[runtime] Configurable blank token idx (#2366)

* Pass in blank id * Fix * ctc endpointing blank id --------- Co-authored-by: hzhou245 <hzhou245@bloomberg.net>
wenet-e2e · Feb 26, 2024 · 89ef2e7 · 89ef2e7
1 parent fbbecfd
commit 89ef2e7
Show file tree

Hide file tree

Showing 4 changed files with 11 additions and 4 deletions.
diff --git a/runtime/core/decoder/ctc_wfst_beam_search.cc b/runtime/core/decoder/ctc_wfst_beam_search.cc
@@ -77,7 +77,7 @@ void CtcWfstBeamSearch::Search(const std::vector<std::vector<float>>& logp) {
   }
   // Every time we get the log posterior, we decode it all before return
   for (int i = 0; i < logp.size(); i++) {
-    float blank_score = std::exp(logp[i][0]);
+    float blank_score = std::exp(logp[i][opts_.blank]);
     if (blank_score > opts_.blank_skip_thresh * opts_.blank_scale) {
       VLOG(3) << "skipping frame " << num_frames_ << " score " << blank_score;
       is_last_frame_blank_ = true;
@@ -88,7 +88,8 @@ void CtcWfstBeamSearch::Search(const std::vector<std::vector<float>>& logp) {
           std::max_element(logp[i].begin(), logp[i].end()) - logp[i].begin();
       // Optional, adding one blank frame if we has skipped it in two same
       // symbols
-      if (cur_best != 0 && is_last_frame_blank_ && cur_best == last_best_) {
+      if (cur_best != opts_.blank && is_last_frame_blank_ &&
+          cur_best == last_best_) {
         decodable_.AcceptLoglikes(last_frame_prob_);
         decoder_.AdvanceDecoding(&decodable_, 1);
         decoded_frames_mapping_.push_back(num_frames_ - 1);
@@ -168,7 +169,7 @@ void CtcWfstBeamSearch::ConvertToInputs(const std::vector<int>& alignment,
   if (time != nullptr) time->clear();
   for (int cur = 0; cur < alignment.size(); ++cur) {
     // ignore blank
-    if (alignment[cur] - 1 == 0) continue;
+    if (alignment[cur] - 1 == opts_.blank) continue;
     // merge continuous same label
     if (cur > 0 && alignment[cur] == alignment[cur - 1]) continue;
 

diff --git a/runtime/core/decoder/ctc_wfst_beam_search.h b/runtime/core/decoder/ctc_wfst_beam_search.h
@@ -55,6 +55,7 @@ struct CtcWfstBeamSearchOptions : public kaldi::LatticeFasterDecoderConfig {
   // search
   float blank_skip_thresh = 0.98;
   float blank_scale = 1.0;
+  int blank = 0;
 };
 
 class CtcWfstBeamSearch : public SearchInterface {

diff --git a/runtime/core/decoder/params.h b/runtime/core/decoder/params.h
@@ -88,6 +88,8 @@ DEFINE_int32(min_active, 200, "min active states in ctc wfst search");
 DEFINE_double(beam, 16.0, "beam in ctc wfst search");
 DEFINE_double(lattice_beam, 10.0, "lattice beam in ctc wfst search");
 DEFINE_double(acoustic_scale, 1.0, "acoustic scale for ctc wfst search");
+DEFINE_int32(blank_id, 0,
+             "blank token idx for ctc wfst search and ctc prefix beam search");
 DEFINE_double(blank_skip_thresh, 1.0,
               "blank skip thresh for ctc wfst search, 1.0 means no skip");
 DEFINE_double(blank_scale, 1.0, "blank scale for ctc wfst search");
@@ -145,13 +147,16 @@ std::shared_ptr<DecodeOptions> InitDecodeOptionsFromFlags() {
   decode_config->ctc_wfst_search_opts.beam = FLAGS_beam;
   decode_config->ctc_wfst_search_opts.lattice_beam = FLAGS_lattice_beam;
   decode_config->ctc_wfst_search_opts.acoustic_scale = FLAGS_acoustic_scale;
+  decode_config->ctc_wfst_search_opts.blank = FLAGS_blank_id;
   decode_config->ctc_wfst_search_opts.blank_skip_thresh =
       FLAGS_blank_skip_thresh;
   decode_config->ctc_wfst_search_opts.blank_scale = FLAGS_blank_scale;
   decode_config->ctc_wfst_search_opts.length_penalty = FLAGS_length_penalty;
   decode_config->ctc_wfst_search_opts.nbest = FLAGS_nbest;
   decode_config->ctc_prefix_search_opts.first_beam_size = FLAGS_nbest;
   decode_config->ctc_prefix_search_opts.second_beam_size = FLAGS_nbest;
+  decode_config->ctc_prefix_search_opts.blank = FLAGS_blank_id;
+  decode_config->ctc_endpoint_config.blank = FLAGS_blank_id;
   return decode_config;
 }
 

diff --git a/runtime/core/utils/string.cc b/runtime/core/utils/string.cc
@@ -153,7 +153,7 @@ std::string ProcessBlank(const std::string& str, bool lowercase) {
       std::wstring_convert<std::codecvt_utf8<wchar_t>, wchar_t> converter;
       std::wstring wsresult = converter.from_bytes(result);
       for (auto& c : wsresult) {
-        c = lowercase ? tolower(c, loc) : toupper(c, loc);
+        c = lowercase ? tolower(c, loc) : c;
       }
       result = converter.to_bytes(wsresult);
     } catch (std::exception& e) {