Patent Application
20240078992
This disclosure relates to audio processing. In particular, this disclosure relates to audio processing of a wind whistle caused by geometry features of a device.
Whistles can be created by device geometry features as the device travels through wind. These whistles can be detected by the microphones of the device and be unpleasant an unnatural in the recorded audio. In an example, a device, such as an image capture device, may include fins for heat dissipation that can create a whistle when wind blows across the fins. Methods for detecting and mitigating the presence of a whistle are needed.
Disclosed herein are implementations of a method and apparatus for detecting and mitigating a wind whistle. In an aspect, an image capture device may include a first microphone, a second microphone, and a processor. The processor may be configured to obtain a first microphone signal from the first microphone. The processor may be configured to obtain a second microphone signal from the second microphone. The processor may be configured to measure coherence values between the first microphone signal and the second microphone signal across a frequency band. The frequency band may include frequency bins. The processor may be configured to measure a coherence value for each frequency bin. The processor may be configured to detect an elevated coherence value in a frequency bin. The elevated coherence value may indicate a presence of a whistle. The processor may be configured to attenuate the frequency bin based on a determination that the elevated coherence value is above a threshold.
In an aspect, a method may include obtaining a first microphone signal from a first microphone. The method may include obtaining a second microphone signal from a second microphone. The method may include measuring coherence values between the first microphone signal and the second microphone signal across a frequency band. The frequency band may include frequency bins. The method may include measuring a coherence value for each frequency bin. The method may include detecting an elevated coherence value in a frequency bin. The elevated coherence value may indicate a presence of a whistle. The method may include attenuating the frequency bin based on a determination that the elevated coherence value is above a threshold.
In an aspect, a non-transitory computer-readable medium may include instructions, that when executed by a processor cause the processor to measure coherence values between a first microphone signal and a second microphone signal across a frequency band. The frequency band may include frequency bins. The processor may measure a coherence value for each frequency bin. The processor may detect an elevated coherence value in a frequency bin. The elevated coherence value may indicate a presence of a whistle. The processor may attenuate the frequency bin based on the elevated coherence value.
The disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not to-scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity.
Devices, such as image capture devices, may include geometry features such as fins for heat dissipation. When wind blows across the fins, the fins can create a whistle that can be detected by one or more of the microphones of the device. The whistle can be an unpleasant and unnatural artifact in the recorded audio.
The implementations described herein include methods and devices configured to detect and attenuate a whistle to provide an improved user experience. The implementations described herein measure a coherence value between two or more microphones. The coherence value is measured per bin and compared against the average coherence value across the full frequency band to detect whether a whistle is present. A whistle is identified when the coherence value of one or more bins deviate from the average coherence value of the full frequency band. Accordingly, it can be determined whether a whistle is present and at which frequency bin the whistle occurs. Based on this information, attenuation can be applied in either the frequency domain by scaling individual bins or in the time domain by adjusting the frequency of a notch filter in real-time.
The image capture device 100 may include an LED or another form of indicator 106 to indicate a status of the image capture device 100 and a liquid-crystal display (LCD) or other form of a display 108 to show status information such as battery life, camera mode, elapsed time, and the like. The image capture device 100 may also include a mode button 110 and a shutter button 112 that are configured to allow a user of the image capture device 100 to interact with the image capture device 100. For example, the mode button 110 and the shutter button 112 may be used to turn the image capture device 100 on and off, scroll through modes and settings, and select modes and change settings. The image capture device 100 may include additional buttons or interfaces (not shown) to support and/or control additional functionality.
The image capture device 100 may include a door 114 coupled to the body 102, for example, using a hinge mechanism 116. The door 114 may be secured to the body 102 using a latch mechanism 118 that releasably engages the body 102 at a position generally opposite the hinge mechanism 116. The door 114 may also include a seal 120 and a battery interface 122. When the door 114 is an open position, access is provided to an input-output (I/O) interface 124 for connecting to or communicating with external devices as described below and to a battery receptacle 126 for placement and replacement of a battery (not shown). The battery receptacle 126 includes operative connections (not shown) for power transfer between the battery and the image capture device 100. When the door 114 is in a closed position, the seal 120 engages a flange (not shown) or other interface to provide an environmental seal, and the battery interface 122 engages the battery to secure the battery in the battery receptacle 126. The door 114 can also have a removed position (not shown) where the entire door 114 is separated from the image capture device 100, that is, where both the hinge mechanism 116 and the latch mechanism 118 are decoupled from the body 102 to allow the door 114 to be removed from the image capture device 100.
