nodejs fix: mic example not working alphacep#1203

nodejs/demo/test_microphone.js

@@ -1,46 +1,61 @@
-var vosk = require('..')
-
-const fs = require("fs");
-var mic = require("mic");
-
-MODEL_PATH = "model"
-SAMPLE_RATE = 16000
+const vosk = require('..');
+const fs = require('fs');
+const { spawn } = require('child_process');
+const { platform } = require('os');
+
+const MODEL_PATH = 'model';
+const SAMPLE_RATE = 16000;
+const soxInputPlatformDic = {
+  win32: 'waveaudio',
+  linux: 'pulseaudio',
+  darwin: 'coreaudio',
+};
 
 if (!fs.existsSync(MODEL_PATH)) {
-    console.log("Please download the model from https://alphacephei.com/vosk/models and unpack as " + MODEL_PATH + " in the current folder.")
-    process.exit()
+  console.log(
+    'Please download the model from https://alphacephei.com/vosk/models and unpack as ' +
+      MODEL_PATH +
+      ' in the current folder.',
+  );
+  process.exit();
 }
 
-vosk.setLogLevel(0);
+vosk.setLogLevel(1);
 const model = new vosk.Model(MODEL_PATH);
-const rec = new vosk.Recognizer({model: model, sampleRate: SAMPLE_RATE});
-
-var micInstance = mic({
-    rate: String(SAMPLE_RATE),
-    channels: '1',
-    debug: false,
-    device: 'default',    
+const rec = new vosk.Recognizer({ model: model, sampleRate: SAMPLE_RATE });
+
+// Install Sox before using this example: https://sourceforge.net/projects/sox/files/sox/
+const soxProcess = spawn(`sox`, [
+  '-b',
+  '16',
+  '--endian',
+  'little',
+  '-c',
+  '1',
+  '-r',
+  '16k',
+  '-e',
+  'signed-integer',
+  '-t',
+  soxInputPlatformDic[platform],
+  'default',
+  '-t',
+  'wav',
+  '-',
+]);
+
+// Pass audio (data) into the Vosk API
+soxProcess.stdout.on('data', data => {
+  if (rec.acceptWaveform(data)) console.log(rec.result());
+  else console.log(rec.partialResult());
 });
 
-var micInputStream = micInstance.getAudioStream();
-
-micInputStream.on('data', data => {
-    if (rec.acceptWaveform(data))
-        console.log(rec.result());
-    else
-        console.log(rec.partialResult());
+// Handle errors of Sox instance
+soxProcess.on('error', error => {
+  console.log('Error executing Sox: ', error.message);
 });
 
-micInputStream.on('audioProcessExitComplete', function() {
-    console.log("Cleaning up");
-    console.log(rec.finalResult());
-    rec.free();
-    model.free();
+process.on('SIGINT', function () {
+  console.log('\nStopping');
+  soxProcess.kill('SIGTERM');
 });
-
-process.on('SIGINT', function() {
-    console.log("\nStopping");
-    micInstance.stop();
-});
-
-micInstance.start();