Change decoder API

native_client/BUILD

@@ -181,21 +181,6 @@ genrule(
     cmd = "dsymutil $(location :libdeepspeech.so) -o $@"
 )
 
-cc_binary(
-    name = "generate_trie",
-    srcs = [
-        "alphabet.h",
-        "generate_trie.cpp",
-    ],
-    copts = ["-std=c++11"],
-    linkopts = [
-        "-lm",
-        "-ldl",
-        "-pthread",
-    ],
-    deps = [":decoder"],
-)
-
 cc_binary(
     name = "trie_load",
     srcs = [

native_client/ctcdecode/scorer.cpp

@@ -24,39 +24,29 @@
 
 #include "decoder_utils.h"
 
-using namespace lm::ngram;
-
 static const int32_t MAGIC = 'TRIE';
 static const int32_t FILE_VERSION = 6;
 
 int
-Scorer::init(double alpha,
-             double beta,
-             const std::string& lm_path,
-             const std::string& trie_path,
+Scorer::init(const std::string& lm_path,
              const Alphabet& alphabet)
 {
-  reset_params(alpha, beta);
   alphabet_ = alphabet;
   setup_char_map();
-  load_lm(lm_path, trie_path);
+  load_lm(lm_path);
   return 0;
 }
 
 int
-Scorer::init(double alpha,
-             double beta,
-             const std::string& lm_path,
-             const std::string& trie_path,
+Scorer::init(const std::string& lm_path,
              const std::string& alphabet_config_path)
 {
-  reset_params(alpha, beta);
   int err = alphabet_.init(alphabet_config_path.c_str());
   if (err != 0) {
     return err;
   }
   setup_char_map();
-  load_lm(lm_path, trie_path);
+  load_lm(lm_path);
   return 0;
 }
 
@@ -82,7 +72,7 @@ void Scorer::setup_char_map()
   }
 }
 
-void Scorer::load_lm(const std::string& lm_path, const std::string& trie_path)
+void Scorer::load_lm(const std::string& lm_path)
 {
   // load language model
   const char* filename = lm_path.c_str();

native_client/ctcdecode/scorer.h

@@ -50,16 +50,10 @@ public:
   Scorer(const Scorer&) = delete;
   Scorer& operator=(const Scorer&) = delete;
 
-  int init(double alpha,
-           double beta,
-           const std::string &lm_path,
-           const std::string &trie_path,
+  int init(const std::string &lm_path,
            const Alphabet &alphabet);
 
-  int init(double alpha,
-           double beta,
-           const std::string &lm_path,
-           const std::string &trie_path,
+  int init(const std::string &lm_path,
            const std::string &alphabet_config_path);
 
   double get_log_cond_prob(const std::vector<std::string> &words,
@@ -104,7 +98,7 @@ public:
   void fill_dictionary(const std::vector<std::string> &vocabulary);
 
   // load language model from given path
-  void load_lm(const std::string &lm_path, const std::string &trie_path);
+  void load_lm(const std::string &lm_path);
 
   // language model weight
   double alpha = 0.;

native_client/deepspeech.cc

@@ -304,23 +304,38 @@ DS_FreeModel(ModelState* ctx)
 }
 
 int
-DS_EnableDecoderWithLM(ModelState* aCtx,
-                       const char* aLMPath,
-                       const char* aTriePath,
-                       float aLMAlpha,
-                       float aLMBeta)
+DS_EnableExternalScorer(ModelState* aCtx,
+                        const char* aScorerPath)
 {
   aCtx->scorer_.reset(new Scorer());
-  int err = aCtx->scorer_->init(aLMAlpha, aLMBeta,
-                                aLMPath ? aLMPath : "",
-                                aTriePath ? aTriePath : "",
-                                aCtx->alphabet_);
+  int err = aCtx->scorer_->init(aScorerPath, aCtx->alphabet_);
   if (err != 0) {
     return DS_ERR_INVALID_LM;
   }
   return DS_ERR_OK;
 }
 
+int
+DS_DisableExternalScorer(ModelState* aCtx)
+{
+  if (aCtx->scorer_) {
+    aCtx->scorer_.reset(nullptr);
+    return DS_ERR_OK;
+  }
+  return DS_ERR_SCORER_NOT_ENABLED;
+}
+
+int DS_SetScorerAlphaBeta(ModelState* aCtx,
+                          float aAlpha,
+                          float aBeta)
+{
+  if (aCtx->scorer_) {
+    aCtx->scorer_->reset_params(aAlpha, aBeta);
+    return DS_ERR_OK;
+  }
+  return DS_ERR_SCORER_NOT_ENABLED;
+}
+
 int
 DS_CreateStream(ModelState* aCtx,
                 StreamingState** retval)

native_client/deepspeech.h

@@ -61,6 +61,7 @@ enum DeepSpeech_Error_Codes
     DS_ERR_INVALID_SHAPE      = 0x2001,
     DS_ERR_INVALID_LM         = 0x2002,
     DS_ERR_MODEL_INCOMPATIBLE = 0x2003,
+    DS_ERR_SCORER_NOT_ENABLED = 0x2004,
 