The image capture device 100 may include a microphone 128 on a front surface and another microphone 130 on a side surface. The image capture device 100 may include other microphones on other surfaces (not shown). The microphones 128, 130 may be configured to receive and record audio signals in conjunction with recording video or separate from recording of video. The image capture device 100 may include a speaker 132 on a bottom surface of the image capture device 100. The image capture device 100 may include other speakers on other surfaces (not shown). The speaker 132 may be configured to play back recorded audio or emit sounds associated with notifications.
A front surface of the image capture device 100 may include a drainage channel 134. A bottom surface of the image capture device 100 may include an interconnect mechanism 136 for connecting the image capture device 100 to a handle grip or other securing device. In the example shown in
The image capture device 100 may include an interactive display 138 that allows for interaction with the image capture device 100 while simultaneously displaying information on a surface of the image capture device 100.
The image capture device 100 of
The image capture device 100 may include various types of image sensors, such as charge-coupled device (CCD) sensors, active pixel sensors (APS), complementary metal-oxide-semiconductor (CMOS) sensors, N-type metal-oxide-semiconductor (NMOS) sensors, and/or any other image sensor or combination of image sensors.
Although not illustrated, in various embodiments, the image capture device 100 may include other additional electrical components (e.g., an image processor, camera system-on-chip (SoC), etc.), which may be included on one or more circuit boards within the body 102 of the image capture device 100.
The image capture device 100 may interface with or communicate with an external device, such as an external user interface device (not shown), via a wired or wireless computing communication link (e.g., the I/O interface 124). Any number of computing communication links may be used. The computing communication link may be a direct computing communication link or an indirect computing communication link, such as a link including another device or a network, such as the internet, may be used.
In some implementations, the computing communication link may be a Wi-Fi link, an infrared link, a Bluetooth (BT) link, a cellular link, a ZigBee link, a near field communications (NFC) link, such as an ISO/IEC 20643 protocol link, an Advanced Network Technology interoperability (ANT+) link, and/or any other wireless communications link or combination of links.
In some implementations, the computing communication link may be an HDMI link, a USB link, a digital video interface link, a display port interface link, such as a Video Electronics Standards Association (VESA) digital display interface link, an Ethernet link, a Thunderbolt link, and/or other wired computing communication link.
The image capture device 100 may transmit images, such as panoramic images, or portions thereof, to the external user interface device via the computing communication link, and the external user interface device may store, process, display, or a combination thereof the panoramic images.
The external user interface device may be a computing device, such as a smartphone, a tablet computer, a phablet, a smart watch, a portable computer, personal computing device, and/or another device or combination of devices configured to receive user input, communicate information with the image capture device 100 via the computing communication link, or receive user input and communicate information with the image capture device 100 via the computing communication link.
The external user interface device may display, or otherwise present, content, such as images or video, acquired by the image capture device 100. For example, a display of the external user interface device may be a viewport into the three-dimensional space represented by the panoramic images or video captured or created by the image capture device 100.
The external user interface device may communicate information, such as metadata, to the image capture device 100. For example, the external user interface device may send orientation information of the external user interface device with respect to a defined coordinate system to the image capture device 100, such that the image capture device 100 may determine an orientation of the external user interface device relative to the image capture device 100.
Based on the determined orientation, the image capture device 100 may identify a portion of the panoramic images or video captured by the image capture device 100 for the image capture device 100 to send to the external user interface device for presentation as the viewport. In some implementations, based on the determined orientation, the image capture device 100 may determine the location of the external user interface device and/or the dimensions for viewing of a portion of the panoramic images or video.
The external user interface device may implement or execute one or more applications to manage or control the image capture device 100. For example, the external user interface device may include an application for controlling camera configuration, video acquisition, video display, or any other configurable or controllable aspect of the image capture device 100.
The user interface device, such as via an application, may generate and share, such as via a cloud-based or social media service, one or more images, or short video clips, such as in response to user input. In some implementations, the external user interface device, such as via an application, may remotely control the image capture device 100 such as in response to user input.
The external user interface device, such as via an application, may display unprocessed or minimally processed images or video captured by the image capture device 100 contemporaneously with capturing the images or video by the image capture device 100, such as for shot framing or live preview, and which may be performed in response to user input. In some implementations, the external user interface device, such as via an application, may mark one or more key moments contemporaneously with capturing the images or video by the image capture device 100, such as with a tag or highlight in response to a user input or user gesture.
