

The invention discloses a system and method for suppressing blasting noise. The system includes: processor MCU, mobile terminal high-definition audio-visual standard interface to red-green-blue MHL? to? RGB chip, codec chip CODEC; the MHL? to? The RGB chip sends the first current audio status signal to the processor MCU; the processor MCU sends the MHL? to? The RGB chip receives the first current audio state signal; and according to the first current audio state signal, judges whether the MHL? to? Whether the first current audio signal output by the RGB chip to the codec chip CODEC is normal; according to the state of the first current audio signal, send the corresponding first processing instruction to the CODEC; the CODEC, from the The processor MCU receives the first processing instruction and performs processing according to the first processing instruction. The invention can suppress the explosion noise of the head-mounted display.

Description

A system and method for suppressing blasting noise

technical field

The invention relates to the audio field, in particular to a system and method for suppressing blasting noise.

Background technique

Popping noise refers to the popping sound produced by the power supply charging the input capacitor, bias capacitor or output DC blocking capacitor when the audio amplifier is powered on, powered off and switched in standby mode. The instantaneous charging of the capacitor often produces a peak voltage at the output terminal, and this voltage is added to both ends of the speaker to generate a current and cut the magnetic force lines, resulting in a force that makes the speaker emit a popping noise.

Head-mounted display is a brand-new technology in modern display technology, which has important applications in enhanced display, virtual realization and stereoscopic display. This head-mounted display is connected to game consoles, tablets, mobile phones, etc. through the standard mobile terminal high-definition audio and video standard interface MHL interface (MHL2.0 protocol), and is presented to end users through the LCD display after passing through the audio/video processing module.

In order to meet the customer's pursuit of high-quality sound, in the head-mounted display, audio noise reduction processing is also required.

Contents of the invention

The invention provides a system and method for suppressing blasting noise, which can effectively suppress blasting noise.

A system for suppressing blast noise comprising:

Processor MCU, mobile terminal high-definition audio-visual standard interface to red, green and blue MHLtoRGB chip, codec chip CODEC;

The MHLtoRGB chip sends a first current audio status signal to the processor MCU;

The processor MCU receives the first current audio state signal from the MHLtoRGB chip; and judges the first current audio state output from the MHLtoRGB chip to the codec chip CODEC according to the first current audio state signal. Whether the audio signal is normal; according to the state of the first current audio signal, send a corresponding first processing instruction to the CODEC;

The CODEC receives the first processing instruction from the processor MCU, and performs processing according to the first processing instruction.

The processor MCU sends a corresponding first processing instruction to the CODEC according to the state of the first current audio signal, specifically:

When the state of the first current audio signal is abnormal, set the working state of the CODEC to a mute state;

When the state of the first current audio signal is normal, it is judged whether the initialization of the CODEC is completed; and corresponding processing is performed according to whether the initialization of the CODEC is completed.

The processor MCU performs corresponding processing according to whether the CODEC completes the initialization, specifically:

When the CODEC is in an uninitialized state, initialize the CODEC; and turn on the volume of the CODEC;

When the state of the CODEC is an initialization completed state, turn on the volume of the CODEC.

The CODEC initialized by the MCU is specifically:

Keeping the CODEC in an abnormal working state by setting the level of the reset pin of the CODEC within the predetermined duration;

Set the rise time of the horizontal DC level output by the headphone jack output channel of the CODEC.

The processor MCU is also used to, when the volume of the CODEC is turned on, receive the second current audio state signal from the MHLtoRGB chip; When the second current audio signal output by the encoder chip CODEC is abnormal, the processor MCU sets the working state of the CODEC to a mute state.

When the second current audio state signal indicates that the second current audio signal output by the MHLtoRGB chip to the codec chip CODEC is abnormal, the processor MCU sets the working state of the CODEC to a mute state, specifically as follows :

The processor MCU sets the level of the reset pin of the CODEC chip, so that the CODEC chip is in a reset state.

A resistor is connected in series with the earphone jack output path of the CODEC.

A method of suppressing blasting noise, comprising:

The processor MCU receives the first current audio state signal from the MHLtoRGB chip; according to the first current audio state signal, it is judged whether the first current audio signal output by the MHLtoRGB chip to the codec chip CODEC is normal; The state of the signal is processed accordingly to the CODEC.

