[speech-to-text] Add recognize options

services/speech_to_text/v1.js

@@ -391,13 +391,7 @@ function RecognizeStream(options){
 
   var queryParams = extend({model: 'en-US_BroadbandModel'}, pick(options, ['model', 'X-Watson-Learning-Opt-Out', 'watson-token']));
 
-  var openingMessage = extend({
-    // todo: confirm the mixed underscores/hyphens and/or get it fixed
-    action: 'start',
-    'content-type': 'audio/wav', // todo: try to determine content-type from the file extension if available
-    'continuous': false,
-    'interim_results': true
-  }, pick(options, [PARAMS_ALLOWED]));
+  var openingMessage = pick(options, PARAMS_ALLOWED);
 
   var closingMessage = {action: 'stop'};
 
@@ -471,8 +465,8 @@ function RecognizeStream(options){
         }
       } else if (data.results) {
         self.emit('results', data);
-        // note: currently there is always exactly 1 entry in the results array. However, this may change in the future.
-        if(data.results[0].final && data.results[0].alternatives) {
+        // note: usually exactly 1 entry in results. Edge case: zero entries. E.g., silent audio sent from pipeline
+        if(data.results[0] && data.results[0].final && data.results[0].alternatives) {
           self.push(data.results[0].alternatives[0].transcript, 'utf8'); // this is the "data" event that can be easily piped to other streams
         }
       } else {