The external user interface device, such as via an application, may display or otherwise present marks or tags associated with images or video, such as in response to user input. For example, marks may be presented in a camera roll application for location review and/or playback of video highlights.
The external user interface device, such as via an application, may wirelessly control camera software, hardware, or both. For example, the external user interface device may include a web-based graphical interface accessible by a user for selecting a live or previously recorded video stream from the image capture device 100 for display on the external user interface device.
The external user interface device may receive information indicating a user setting, such as an image resolution setting (e.g., 3840 pixels by 2160 pixels), a frame rate setting (e.g., 60 frames per second (fps)), a location setting, and/or a context setting, which may indicate an activity, such as mountain biking, in response to user input, and may communicate the settings, or related information, to the image capture device 100.
The image capture device 100 may be used to implement some or all of the techniques described in this disclosure, such as the technique 600 described in
The image capture device 200 includes various indicators on the front of the surface of the body 202 (such as LEDs, displays, and the like), various input mechanisms (such as buttons, switches, and touch-screen mechanisms), and electronics (e.g., imaging electronics, power electronics, etc.) internal to the body 202 that are configured to support image capture via the two camera lenses 204 and 206 and/or perform other imaging functions.
The image capture device 200 includes various indicators, for example, LED 210 to indicate a status of the image capture device 100. The image capture device 200 may include a mode button 212 and a shutter button 214 configured to allow a user of the image capture device 200 to interact with the image capture device 200, to turn the image capture device 200 on, and to otherwise configure the operating mode of the image capture device 200. It should be appreciated, however, that, in alternate embodiments, the image capture device 200 may include additional buttons or inputs to support and/or control additional functionality.
The image capture device 200 may include an interconnect mechanism 216 for connecting the image capture device 200 to a handle grip or other securing device. In the example shown in
The image capture device 200 may include audio components 218, 220, 222 such as microphones configured to receive and record audio signals (e.g., voice or other audio commands) in conjunction with recording video. The audio component 218, 220, 222 can also be configured to play back audio signals or provide notifications or alerts, for example, using speakers. Placement of the audio components 218, 220, 222 may be on one or more of several surfaces of the image capture device 200. In the example of
The image capture device 200 may include an interactive display 224 that allows for interaction with the image capture device 200 while simultaneously displaying information on a surface of the image capture device 200. The interactive display 224 may include an I/O interface, receive touch inputs, display image information during video capture, and/or provide status information to a user. The status information provided by the interactive display 224 may include battery power level, memory card capacity, time elapsed for a recorded video, etc.
The image capture device 200 may include a release mechanism 225 that receives a user input to in order to change a position of a door (not shown) of the image capture device 200. The release mechanism 225 may be used to open the door (not shown) in order to access a battery, a battery receptacle, an I/O interface, a memory card interface, etc. (not shown) that are similar to components described in respect to the image capture device 100 of
In some embodiments, the image capture device 200 described herein includes features other than those described. For example, instead of the I/O interface and the interactive display 224, the image capture device 200 may include additional interfaces or different interface features. For example, the image capture device 200 may include additional buttons or different interface features, such as interchangeable lenses, cold shoes, and hot shoes that can add functional features to the image capture device 200.
The image capture device 200 may be used to implement some or all of the techniques described in this disclosure, such as the technique 600 described in
The image capture device 300 includes a body 302 which includes electronic components such as capture components 310, a processing apparatus 320, data interface components 330, movement sensors 340, power components 350, and/or user interface components 360.
The capture components 310 include one or more image sensors 312 for capturing images and one or more microphones 314 for capturing audio.
The image sensor(s) 312 is configured to detect light of a certain spectrum (e.g., the visible spectrum or the infrared spectrum) and convey information constituting an image as electrical signals (e.g., analog or digital signals). The image sensor(s) 312 detects light incident through a lens coupled or connected to the body 302. The image sensor(s) 312 may be any suitable type of image sensor, such as a charge-coupled device (CCD) sensor, active pixel sensor (APS), complementary metal-oxide-semiconductor (CMOS) sensor, N-type metal-oxide-semiconductor (NMOS) sensor, and/or any other image sensor or combination of image sensors. Image signals from the image sensor(s) 312 may be passed to other electronic components of the image capture device 300 via a bus 380, such as to the processing apparatus 320. In some implementations, the image sensor(s) 312 includes a digital-to-analog converter. A multi-lens variation of the image capture device 300 can include multiple image sensors 312.