The step of performing corresponding processing on the CODEC according to the state of the first current audio signal includes:

When the state of the first current audio signal is abnormal, the MCU sets the working state of the CODEC to a mute state;

When the state of the first current audio signal is normal, the MCU judges whether the CODEC is initialized; and the MCU performs corresponding processing according to whether the CODEC is initialized.

According to whether the MCU completes the initialization of the CODEC, the steps of performing corresponding processing include:

When the CODEC is in an uninitialized state, the MCU initializes the CODEC; the MCU turns on the volume of the CODEC;

When the state of the CODEC is an initialization completed state, the MCU turns on the volume of the CODEC.

The beneficial effects of the embodiments of the present invention are:

The present invention detects whether the audio signal is normal, and when the state of the first current audio signal is abnormal, sets the working state of the CODEC to a silent state, thereby achieving the purpose of suppressing the popnoise of CODEC blasting noise.

Description of drawings

Fig. 1 is the connection diagram of the system for suppressing blasting noise provided by the embodiment of the present invention;

Fig. 2 is a schematic diagram of the processing flow of the method for suppressing blasting noise provided by an embodiment of the present invention;

Fig. 3 is a system block diagram of the head-mounted display in the application scene of the system for suppressing blasting noise of the present invention;

Fig. 4 is a partial circuit schematic diagram of the application scene of the system for suppressing blasting noise provided by the embodiment of the present invention;

5 is a schematic diagram of the processing flow of the MCU in the system for suppressing blasting noise provided by an embodiment of the present invention;

Fig. 6 is the flowchart of the MHL to RGB chip in the system for suppressing blasting noise provided by the embodiment of the present invention;

FIG. 7 is a flow chart of interrupt processing of the MHL-to-RGB chip in the system for suppressing blasting noise provided by an embodiment of the present invention.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the implementation manner of the present invention will be further described in detail below in conjunction with the accompanying drawings.

As shown in Figure 1, it is a system for suppressing blasting noise according to the present invention, including:

Processor MCU11, mobile terminal high-definition audio-visual standard interface to RGB (MHLtoRGB) chip 12, codec chip CODEC13;

The MHLtoRGB chip 12 sends the first current audio status signal to the processor MCU11;

Said processor MCU11 receives said first current audio state signal from said MHLtoRGB chip; Whether the current audio signal is normal; according to the state of the first current audio signal, send a corresponding first processing instruction to the CODEC13;

The CODEC13 receives the first processing instruction from the processor MCU, and performs processing according to the first processing instruction.

The invention detects whether the audio signal is normal, and configures the CODEC after it is normal, so as to suppress the popnoise of CODEC blasting noise, so that the popnoise cannot be heard in the application of the helmet display, etc., and meets the requirements of product design.

The processor MCU11 sends the corresponding first processing instruction to the CODEC13 according to the state of the first current audio signal, specifically:

When the state of the first current audio signal is abnormal, set the working state of the CODEC to a mute state;

When the state of the first current audio signal is normal, it is judged whether the initialization of the CODEC is completed; and corresponding processing is performed according to whether the initialization of the CODEC is completed.

The processor MCU performs corresponding processing according to whether the CODEC completes the initialization, specifically:

When the CODEC is in an uninitialized state, initialize the CODEC; and turn on the volume of the CODEC;

When the state of the CODEC is an initialization completed state, turn on the volume of the CODEC.

The CODEC initialized by the MCU is specifically:

Keeping the CODEC in an abnormal working state by setting the level of the reset pin of the CODEC within the predetermined duration;

Set the rise time of the horizontal DC level output by the headphone jack output channel of the CODEC.

The processor MCU11 is also used for, when the volume of the CODEC is turned on, the second current audio state signal received from the MHLtoRGB chip; When the second current audio signal output by the encoder chip CODEC is abnormal, the processor MCU sets the working state of the CODEC to a mute state.

When the second current audio state signal indicates that the second current audio signal output by the MHLtoRGB chip to the codec chip CODEC is abnormal, the processor MCU sets the working state of the CODEC to a mute state, specifically as follows :

The processor MCU sets the level of the reset pin of the CODEC chip, so that the CODEC chip is in a reset state.

