function mic(options) {
options = options || {};
var that = {};
var endian = options.endian || 'little';
var bitwidth = options.bitwidth || '16';
var encoding = options.encoding || 'signed-integer';
var rate = options.rate || '16000';
var channels = options.channels || '1';
var device = options.device || 'plughw:1,0';
var exitOnSilence = options.exitOnSilence || 0;
var debug = options.debug || false;
var format, formatEndian, formatEncoding;
var audioProcess = null;
var infoStream = new PassThrough;
var audioStream = new IsSilence({debug: debug});
var audioProcessOptions = {
stdio: ['ignore', 'pipe', 'ignore']
};
if(debug) {
audioProcessOptions.stdio[2] = 'pipe';
}
// Setup format variable for arecord call
if(endian === 'big') {
formatEndian = 'BE';
} else {
formatEndian = 'LE';
}
if(encoding === 'unsigned-integer') {
formatEncoding = 'U';
} else {
formatEncoding = 'S';
}
format = formatEncoding + bitwidth + '_' + formatEndian;
audioStream.setNumSilenceFramesExitThresh(parseInt(exitOnSilence, 10));
that.start = function start() {
if(audioProcess === null) {
audioProcess = isMac
? spawn('rec', ['-b', bitwidth, '--endian', endian, '-c', channels, '-r', rate, '-e', encoding, '-t', 'raw', '-'], audioProcessOptions
)
: spawn('arecord', ['-c', channels, '-r', rate, '-f', format, '-D', device], audioProcessOptions);
audioProcess.on('exit', function(code, sig) {
if(code != null && sig === null) {
audioStream.emit('audioProcessExitComplete');
if(debug) console.log("recording audioProcess has exited with code = %d", code);
}
});
audioProcess.stdout.pipe(audioStream);
if(debug) {
audioProcess.stderr.pipe(infoStream);
}
audioStream.emit('startComplete');
} else {
if(debug) {
throw new Error("Duplicate calls to start(): Microphone already started!");
}
}
};
that.stop = function stop() {
if(audioProcess != null) {
audioProcess.kill('SIGTERM');
audioProcess = null;
audioStream.emit('stopComplete');
if(debug) console.log("Microhphone stopped");
}
};
that.pause = function pause() {
if(audioProcess != null) {
audioProcess.kill('SIGSTOP');
audioStream.pause();
audioStream.emit('pauseComplete');
if(debug) console.log("Microphone paused");
}
};
that.resume = function resume() {
if(audioProcess != null) {
audioProcess.kill('SIGCONT');
audioStream.resume();
audioStream.emit('resumeComplete');
if(debug) console.log("Microphone resumed");
}
}
that.getAudioStream = function getAudioStream() {
return audioStream;
}
if(debug) {
infoStream.on('data', function(data) {
console.log("Received Info: " + data);
});
infoStream.on('error', function(error) {
console.log("Error in Info Stream: " + error);
});
}
return that;
}n/a
function IsSilence(options) {
var that = this;
if (options && options.debug) {
that.debug = options.debug;
delete options.debug;
}
Transform.call(that, options);
var consecSilenceCount = 0;
var numSilenceFramesExitThresh = 0;
that.getNumSilenceFramesExitThresh = function getNumSilenceFramesExitThresh() {
return numSilenceFramesExitThresh;
};
that.getConsecSilenceCount = function getConsecSilenceCount() {
return consecSilenceCount;
};
that.setNumSilenceFramesExitThresh = function setNumSilenceFramesExitThresh(numFrames) {
numSilenceFramesExitThresh = numFrames;
return;
};
that.incrConsecSilenceCount = function incrConsecSilenceCount() {
consecSilenceCount++;
return consecSilenceCount;
};
that.resetConsecSilenceCount = function resetConsecSilenceCount() {
consecSilenceCount = 0;
return;
};
}n/a
function IsSilence(options) {
var that = this;
if (options && options.debug) {
that.debug = options.debug;
delete options.debug;
}
Transform.call(that, options);
var consecSilenceCount = 0;
var numSilenceFramesExitThresh = 0;
that.getNumSilenceFramesExitThresh = function getNumSilenceFramesExitThresh() {
return numSilenceFramesExitThresh;
};
that.getConsecSilenceCount = function getConsecSilenceCount() {
return consecSilenceCount;
};
that.setNumSilenceFramesExitThresh = function setNumSilenceFramesExitThresh(numFrames) {
numSilenceFramesExitThresh = numFrames;
return;
};
that.incrConsecSilenceCount = function incrConsecSilenceCount() {
consecSilenceCount++;
return consecSilenceCount;
};
that.resetConsecSilenceCount = function resetConsecSilenceCount() {
consecSilenceCount = 0;
return;
};
}n/a
function Transform(options) {
if (!(this instanceof Transform))
return new Transform(options);
Duplex.call(this, options);
this._transformState = new TransformState(this);
var stream = this;
// start out asking for a readable event once data is transformed.
this._readableState.needReadable = true;
// we have implemented the _read method, and done the other things
// that Readable wants before the first _read call, so unset the
// sync guard flag.
this._readableState.sync = false;
if (options) {
if (typeof options.transform === 'function')
this._transform = options.transform;
if (typeof options.flush === 'function')
this._flush = options.flush;
}
// When the writable side finishes, then flush out anything remaining.
this.once('prefinish', function() {
if (typeof this._flush === 'function')
this._flush(function(er) {
done(stream, er);
});
else
done(stream);
});
}n/a
_transform = function (chunk, encoding, callback) {
var i;
var speechSample;
var silenceLength = 0;
var self = this;
var debug = self.debug;
var consecutiveSilence = self.getConsecSilenceCount();
var numSilenceFramesExitThresh = self.getNumSilenceFramesExitThresh();
var incrementConsecSilence = self.incrConsecSilenceCount;
var resetConsecSilence = self.resetConsecSilenceCount;
if(numSilenceFramesExitThresh) {
for(i=0; i<chunk.length; i=i+2) {
if(chunk[i+1] > 128) {
speechSample = (chunk[i+1] - 256) * 256;
} else {
speechSample = chunk[i+1] * 256;
}
speechSample += chunk[i];
if(Math.abs(speechSample) > 2000) {
if (debug) {
console.log("Found speech block");
}
resetConsecSilence();
break;
} else {
silenceLength++;
}
}
if(silenceLength == chunk.length/2) {
consecutiveSilence = incrementConsecSilence();
if (debug) {
console.log("Found silence block: %d of %d", consecutiveSilence, numSilenceFramesExitThresh);
}
//emit 'silence' only once each time the threshold condition is met
if( consecutiveSilence === numSilenceFramesExitThresh) {
self.emit('silence');
}
}
}
this.push(chunk);
callback();
}n/a