pvcobrademo 1.0.4

Cobra voice activity detection (VAD) engine demos.

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
• Runs on Linux (x86_64), Mac (x86_64), Windows (x86_64), Raspberry Pi (all variants), NVIDIA Jetson (Nano), and BeagleBone.

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.