As shown in FIG. 4 , resistors R1 and R2 are connected in series to the earphone jack output path of the CODEC. That is: connect a resistor in series with the output path of the CODEC to suppress the amplitude of the popnoise. Of course, this will also reduce the maximum volume of the head-mounted display. Therefore, it is necessary to increase the CODEC output volume while simultaneously suppressing popnoise. Select a balanced value between increasing the CODEC output and suppressing the popnoise amplitude, that is, the Popnoise is within an acceptable range, and the maximum output volume is not too low.

As shown in FIG. 4 , R4, C5, and C6 are also arranged on the headphone jack output path of the CODEC, which can better suppress popnoise and obtain better frequency response characteristics.

As shown in Figure 2, it is a kind of method for suppressing blasting noise described in the present invention, comprising:

Step 21, the processor MCU receives the first current audio status signal from the MHLtoRGB chip;

Step 22, according to the first current audio state signal, judge whether the first current audio signal output by the MHLtoRGB chip to the codec chip CODEC is normal;

Step 23, when the state of the first current audio signal is abnormal, the MCU sets the working state of the CODEC to a mute state;

Step 24: When the state of the first current audio signal is normal, the MCU judges whether the CODEC is initialized; and the MCU performs corresponding processing according to whether the CODEC is initialized.

According to whether the MCU completes the initialization of the CODEC, the steps of performing corresponding processing include:

Step 25, when the CODEC is in an uninitialized state, the MCU initializes the CODEC; Step 26, the MCU turns on the volume of the CODEC;

Step 27, when the state of the CODEC is an initialization completed state, the MCU turns on the volume of the CODEC.

The method also includes:

Step 28, judging whether the second current audio status signal received from the MHLtoRGB chip is normal;

Step 29, when the second current audio state signal indicates that the second current audio signal output by the MHLtoRGB chip to the codec chip CODEC is abnormal, the MCU sets the working state of the CODEC to a mute state.

The present invention detects whether the audio signal is normal, and configures the CODEC after it is normal to achieve the purpose of suppressing the CODEC popnoise blasting noise, so that the popnoise cannot be heard in the application of the helmet-mounted display (HMD), which meets the requirements of product design.

The application scenarios of the present invention are described below.

Figure 3 is a logical block diagram of the head-mounted display system, which is mainly composed of MCU5, MHL to RGB chip 2, audio processing unit 3, video processing 4, LCD display 7 and so on. The entire head-mounted display is used as the sink end of the video (terminal display end), responsible for audio and video signal processing and display. Wherein, the audio processing unit 3 can be a TIAIC3104CODEC, which can not only meet the sound quality requirement, but also reduce the cost.

The MCU detects whether there is an audio signal through the MHL to RGB chip 2; when a normal audio signal is detected, the CODEC is configured. When a normal audio signal is not detected, the MCU keeps pulling down the RST (reset) pin of the CODEC, so that the CODEC is in a reset state (abnormal working state). When the reset pin is high, the CODEC is in normal working condition.

That is to say, the present invention judges whether there is an audio signal sent from the source end by configuring an MHL-to-RGB chip (for example, Sii9293ACNUCSiliconImage, hereinafter referred to as 9293). When there is audio signal, configure CODEC. The MCU inquires the status of an MHL-to-RGB chip 2 every predetermined period of time (10ms) through the I2C data bus, so as to obtain the audio status in real time.

Among them, as shown in Figure 5, the processing flow of the MCU that suppresses popnoise includes:

Step 101, MCU initialization, enable CODEC and 9293 (MHL to RGB chip) power control pins, pull down the CODEC reset pin (RST), to prevent the POP sound generated when the CODEC is powered on.

Step 102, the MCU detects whether the audio signal is ready every predetermined time length (for example, 10ms); if the audio signal is not ready, then continue to wait; otherwise enter step 103, judge whether the CODEC is initialized; if the CODEC is not initialized, jump to the step 104; if the CODEC has been initialized, go to step 106.