     // Runtime failures
     DS_ERR_FAIL_INIT_MMAP     = 0x3000,
@@ -106,25 +107,40 @@ DEEPSPEECH_EXPORT
 void DS_FreeModel(ModelState* ctx);
 
 /**
- * @brief Enable decoding using beam scoring with a KenLM language model.
+ * @brief Enable decoding using an external scorer.
  *
  * @param aCtx The ModelState pointer for the model being changed.
- * @param aLMPath The path to the language model binary file.
- * @param aTriePath The path to the trie file build from the same vocabu-
- *                  lary as the language model binary.
- * @param aLMAlpha The alpha hyperparameter of the CTC decoder. Language Model
-                   weight.
- * @param aLMBeta The beta hyperparameter of the CTC decoder. Word insertion
-                  weight.
+ * @param aScorerPath The path to the external scorer file.
  *
  * @return Zero on success, non-zero on failure (invalid arguments).
  */
 DEEPSPEECH_EXPORT
-int DS_EnableDecoderWithLM(ModelState* aCtx,
-                           const char* aLMPath,
-                           const char* aTriePath,
-                           float aLMAlpha,
-                           float aLMBeta);
+int DS_EnableExternalScorer(ModelState* aCtx,
+                            const char* aScorerPath);
+
+/**
+ * @brief Disable decoding using an external scorer.
+ *
+ * @param aCtx The ModelState pointer for the model being changed.
+ *
+ * @return Zero on success, non-zero on failure.
+ */
+DEEPSPEECH_EXPORT
+int DS_DisableExternalScorer(ModelState* aCtx);
+
+/**
+ * @brief Set hyperparameters alpha and beta of a KenLM external scorer.
+ *
+ * @param aCtx The ModelState pointer for the model being changed.
+ * @param aAlpha The alpha hyperparameter of the decoder. Language model weight.
+ * @param aLMBeta The beta hyperparameter of the decoder. Word insertion weight.
+ *
+ * @return Zero on success, non-zero on failure.
+ */
+DEEPSPEECH_EXPORT
+int DS_SetScorerAlphaBeta(ModelState* aCtx,
+                          float aAlpha,
+                          float aBeta);
 
 /**
  * @brief Use the DeepSpeech model to perform Speech-To-Text.

native_client/generate_trie.cpp

@@ -1,32 +0,0 @@
-#include <algorithm>
-#include <iostream>
-#include <string>
-
-#include "ctcdecode/scorer.h"
-#include "alphabet.h"
-
-using namespace std;
-
-int generate_trie(const char* alphabet_path, const char* kenlm_path, const char* trie_path) {
-  Alphabet alphabet;
-  int err = alphabet.init(alphabet_path);
-  if (err != 0) {
-    return err;
-  }
-  Scorer scorer;
-  err = scorer.init(0.0, 0.0, kenlm_path, "", alphabet);
-  if (err != 0) {
-    return err;
-  }
-  scorer.save_dictionary(trie_path);
-  return 0;
-}
-
-int main(int argc, char** argv) {
-  if (argc != 4) {
-    std::cerr << "Usage: " << argv[0] << " <alphabet> <lm_model> <trie_path>" << std::endl;
-    return -1;
-  }
-
-  return generate_trie(argv[1], argv[2], argv[3]);
-}

native_client/trie_load.cc

@@ -27,9 +27,9 @@ int main(int argc, char** argv)
     return err;
   }
   Scorer scorer;
-
+  err = scorer.init(kenlm_path, alphabet);
 #ifndef DEBUG
-  return scorer.init(0.0, 0.0, kenlm_path, trie_path, alphabet);
+  return err;
 #else
   // Print some info about the FST
   using FstType = fst::ConstFst<fst::StdArc>;
@@ -60,7 +60,6 @@ int main(int argc, char** argv)
   // for (int i = 1; i < 10; ++i) {
   //   print_states_from(i);
   // }
-#endif // DEBUG
-
   return 0;
+#endif // DEBUG
 }