Adapt JavaScript bindings to new API

native_client/javascript/client.js

@@ -42,12 +42,11 @@ function totalTime(hrtimeValue) {
   return (hrtimeValue[0] + hrtimeValue[1] / 1000000000).toPrecision(4);
 }
 
-function metadataToString(metadata) {
+function candidateTranscriptToString(transcript) {
   var retval = ""
-  for (var i = 0; i < metadata.num_items; ++i) {
-    retval += metadata.items[i].character;
+  for (var i = 0; i < transcript.tokens.length; ++i) {
+    retval += transcript.tokens[i].text;
   }
-  Ds.FreeMetadata(metadata);
   return retval;
 }
 
@@ -117,7 +116,9 @@ audioStream.on('finish', () => {
   const audioLength = (audioBuffer.length / 2) * (1 / desired_sample_rate);
 
   if (args['extended']) {
-    console.log(metadataToString(model.sttWithMetadata(audioBuffer)));
+    let metadata = model.sttWithMetadata(audioBuffer, 1);
+    console.log(candidateTranscriptToString(metadata.transcripts[0]));
+    Ds.FreeMetadata(metadata);
   } else {
     console.log(model.stt(audioBuffer));
   }

native_client/javascript/deepspeech.i

@@ -47,8 +47,8 @@ using namespace node;
 %typemap(argout) ModelState **retval {
   $result = SWIGV8_ARRAY_NEW();
   SWIGV8_AppendOutput($result, SWIG_From_int(result));
-  // owned by SWIG, ModelState destructor gets called when the JavaScript object is finalized (see below)
-  %append_output(SWIG_NewPointerObj(%as_voidptr(*$1), $*1_descriptor, SWIG_POINTER_OWN));
+  // owned by the application. NodeJS does not guarantee the finalizer will be called so applications must call FreeMetadata themselves.
+  %append_output(SWIG_NewPointerObj(%as_voidptr(*$1), $*1_descriptor, 0));
 }
 
 
@@ -68,27 +68,33 @@ using namespace node;
 %nodefaultctor ModelState;
 %nodefaultdtor ModelState;
 
-%typemap(out) MetadataItem* %{
+%typemap(out) TokenMetadata* %{
   $result = SWIGV8_ARRAY_NEW();
-  for (int i = 0; i < arg1->num_items; ++i) {
-    SWIGV8_AppendOutput($result, SWIG_NewPointerObj(SWIG_as_voidptr(&result[i]), SWIGTYPE_p_MetadataItem, SWIG_POINTER_OWN));
+  for (int i = 0; i < arg1->num_tokens; ++i) {
+    SWIGV8_AppendOutput($result, SWIG_NewPointerObj(SWIG_as_voidptr(&result[i]), SWIGTYPE_p_TokenMetadata, 0));
   }
 %}
 
-%nodefaultdtor Metadata;
-%nodefaultctor Metadata;
-%nodefaultctor MetadataItem;
-%nodefaultdtor MetadataItem;
-
-%extend struct Metadata {
-  ~Metadata() {
-    DS_FreeMetadata($self);
+%typemap(out) CandidateTranscript* %{
+  $result = SWIGV8_ARRAY_NEW();
+  for (int i = 0; i < arg1->num_transcripts; ++i) {
+    SWIGV8_AppendOutput($result, SWIG_NewPointerObj(SWIG_as_voidptr(&result[i]), SWIGTYPE_p_CandidateTranscript, 0));
   }
-}
+%}
 
-%extend struct MetadataItem {
-  ~MetadataItem() { }
-}
+%ignore Metadata::num_transcripts;
+%ignore CandidateTranscript::num_tokens;
+
+%immutable Metadata::transcripts;
+%immutable CandidateTranscripts::tokens;
+%immutable TokenMetadata::text;
+
+%nodefaultctor Metadata;
+%nodefaultdtor Metadata;
+%nodefaultctor CandidateTranscript;
+%nodefaultdtor CandidateTranscript;
+%nodefaultctor TokenMetadata;
+%nodefaultdtor TokenMetadata;
 