Step 104, if the CODEC is not initialized, the CODEC reset pin is pulled high, and the delay is 20 milliseconds;

Step 105, initialize the CODEC (configure the charging time of the DC blocking capacitor, etc.). In the present invention, the CODEC is initialized after the clock of the I2S is normal, so that the pop sound generated when the clock is abnormal can be avoided. Specifically: first pull the CODECRST pin high, and then set the register (Register42) to set the rise time of the horizontal DC level. Specifically: For example, set DriverPower-ontimer (signal rise time) to 400ms, DriverRamp-upStepTimingControl (control the charging speed of the output DC bias voltage to the output capacitor) to 4ms, so that the level jumps to the set value within a certain period of time , rather than a steep rising edge. After experimental verification and actual experience, this setting can achieve better results. After the CODEC initialization is complete, plug in the earphones and you can hear the audio from the Source.

Step 106; The output volume of CODEC is set, to open the sound of CODEC, then jump to step 107;

Step 107, circularly check whether the audio signal is normal; if the audio signal is abnormal or there is no audio signal, jump to step 108. If normal, continue testing.

Step 108, if the audio signal is abnormal or there is no audio signal, mute the output of the MuteCODEC. The muteCODEC output is specifically: set the registers Register43 and Register44, and at the same time power down the DAC/HeadphoneDriver (cut off the output DC bias power supply), and optimize and shorten the time from detecting the disconnection of the audio signal to controlling the CODECmute as much as possible.

As shown in Figure 6, the process of MHL to RGB chip (9293) processing includes the following steps:

Step 200, 9293 initialization, configure the output of I2S, configure the PLL clock, open the NewAudioInfoframe interrupt program, that is, when a new AudioInfoframe (audio data packet) is received, an interrupt is generated. Please refer to Figure 5 for the processing flow of the interrupt service program. Clear softmuteflag (this parameter indicates software mute mute processing), set as_AudioOff (this parameter indicates the state after program initialization, ready to process audio data) as the initial state, and set the audio processing flag.

Step 201, check whether the Audioexception is abnormal (check whether the audio is abnormal through AutoAudioControlRegister). If abnormal, close the output of Audio audio data, return to the as_AudioOff state, and clear the audio ready flag.

Step 202, detecting an audio processing flag (AudioProcessflag). If the audio processing flag is set (the audio processing flag is set to 1), then jump to the as_RegAudio (audio register) state;

Step 203, judge whether CTS (CycleTimeStamp: sampling period) is correct (Is_CTS_error); if correct, then jump to step 204; otherwise, jump to step 205.

Step 204, calculate Fs (audio sampling frequency) and MCLK (MasterClock master clock: master clock of I2S) by CTS (CycleTimeStamp: sampling period) and N (number of sampling points) values, calculation formula can refer to formula 1, formula 2. Note that the output MCLK clock is not set at this time, and the MCLK clock is not turned on until SwitchAudioON (turn on audio (clk, data)).

$128\×f\mathrm{the\; s}=\frac{PixelClock\×N}{CTS}$ (Formula 1)

MCLK=Fs×Bits×2 (Formula 2);

Among them, Fs is the audio sampling frequency, CTS (CycleTimeStamp) is the sampling period, N is the number of sampling points, and Pixelclock is the pixel clock; for details, please refer to the MHL or HDMI protocol. AudioclockRegeneration (sound clock generator) Packet (package) z contains sampling period CTS and sampling point number N value information.

Step 205, clear CTSerror (sampling period error flag), (this value must meet certain conditions. For details, refer to the HDMI/MHL protocol specification), and then wait for the next cycle. Currently still in the as_ReqAudio state.

Step 206, check whether the Clock clock is normal through the register of the 9293. If not normal, then jump to the as_RegAudio state, otherwise jump to step 207;

Step 207, turn on the I2S clock and audio data, and set the audio ready flag (SwitchAudioON) at the same time. The MCU judges whether the audio data is normal through the audio ready flag.

Step 208, judge Audiochannelchange (sound channel change (sound sampling package)) (expression Fs (audio sampling frequency) changes when the package content of Audiosamplepackets changes), if yes, then jump to step 209, update audio sampling frequency Fs, otherwise , loop to judge whether there is an Audiochannelchange.

Step 210, when the video mode is not in the VideoON (audio output) state, turn off the Audio audio output (as_AudioOff).

In the present invention, judging the video state can also be performed in an interruption. At present, the head-mounted display only transmits audio when there is a video image.

