EEC-492/592 Kinect Application Development

1. EEC-492/592Kinect Application Development Lecture 11 Wenbing Zhao wenbing@ieee.org

2. Outline Using Kinect’s Microphone Array Verifying the Kinect audio configuration The Kinect SDK architecture for audio How Kinect processes audio signals Inside Kinect's microphone array Capturing and playing audio Processing audio data by suppressing and canceling noise Understanding sound source localization and beam formation

3. Verifying the Kinect audio configuration • navigate to Control Panel | Device Manager, look for the Kinect for Windows node, find Kinectfor Windows Audio Array Control • Also check Sound, video and game controllers node Sound driver for microphone array

4. Troubleshooting: Kinect USB Audio not recognizing • While installing the SDK make sure the Kinect device is unplugged • Before using Kinect, restart your system once the installation is done It's always recommended to assign a dedicated USB Controller to the Kinect sensor

5. Using the Kinect microphone array withyour computer Navigate to Control Panel | Sound and switch to the Recording tab, find Kinect'sMicrophone Array as a recording device, set it as default Can test it using Windows sound recorder

6. The Kinect SDK architecture for Audio

7. DirectX Media Object • Controls • Noise Suppression (NS) • AcousticEcho Cancellation (AEC) • Automatic Gain Control (AGC) • SDK exposes a set of Kinect SDK offers APIs to control these above features

8. Major focus area of Kinect audio • Human speech recognition • Recognize player’s voice despite loud noise and echos • Identify the speech within a dynamic range of area • While playing, the player could change his position, or • Multiple players could be speaking from different directions

9. The logic behind placing microphones in different places is to identify the following: The direction of the incoming sound The distance of the sound source => origin of the sound As all the microphones are placed in different positions, the sound will arrive at each of the microphones at different time intervals Why Microphone Array?

10. Audio signal processing in Kinect • Once the source and position of the sound is calculated, the audio-processing pipeline merges the signals of all microphones and produces a signal with high-quality sound • Kinectcan identify the sound within a range of +50 to -50 degrees (NOT radians as stated in the textbook!!!) • KinectAudioSource class • MaxSoundSourceAngle • MinSoundSourceAngle

11. Audio signal processing in Kinect • The SDK fires the SoundSourceAngleChanged event if there is any change in the source angle • The SoundSourceAngleChangedEventArgs class contains two properties: • The current source angle and the confidence that the sound source angle is correct • The sound source angle identifies the direction (not the location) of a sound source • The range of the angle is [-50, +50] degrees • Confidence level • Range: 0.0 (no confidence) to 1.0 (full confidence) • KinectAudioSourceclass has the SoundSourceAngleConfidence property

12. Beam Forming • Like the cone of light from a lighthouse where the light is the brightest, the audio capture hardware has an imaginary cone that is able to capture audio signals the best • Audio waves that propagate through the length of the cone can be separated from audio waves that travel across the cone • If you point the cone in the direction of the audio that your application is most interested in capturing, you can improve the ability to capture and separate that audio source from other competing audio sources • Use the beam angle to set the direction of the imaginary cone to improve your ability to capture a specific audio source

13. Beam Angle • The beam angle identifies a preferred direction for the sensor to listen • The angle is one of the following values (in degrees): {-50, -40, -30, -20, -10, 0, +10, +20, +30, +40, +50} • The sign determines direction: • A negative number indicates the audio source is on the right side of the sensor (left side of the user) • A positive value indicates the audio source is on the left side of the sensor (right side of the user) • 0 indicates the audio source is centered in front of the sensor

14. Sound Source vs. Beam Angle • The sound source angle and the beam angle are both defined from the sensor location. Both angles are defined in the x-z plane of the sensor perpendicular to the z-axis of the sensor. However, the two angles have completely different functionality • Both angles (beam and sound source) are updated continuously once the sensor has started streaming audio data (when the Start method is called) • Use the sound source angle to tell the choose the beam angle if you want to capture a particular sound source

15. Programming Audio Source • Start/stop audio source • The Kinect sensor must be in the running state in order to start the audio stream • If you try to start the audio stream and the sensor is not running, the application will throw an InvalidOperationException • Register sound source angle and beam angle events • Specify audio processing parameters • Manually control beam angle • Recording audio this.sensor.AudioSource.Stop(); this.sensor.AudioSource.Start(); this.sensor.AudioSource.SoundSourceAngleChanged += soundSourceAngleChanged; this.sensor.AudioSource.BeamAngleChanged += beamAngleChanged;

