googleSpeech.js

const speech = require('@google-cloud/speech');
const fs = require('fs');
const logger = console;

class GoogleSpeech
{
	constructor()
	{
		logger.debug('constructor()');

		// Google Speech client.
		this._client = new speech.SpeechClient();

		// Google Speech configuration request.
		this._request =
		{
			config : {
				encoding              : 'LINEAR16',
				sampleRateHertz       : 8000,
				enableWordTimeOffsets : true,
				languageCode          : 'fr-FR'
			},
			// 'true' to perform continuous recognition even if the user pauses speaking.
			singleUtterance : false,
			// 'true' to enable tentative hypoteses.
			interimResults  : true
		};

		// Plain audio readable stream.
		this._audioStream = null;
		this._time = 0;
	}

	/**
	 * @param {Readable} audioStream
	 */
	start(filename)
	{
		logger.debug('start()');
		//this._audioStream = fs.createReadStream(filename, { highWaterMark: sampleRateHertz*2*0.2 });
		this._audioStream = fs.createReadStream(filename, { highWaterMark: 8000*2*0.2 });
		this._audioStream
		.on('data', (chunk) => {
				this._audioStream.pause();
				setTimeout(() => {
					this._time += 200;

					if (this._time % 1000 === 0) {
						console.log(`[INFO] elapsed time : ${this._time/1000} sec`);
					}
					this._audioStream.resume();
					}, 200);
		})

		this._start();
	}

	stop()
	{
		logger.debug('stop()');
	}

	_start()
	{
		logger.debug('_start()');

		try
		{
			// Create a writable stream to which pipe the plain audio.
			this._recognizeStream = this._client.streamingRecognize(this._request);
		}
		catch (error)
		{
			logger.error('streamingRecognize() error: [%s]', error.message);

			return;
		}

		this._recognizeStream
			.on('error', (error) =>
			{
				logger.error('streamingRecognize() "error" event [%s]', error.message);
				//this._audioStream.pause();
				//this._audioStream.unpipe(this._recognizeStream);
			})
			.on('data', (data) =>
			{
				if (data.error) {
					logger.error('streamingRecognize() "data" event error [%s]', data.error);
					this._audioStream.unpipe(this._recognizeStream);
					this._audioStream.pause();
				} else
					logger.debug(data.results[0].alternatives[0].transcript);
			})
			.on('unpipe', () =>
			{
				delete this._recognizeStream;

				this._start();
			});

		// Pipe the audio stream into the Speech API.
		console.log('this._audioStream :', this._audioStream);
		this._audioStream.pipe(this._recognizeStream);
	}
}

let gSpeech = new GoogleSpeech();
gSpeech.start('test-recording.wav');