The microphone(s) 314 is configured to detect sound, which may be recorded in conjunction with capturing images to form a video. The microphone(s) 314 may also detect sound in order to receive audible commands to control the image capture device 300.
The processing apparatus 320 may be configured to perform image signal processing (e.g., filtering, tone mapping, stitching, and/or encoding) to generate output images based on image data from the image sensor(s) 312. The processing apparatus 320 may include one or more processors having single or multiple processing cores. In some implementations, the processing apparatus 320 may include an application specific integrated circuit (ASIC). For example, the processing apparatus 320 may include a custom image signal processor. The processing apparatus 320 may exchange data (e.g., image data) with other components of the image capture device 300, such as the image sensor(s) 312, via the bus 380.
The processing apparatus 320 may include memory, such as a random-access memory (RAM) device, flash memory, or another suitable type of storage device, such as a non-transitory computer-readable memory. The memory of the processing apparatus 320 may include executable instructions and data that can be accessed by one or more processors of the processing apparatus 320. For example, the processing apparatus 320 may include one or more dynamic random-access memory (DRAM) modules, such as double data rate synchronous dynamic random-access memory (DDR SDRAM). In some implementations, the processing apparatus 320 may include a digital signal processor (DSP). More than one processing apparatus may also be present or associated with the image capture device 300.
The data interface components 330 enable communication between the image capture device 300 and other electronic devices, such as a remote control, a smartphone, a tablet computer, a laptop computer, a desktop computer, or a storage device. For example, the data interface components 330 may be used to receive commands to operate the image capture device 300, transfer image data to other electronic devices, and/or transfer other signals or information to and from the image capture device 300. The data interface components 330 may be configured for wired and/or wireless communication. For example, the data interface components 330 may include an I/O interface 332 that provides wired communication for the image capture device, which may be a USB interface (e.g., USB type-C), a high-definition multimedia interface (HDMI), or a FireWire interface. The data interface components 330 may include a wireless data interface 334 that provides wireless communication for the image capture device 300, such as a Bluetooth interface, a ZigBee interface, and/or a Wi-Fi interface. The data interface components 330 may include a storage interface 336, such as a memory card slot configured to receive and operatively couple to a storage device (e.g., a memory card) for data transfer with the image capture device 300 (e.g., for storing captured images and/or recorded audio and video).
The movement sensors 340 may detect the position and movement of the image capture device 300. The movement sensors 340 may include a position sensor 342, an accelerometer 344, or a gyroscope 346. The position sensor 342, such as a global positioning system (GPS) sensor, is used to determine a position of the image capture device 300. The accelerometer 344, such as a three-axis accelerometer, measures linear motion (e.g., linear acceleration) of the image capture device 300. The gyroscope 346, such as a three-axis gyroscope, measures rotational motion (e.g., rate of rotation) of the image capture device 300. Other types of movement sensors 340 may also be present or associated with the image capture device 300.
The power components 350 may receive, store, and/or provide power for operating the image capture device 300. The power components 350 may include a battery interface 352 and a battery 354. The battery interface 352 operatively couples to the battery 354, for example, with conductive contacts to transfer power from the battery 354 to the other electronic components of the image capture device 300. The power components 350 may also include an external interface 356, and the power components 350 may, via the external interface 356, receive power from an external source, such as a wall plug or external battery, for operating the image capture device 300 and/or charging the battery 354 of the image capture device 300. In some implementations, the external interface 356 may be the I/O interface 332. In such an implementation, the I/O interface 332 may enable the power components 350 to receive power from an external source over a wired data interface component (e.g., a USB type-C cable).
The user interface components 360 may allow the user to interact with the image capture device 300, for example, providing outputs to the user and receiving inputs from the user. The user interface components 360 may include visual output components 362 to visually communicate information and/or present captured images to the user. The visual output components 362 may include one or more lights 364 and/or more displays 366. The display(s) 366 may be configured as a touch screen that receives inputs from the user. The user interface components 360 may also include one or more speakers 368. The speaker(s) 368 can function as an audio output component that audibly communicates information and/or presents recorded audio to the user. The user interface components 360 may also include one or more physical input interfaces 370 that are physically manipulated by the user to provide input to the image capture device 300. The physical input interfaces 370 may, for example, be configured as buttons, toggles, or switches. The user interface components 360 may also be considered to include the microphone(s) 314, as indicated in dotted line, and the microphone(s) 314 may function to receive audio inputs from the user, such as voice commands.