16. Setting Audio Processing Parameters this.sensor.AudioSource.EchoCancellationMode = EchoCancellationMode. CancellationOnly; this.sensor.AudioSource.EchoCancellationSpeakerIndex = 0; this.sensor.AudioSource.NoiseSuppression = true; this.sensor.AudioSource.AutomaticGainControlEnabled = true; • Audio data can be processed by interacting with DMO via KinectAudioSource class • Echo cancellation • CancellationOnly • CancellationAndSuppression • None (default setting) • Noise suppression (enabled by default) • Automatically gain control: amplify weak audio, disabled by default

17. Beam Angle Mode • BeamAngleModel Enumeration • Automatic and Adaptive: Kinect runtime sets the beam angle automatically • Automatic: default setting, use this for a low-volume loudspeaker and/or isotropic background noise • Adaptive: Use this for a high-volume loudspeaker and/or higher noise levels • Manual: The user sets the beam angle to point in the direction of the audio source of interest • The beam angle is located in the xz plane between the z-axis and the direction of an audio source • set the angle using the ManualBeamAngle property this.sensor.AudioSource.BeamAngleMode = BeamAngleMode.Automatic; this.sensor.AudioSource.BeamAngleMode = BeamAngleMode.Manual; // Track the ManualBeamAngle on the right hand position this.sensor.AudioSource.ManualBeamAngle = Math.Atan(rightHand.Position.X / rightHand.Position.Z) * (180 / Math.PI);

18. Recording Audio public void RecordAudio() { int recordingLength = (int)10 * 2 * 16000; byte[] buffer = new byte[1024]; Boolean startAudioStreamHere = false; using (FileStream fileStream = new FileStream(wavfilename, FileMode.Create)) { WriteWavHeader(fileStream, recordingLength); if (audioStream == null) { startAudioStreamHere = true; audioStream = this.sensor.AudioSource.Start(); } int count, totalCount = 0; while ((count = audioStream.Read(buffer, 0, buffer.Length)) > 0 && totalCount < recordingLength) { fileStream.Write(buffer, 0, count); totalCount += count; } if (startAudioStreamHere == true) this.sensor.AudioSource.Stop(); } } • RecordAudio() is blocking

19. Recording Audio private void startBtn_Click(object sender, RoutedEventArgs e) { var audioThread = new Thread(new ThreadStart(RecordAudio)); audioThread.SetApartmentState(ApartmentState.MTA); audioThread.Start(); } To avoid blocking the UI, use thread

20. Recording Audio static void WriteWavHeader(Stream stream, int dataLength) { using (var memStream = new MemoryStream(64)) { int cbFormat = 18; //sizeof(WAVEFORMATEX) WAVEFORMATEX format = new WAVEFORMATEX() { wFormatTag = 1,nChannels = 1, nSamplesPerSec = 16000, nAvgBytesPerSec = 32000, nBlockAlign = 2, wBitsPerSample = 16, cbSize = 0 }; using (var binarywriter = new BinaryWriter(memStream)) { //RIFF header WriteString(memStream, "RIFF"); binarywriter.Write(dataLength + cbFormat + 4); WriteString(memStream, "WAVE"); WriteString(memStream, "fmt "); binarywriter.Write(cbFormat); //WAVEFORMATEX binarywriter.Write(format.wFormatTag); binarywriter.Write(format.nChannels); binarywriter.Write(format.nSamplesPerSec); binarywriter.Write(format.nAvgBytesPerSec); binarywriter.Write(format.nBlockAlign); binarywriter.Write(format.wBitsPerSample); binarywriter.Write(format.cbSize); //data header WriteString(memStream, "data"); binarywriter.Write(dataLength); memStream.WriteTo(stream); } } } struct WAVEFORMATEX { public ushort wFormatTag; public ushort nChannels; public uint nSamplesPerSec; public uint nAvgBytesPerSec; public ushort nBlockAlign; public ushort wBitsPerSample; public ushort cbSize; } static void WriteString(Stream stream, string s) { byte[] bytes = Encoding.ASCII.GetBytes(s); stream.Write(bytes, 0, bytes.Length); } Helper methods

21. Build KinectAudio App Create a new C# WPF project with name KinectAudio Add Microsoft.Kinect reference Design GUI Adding code

22. GUI Design Image MediaElement

23. Adding Code using Microsoft.Kinect; using System.IO; using System.Threading; • Import namespaces • Add member variables: • Register WindowLoaded event handler programmatically KinectSensor sensor; WriteableBitmap colorBitmap; byte[] colorPixels; // Skeleton[] totalSkeleton = new Skeleton[6]; Stream audioStream; string wavfilename = "c:\\temp\\kinectAudio.wav"; public MainWindow() { InitializeComponent(); Loaded += new RoutedEventHandler(WindowLoaded); }

