io.spokestack.spokestack.webrtc

Class VoiceActivityDetector

java.lang.Object

io.spokestack.spokestack.webrtc.VoiceActivityDetector

All Implemented Interfaces:

SpeechProcessor, AutoCloseable

public class VoiceActivityDetector
extends Object
implements SpeechProcessor

Voice Activity Detection (VAD) pipeline component

VoiceActivityDetector is a speech pipeline component that implements Voice Activity Detection (VAD) using the webrtc native component. The detector processes each frame and sets the speech context to speech/nonspeech based on the results of the VAD algorithm. The VAD implementation is based on the webrtc VAD in the Chromium browser. It supports 16-bit PCM samples.

This pipeline component supports the following configuration properties:

• sample-rate (int): audio sample rate, in Hz (supports 8000/16000/32000/48000Hz)
• frame-width (int): audio frame width, in ms (supports 10/20/30ms)
• vad-mode (string): detector mode, one of the following:
  • quality: highest recall
  • low-bitrate: higher recall
  • aggressive: higher precision
  • very-aggressive: highest precision
• vad-rise-delay (int): rising-edge detection run length, in ms; this value determines how many positive samples must be received to flip the detector to positive
• vad-fall-delay (int): falling-edge detection run length, in ms; this value determines how many negative samples must be received to flip the detector to negative

The detector uses a simple consecutive value filter to eliminate noisy transitions.

Field Summary

Fields

Modifier and Type	Field and Description
static String	DEFAULT_MODE default voice detection mode (high precision).

Constructor Summary

Constructors

Constructor and Description
VoiceActivityDetector(SpeechConfig config) constructs a new trigger instance.

Method Summary

Modifier and Type	Method and Description
void	close() destroys the unmanaged VAD instance.
void	process(SpeechContext context, ByteBuffer frame) processes a frame of audio.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEFAULT_MODE

public static final String DEFAULT_MODE

default voice detection mode (high precision).

See Also:

Constant Field Values

Constructor Detail

VoiceActivityDetector

public VoiceActivityDetector(SpeechConfig config)

constructs a new trigger instance.

Parameters:

config - the pipeline configuration instance

Method Detail

close

public void close()

destroys the unmanaged VAD instance.

Specified by:

close in interface AutoCloseable

process

public void process(SpeechContext context,
                    ByteBuffer frame)

processes a frame of audio.

Specified by:

process in interface SpeechProcessor

Parameters:

context - the current speech context

frame - the audio frame to detect