 %rename ("%(strip:[DS_])s") "";
 

native_client/javascript/index.js

@@ -122,8 +122,9 @@ Model.prototype.stt = function(aBuffer) {
  *
  * @return {object} Outputs a :js:func:`Metadata` struct of individual letters along with their timing information. The user is responsible for freeing Metadata by calling :js:func:`FreeMetadata`. Returns undefined on error.
  */
-Model.prototype.sttWithMetadata = function(aBuffer) {
-    return binding.SpeechToTextWithMetadata(this._impl, aBuffer);
+Model.prototype.sttWithMetadata = function(aBuffer, aNumResults) {
+    aNumResults = aNumResults || 1;
+    return binding.SpeechToTextWithMetadata(this._impl, aBuffer, aNumResults);
 }
 
 /**
@@ -171,6 +172,16 @@ Stream.prototype.intermediateDecode = function() {
     return binding.IntermediateDecode(this._impl);
 }
 
+/**
+ * Compute the intermediate decoding of an ongoing streaming inference.
+ *
+ * @return {string} The STT intermediate result.
+ */
+Stream.prototype.intermediateDecodeWithMetadata = function(aNumResults) {
+    aNumResults = aNumResults || 1;
+    return binding.IntermediateDecode(this._impl, aNumResults);
+}
+
 /**
  * Signal the end of an audio signal to an ongoing streaming inference, returns the STT result over the whole audio signal.
  *
@@ -191,8 +202,9 @@ Stream.prototype.finishStream = function() {
  *
  * This method will free the stream, it must not be used after this method is called.
  */
-Stream.prototype.finishStreamWithMetadata = function() {
-    result = binding.FinishStreamWithMetadata(this._impl);
+Stream.prototype.finishStreamWithMetadata = function(aNumResults) {
+    aNumResults = aNumResults || 1;
+    result = binding.FinishStreamWithMetadata(this._impl, aNumResults);
     this._impl = null;
     return result;
 }
@@ -236,35 +248,58 @@ function Version() {
 }
 
 
-//// Metadata and MetadataItem are here only for documentation purposes
+//// Metadata, CandidateTranscript and TokenMetadata are here only for documentation purposes
 
 /**
  * @class
  * 
  * Stores each individual character, along with its timing information
  */
-function MetadataItem() {}
+function TokenMetadata() {}
 
 /** 
  * The character generated for transcription
  *
  * @return {string} The character generated
  */
-MetadataItem.prototype.character = function() {}
+TokenMetadata.prototype.text = function() {}
 
 /**
  * Position of the character in units of 20ms
  *
  * @return {int} The position of the character
  */
-MetadataItem.prototype.timestep = function() {};
+TokenMetadata.prototype.timestep = function() {};
 
 /**
  * Position of the character in seconds
  *
  * @return {float} The position of the character
  */
-MetadataItem.prototype.start_time = function() {};
+TokenMetadata.prototype.start_time = function() {};
+
+/**
+ * @class
+ *
+ * Stores the entire CTC output as an array of character metadata objects
+ */
+function CandidateTranscript () {}
+
+/**
+ * List of items
+ *
+ * @return {array} List of :js:func:`TokenMetadata`
+ */
+CandidateTranscript.prototype.items = function() {}
+
+/**
+ * Approximated confidence value for this transcription. This is roughly the
+ * sum of the acoustic model logit values for each timestep/character that
+ * contributed to the creation of this transcription.
+ *
+ * @return {float} Confidence value
+ */
+CandidateTranscript.prototype.confidence = function() {}
 
 /**
  * @class
@@ -276,30 +311,16 @@ function Metadata () {}
 /**
  * List of items
  *
- * @return {array} List of :js:func:`MetadataItem`
+ * @return {array} List of :js:func:`CandidateTranscript` objects
  */
-Metadata.prototype.items = function() {}
+Metadata.prototype.transcripts = function() {}
 
-/**
- * Size of the list of items
- *
- * @return {int} Number of items
- */
-Metadata.prototype.num_items = function() {}
-
-/**
- * Approximated confidence value for this transcription. This is roughly the
- * sum of the acoustic model logit values for each timestep/character that
- * contributed to the creation of this transcription.
- *
- * @return {float} Confidence value
- */
-Metadata.prototype.confidence = function() {}
 
 module.exports = {
     Model: Model,
     Metadata: Metadata,
-    MetadataItem: MetadataItem,
+    CandidateTranscript: CandidateTranscript,
+    TokenMetadata: TokenMetadata,
     Version: Version,
     FreeModel: FreeModel,
     FreeStream: FreeStream,