24. Adding Code: WindowLoaded private void WindowLoaded(object sender, RoutedEventArgs e) { this.sensor = KinectSensor.KinectSensors[0]; this.sensor.SkeletonStream.Enable(); this.sensor.ColorStream.Enable(); this.sensor.AllFramesReady += allFramesReady; this.colorPixels = new byte[this.sensor.ColorStream.FramePixelDataLength]; this.colorBitmap = new WriteableBitmap(this.sensor.ColorStream.FrameWidth, this.sensor.ColorStream.FrameHeight, 96.0, 96.0, PixelFormats.Bgr32, null); this.image1.Source = this.colorBitmap; this.sensor.AudioSource.SoundSourceAngleChanged += soundSourceAngleChanged; this.sensor.AudioSource.BeamAngleChanged += beamAngleChanged; // start the sensor. this.sensor.Start(); }

25. Adding Code: AudioStream Start/Stop Stop/start via button clicks private void startAudioStreamBtn_Click(object sender, RoutedEventArgs e) { audioStream = this.sensor.AudioSource.Start(); } private void stopAudioStreamBtn_Click(object sender, RoutedEventArgs e) { this.sensor.AudioSource.Stop(); }

26. Adding Code: Audio Event Handlers void beamAngleChanged(object sender, BeamAngleChangedEventArgs e) { this.soundBeamAngle.Text = e.Angle.ToString(); } void soundSourceAngleChanged(object sender, SoundSourceAngleChangedEventArgs e) { this.soundSourceAngle.Text = e.Angle.ToString(); this.confidenceLevel.Text = e.ConfidenceLevel.ToString(); }

27. Adding Code: AllFramesReady Event Handler void allFramesReady(object sender, AllFramesReadyEventArgs e) { using (ColorImageFrame imageFrame = e.OpenColorImageFrame()) { if (null == imageFrame) return; imageFrame.CopyPixelDataTo(colorPixels); int stride = imageFrame.Width * imageFrame.BytesPerPixel; this.colorBitmap.WritePixels( new Int32Rect(0, 0, this.colorBitmap.PixelWidth, this.colorBitmap.PixelHeight), this.colorPixels, stride, 0); } }

28. Recording/Replay Button Click Events private void startBtn_Click(object sender, RoutedEventArgs e) { var audioThread = new Thread(new ThreadStart(RecordAudio)); audioThread.SetApartmentState(ApartmentState.MTA); audioThread.Start(); } private void playBtn_Click(object sender, RoutedEventArgs e) { if (!string.IsNullOrEmpty(wavfilename) && File.Exists(wavfilename)) { kinectaudioPlayer.Source = new Uri(wavfilename, UriKind.RelativeOrAbsolute); kinectaudioPlayer.LoadedBehavior = MediaState.Play; kinectaudioPlayer.UnloadedBehavior = MediaState.Close; } }

29. Handle Checkbox Events Must register both checked and unchecked event handlers for each checkbox private void noiseSuppression_Checked(object sender, RoutedEventArgs e) { this.sensor.AudioSource.NoiseSuppression = true; } private void echoCancellation_Checked(object sender, RoutedEventArgs e) { this.sensor.AudioSource.EchoCancellationMode = EchoCancellationMode.CancellationOnly; this.sensor.AudioSource.EchoCancellationSpeakerIndex = 0; } private void gainControl_Checked(object sender, RoutedEventArgs e) { this.sensor.AudioSource.AutomaticGainControlEnabled = true; }

30. Handle Checkbox Events private void gainControl_Unchecked(object sender, RoutedEventArgs e) { this.sensor.AudioSource.AutomaticGainControlEnabled = false; } private void echoCancellation_Unchecked(object sender, RoutedEventArgs e) this.sensor.AudioSource.EchoCancellationMode = EchoCancellationMode.None; } private void noiseSuppression_Unchecked(object sender, RoutedEventArgs e) { this.sensor.AudioSource.NoiseSuppression = false; }

31. Challenge Tasks • For advanced students, improve the KinectAudio app in the following ways: • Add ProgressBar for recording and replaying • Draw a vertical line in the color image indicating the audio source angle, and another line indicating the beam angle • Manually specify the beam angle to a particular joint, such as the right hand • Observe the sound source angle with the new beam angle EEC492/693/793 - iPhone Application Development