The image capture device 300 may be used to implement some or all of the techniques described in this disclosure, such as the technique 600 described in
Each of the spectrograms 404-408 show sound pressure levels (SPLs) across a frequency range of 0-20,000 Hz. Examples of a detected whistle are visible as faint lines 414-418 (shown inside white circles) when the wind direction 412 is between certain angles across the fins on the rear face of the device 402. As can be seen, while the whistle is most notable in the rear microphone signal, it is also present in the front microphone signal. Detection of a whistle is based on detecting a coherence value between two or more microphones being above a threshold. The measure of the coherence value may be in the frequency domain.
At 604, the method 600 includes obtaining a second microphone signal. The second microphone signal is obtained from a second microphone of the device. The first and second microphones may be disposed on different faces of the device. For example, the first microphone may be disposed on a front face of the device and the second microphone may be disposed on a rear face, side face, or top face of the device. In another example, the first microphone may be disposed on a top face of the device and the second microphone may be disposed on a front face, rear face, or side face of the device.
At 606, the method 600 includes measuring coherence values between the first microphone signal and the second microphone signal. The coherence values may be measured across a frequency band, such as, for example, approximately 20 Hz to approximately 20 kHz. In some examples, the coherence values may be measured across a frequency band that is approximately 0 Hz to approximately 12 kHz. The frequency band may be grouped into frequency bins, and a coherence value may be determined for each frequency bin. Each frequency bin has a width, for example, 93.75 Hz. The width of the frequency bins can be adjusted to any width based on a desired level of sensitivity. The coherence value of each frequency bin is compared against an average of the coherence values across the frequency band.
At 608, the method 600 includes detecting an elevated coherence value in a frequency bin. In some examples, an elevated coherence value may be detected in one or more neighboring frequency bins as well. The elevated coherence value indicates a presence of a whistle when the elevated coherence value is above a threshold. The whistle may be detected in a frequency domain. In an example, the threshold may be a value that is empirically determined based on the average of the coherence values across the frequency band. In another example, the threshold may be a value that is learned offline using an ML algorithm and a training set of whistle and non-whistle data. In some examples, the threshold may be continuously learned and updated in real-time to tailor the whistle detection to a user's specific preferred uses. In some examples, the threshold may be a single value across the frequency band, and in other examples, the threshold may be a discrete value per bin to allow the detector to be more or less sensitive at certain frequencies.
At 610, the method 600 includes attenuating the frequency bin to reduce the detected whistle. The frequency bin is attenuated based on a determination that the elevated coherence value is above the threshold. Examples of whistle attenuation methods are discussed with respect to
At 704, the method 700 includes converting the signal with the whistle amplitude reduced to a time domain signal. The signal with the whistle amplitude reduced may be converted to a time domain signal using an inverse fast Fourier transform (FFT). The signal with the whistle amplitude reduced is converted to a time domain signal in order to make the signal with the whistle amplitude reduced listenable.
At 706, the method 700 includes outputting the time domain signal. The time domain signal may be output for further processing. Further processing of the time domain signal may include dynamics processing, such as adding gain, additional filtering in the time domain, or both.
At 804, the method 800 includes updating a center frequency of a notch filter. For every block of data, it is determined whether a whistle is detected and in which frequency bin it occurred. A new value of whether a whistle was detected or not and a frequency bin in which it occurred is determined at an interval, such as 5 ms. The center frequency of the notch filter can be updated based on the determination of whether a whistle occurred at each interval to track whether the whistle is moving. Updating the center frequency of the notch filter may include updating harmonics, if needed.
At 806, the method 800 includes applying the notch filter to the time domain signal to obtain a filtered signal. The notch filter is used to attenuate one or more frequencies. Applying the notch filter may include applying weights to the time domain signal at one or more frequencies. For example, weights can be applied to one or more frequencies in which a whistle is detected to reduce the whistle such that it is masked by the remaining audio (i.e., general wind sound).
At 808, the method 800 includes outputting the filtered signal. The filtered signal may be output for further processing. Further processing of the time domain signal may include dynamics processing, such as adding gain, additional filtering in the time domain, or both.
While the disclosure has been described in connection with certain embodiments, it is to be understood that the disclosure is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.
