IBM Watson Speech-to-Text JavaScript SDK: how to get messages?

Question

I'm seeing the word transcriptions, either in the browser or in the console, but I'm not seeing the messages such as {'state': 'listening'}. More importantly, I'm not seeing the results such as {"results": [{"alternatives": [{"transcript": "name the mayflower "}],"final": true}],"result_index": 0}.

I read the RecognizeStream documentation and tried this code:

stream.on('message', function(message) {
    console.log(message);
  });

but that doesn't work. I tried object_mode in both true and false but the output was the same.

Here's the full code that I'm using:

document.querySelector('#button').onclick = function () {

  var stream = WatsonSpeech.SpeechToText.recognizeMicrophone({
    token: token,
    model: 'en-US_BroadbandModel',
    keywords: ["Colorado"],
    keywords_threshold: 0.50,
    word_confidence: true,
    // outputElement: '#output' // send text to browser instead of console
    object_mode: false
  });

  stream.setEncoding('utf8'); // get text instead of Buffers for on data events

  stream.on('data', function(data) { // send text to console instead of browser
    console.log(data);
  });

  stream.on('error', function(err) {
    console.log(err);
  });

  document.querySelector('#stop').onclick = function() {
    stream.stop();
  };
};

Answer 1

The recognizeMicrophone() method is a helper that chains together a number of streams. The message event is fired on one of the streams in the middle. But, you can get access to that one at stream.recognizeStream - it's always attached to the last one in the chain in order to support cases like this.

So, in your code, it should look something like this:

stream.recognizeStream.on('message', function(frame, data) {
  console.log('message', frame, data)
});

However, that is mainly there for debugging. The results JSON should be emitted on the data event, if you set objectMode: true and don't call stream.setEncoding('utf8');.

(This is somewhat different from Watson Node.js SDK, if you're familiar with it's behavior. There are plans to unify the two, but never enough time...)