As shown in Figure 7, the interrupt processing flow of receiving NewAudioInfoFrame includes the following steps:

Step 301, judge whether the received AudioInfoFrame (sound data stream) length and verification are correct;

If correct, then go to step 302, Audioinfoflag (sound flag bit) is set;

Otherwise, jump to step 303, set failpacketflag (fail packet flag bit), and wait for the next interrupt.

Step 304, judging whether it is currently in the as_AudioOn (sound on) state or as_AudioReady (sound is ready) state, if yes, jump to step 305, and update the audio sampling frequency Fs.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present invention are included in the protection scope of the present invention.

Claims (10)

1. suppress a system for noise of blasting, it is characterized in that, comprising:

Processor MCU, mobile terminal high-definition audio and video standard interface turn RGB MHLtoRGB chip, coder chip CODEC;

Described MHLtoRGB chip, sends the first present video status signal to described processor MCU;

Described processor MCU, receives described first present video status signal from described MHLtoRGB chip; And according to described first present video status signal, judge that whether the first current audio signals that described MHLtoRGB chip exports to described coder chip CODEC is normal; When the state of described first current audio signals is abnormal, described first processing instruction is: the duty arranging described CODEC is mute state; When the state of described first current audio signals is normal, described first processing instruction is: judge whether described CODEC completes initialization; And whether complete initialization according to described CODEC and process;

Described CODEC, receives described first processing instruction from described processor MCU, and processes according to described first processing instruction.

2. system according to claim 1, is characterized in that, whether described processor MCU completes initialization according to described CODEC, carries out respective handling and is specially:

When described CODEC is no initializtion state, then CODEC described in initialization; And open the volume of described CODEC;

When described CODEC state is for completing init state, open the volume of described CODEC.

3. system according to claim 2, is characterized in that, described in described MCU initialization, CODEC is specially:

By arranging the level of the reseting pin of described CODEC in reservation duration, CODEC is made to remain abnormal operating state;

The rise time of the horizontal DC level that the earphone jack output channel arranging described CODEC exports.

4. system according to claim 2, is characterized in that, described processor MCU also for, after the volume of opening described CODEC, from the second present video status signal that described MHLtoRGB chip receives; When described second present video status signal represents that described MHLtoRGB chip is abnormal to the second current audio signals that described coder chip CODEC exports, the duty that described processor MCU arranges described CODEC is mute state.

5. system according to claim 4, it is characterized in that, described when described second present video status signal represents that MHLtoRGB chip is abnormal to the second current audio signals that described coder chip CODEC exports, the duty that described processor MCU arranges described CODEC is that mute state is specially:

Described processor MCU arranges the level of the reseting pin of described CODEC chip, makes described CODEC chip be in reset mode.

6. system according to claim 1, is characterized in that,

The earphone jack output channel of described CODEC is connected with resistance.

7. suppress a method for noise of blasting, it is characterized in that, comprising:

Processor MCU receives the first present video status signal from MHLtoRGB chip;

According to described first present video status signal, judge that whether the first current audio signals that MHLtoRGB chip exports to coder chip CODEC is normal;

When the state of described first current audio signals is abnormal, the duty that described MCU arranges described CODEC is mute state;

When the state of described first current audio signals is normal, described MCU judges whether described CODEC completes initialization; Whether described MCU completes initialization according to described CODEC, carries out respective handling.

8. method according to claim 7, is characterized in that, whether described MCU completes initialization according to described CODEC, and the step of carrying out respective handling comprises:

When described CODEC is no initializtion state, then CODEC described in described MCU initialization; Described MCU opens the volume of described CODEC;

When described CODEC state is for complete init state, then described MCU opens the volume of described CODEC.

9. method according to claim 8, is characterized in that, after described MCU opens the step of the volume of described CODEC, described method also comprises:

Judge that whether the second present video status signal received from described MHLtoRGB chip is normal;

When the second present video status signal represents that described MHLtoRGB chip is abnormal to the second current audio signals that described coder chip CODEC exports, the duty that described MCU arranges described CODEC is mute state.

10. method according to claim 9, it is characterized in that, describedly represent that the second current audio signals that MHLtoRGB chip exports to described coder chip CODEC is for time abnormal when described second present video status signal, the duty that described processor MCU arranges described CODEC is that the step of mute state is specially:

Described processor MCU arranges the level of the reseting pin of described CODEC chip, makes described CODEC chip be in reset mode.