Cobra Voice Activity Detection engine

Made in Vancouver, Canada by Picovoice

This package contains demos and commandline utilities for processing real-time audio (i.e. microphone) and audio files using Cobra voice activity detection engine.

Cobra

Cobra is a highly accurate and lightweight voice activity detection (VAD) engine.

Compatibility

• Python 3.9+
• Runs on Linux (x86_64), macOS (x86_64 and arm64), Windows (x86_64, arm64), and Raspberry Pi (3, 4, 5).

AccessKey

Cobra requires a valid Picovoice AccessKey at initialization. AccessKey acts as your credentials when using Cobra SDKs. You can get your AccessKey for free. Make sure to keep your AccessKey secret. Signup or Login to Picovoice Console to get your AccessKey.

Installation

sudo pip3 install pvcobrademo

Usage

Microphone Demo

The Microphone demo opens an audio stream from a microphone and detects voice activities. The following opens the default microphone:

cobra_demo_mic --access_key {AccessKey}

where {AccessKey} is an AccessKey which should be obtained from Picovoice Console. It is possible that the default audio input device recognized by pvrecorder is not the one being used. There are a couple of debugging facilities baked into the demo application to solve this. First, type the following into the console:

cobra_demo_mic --show_audio_devices

It provides information about various audio input devices on the box. On a Linux box, this is the console output:

'index': '0', 'name': 'HDA Intel PCH: ALC892 Analog (hw:0,0)', 'defaultSampleRate': '44100.0', 'maxInputChannels': '2'
'index': '1', 'name': 'HDA Intel PCH: ALC892 Alt Analog (hw:0,2)', 'defaultSampleRate': '44100.0', 'maxInputChannels': '2'
'index': '2', 'name': 'HDA NVidia: HDMI 0 (hw:1,3)', 'defaultSampleRate': '44100.0', 'maxInputChannels': '0'
'index': '3', 'name': 'HDA NVidia: HDMI 1 (hw:1,7)', 'defaultSampleRate': '44100.0', 'maxInputChannels': '0'
'index': '4', 'name': 'HDA NVidia: HDMI 2 (hw:1,8)', 'defaultSampleRate': '44100.0', 'maxInputChannels': '0'
'index': '5', 'name': 'HDA NVidia: HDMI 3 (hw:1,9)', 'defaultSampleRate': '44100.0', 'maxInputChannels': '0'
'index': '6', 'name': 'HDA NVidia: HDMI 0 (hw:2,3)', 'defaultSampleRate': '44100.0', 'maxInputChannels': '0'
'index': '7', 'name': 'HDA NVidia: HDMI 1 (hw:2,7)', 'defaultSampleRate': '44100.0', 'maxInputChannels': '0'
'index': '8', 'name': 'HDA NVidia: HDMI 2 (hw:2,8)', 'defaultSampleRate': '44100.0', 'maxInputChannels': '0'
'index': '9', 'name': 'HDA NVidia: HDMI 3 (hw:2,9)', 'defaultSampleRate': '44100.0', 'maxInputChannels': '0'
'index': '10', 'name': 'Logitech USB Headset: Audio (hw:3,0)', 'defaultSampleRate': '44100.0', 'maxInputChannels': '1'
'index': '11', 'name': 'sysdefault', 'defaultSampleRate': '48000.0', 'maxInputChannels': '128'
'index': '12', 'name': 'front', 'defaultSampleRate': '44100.0', 'maxInputChannels': '0'
'index': '13', 'name': 'surround21', 'defaultSampleRate': '44100.0', 'maxInputChannels': '0'
'index': '14', 'name': 'surround40', 'defaultSampleRate': '44100.0', 'maxInputChannels': '0'
'index': '15', 'name': 'surround41', 'defaultSampleRate': '44100.0', 'maxInputChannels': '0'
'index': '16', 'name': 'surround50', 'defaultSampleRate': '44100.0', 'maxInputChannels': '0'
'index': '17', 'name': 'surround51', 'defaultSampleRate': '44100.0', 'maxInputChannels': '0'
'index': '18', 'name': 'surround71', 'defaultSampleRate': '44100.0', 'maxInputChannels': '0'
'index': '19', 'name': 'pulse', 'defaultSampleRate': '44100.0', 'maxInputChannels': '32'
'index': '20', 'name': 'dmix', 'defaultSampleRate': '48000.0', 'maxInputChannels': '0'
'index': '21', 'name': 'default', 'defaultSampleRate': '44100.0', 'maxInputChannels': '32'

It can be seen that the last device (index 21) is considered default. But on this machine, a headset is being used as the input device which has an index of 10. After finding the correct index the demo application can be invoked as below:

cobra_demo_mic --access_key {AccessKey} --audio_device_index 10

If the problem persists we suggest storing the recorded audio into a file for inspection. This can be achieved by:

cobra_demo_mic --access_key {AccessKey} --audio_device_index 10 --output_path ~/test.wav

If after listening to stored file there is no apparent problem detected please open an issue.

File Demo

It allows testing Cobra on a corpus of audio files. The demo is mainly useful for quantitative performance benchmarking. It accepts 16kHz audio files. Cobra processes a single-channel audio stream if a stereo file is provided it only processes the first (left) channel. The following processes a file looking for voice activities:

cobra_demo_file --access_key {AccessKey} --input_audio_path ${AUDIO_PATH}

where {AccessKey} is an AccessKey which should be obtained from Picovoice Console. The threshold of the engine can be tuned using the threshold input argument:

cobra_demo_file --access_key {AccessKey} --input_audio_path ${AUDIO_PATH} \
 --threshold 0.9

Threshold is a floating point number within [0, 1]. A higher threshold reduces the miss rate at the cost of increased false alarm rate.