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94 lines
3.2 KiB
94 lines
3.2 KiB
// Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "base/common.h"
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#include "decoder/ctc_decoders/path_trie.h"
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#include "decoder/ctc_decoders/scorer.h"
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#include "nnet/decodable-itf.h"
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#include "util/parse-options.h"
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#pragma once
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namespace ppspeech {
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struct CTCBeamSearchOptions {
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std::string dict_file;
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std::string lm_path;
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BaseFloat alpha;
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BaseFloat beta;
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BaseFloat cutoff_prob;
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int beam_size;
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int cutoff_top_n;
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int num_proc_bsearch;
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CTCBeamSearchOptions()
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: dict_file("vocab.txt"),
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lm_path("lm.klm"),
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alpha(1.9f),
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beta(5.0),
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beam_size(300),
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cutoff_prob(0.99f),
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cutoff_top_n(40),
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num_proc_bsearch(0) {}
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void Register(kaldi::OptionsItf* opts) {
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opts->Register("dict", &dict_file, "dict file ");
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opts->Register("lm-path", &lm_path, "language model file");
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opts->Register("alpha", &alpha, "alpha");
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opts->Register("beta", &beta, "beta");
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opts->Register(
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"beam-size", &beam_size, "beam size for beam search method");
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opts->Register("cutoff-prob", &cutoff_prob, "cutoff probs");
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opts->Register("cutoff-top-n", &cutoff_top_n, "cutoff top n");
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opts->Register(
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"num-proc-bsearch", &num_proc_bsearch, "num proc bsearch");
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}
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};
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class CTCBeamSearch {
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public:
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explicit CTCBeamSearch(const CTCBeamSearchOptions& opts);
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~CTCBeamSearch() {}
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void InitDecoder();
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void Decode(std::shared_ptr<kaldi::DecodableInterface> decodable);
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std::string GetBestPath();
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std::vector<std::pair<double, std::string>> GetNBestPath();
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std::string GetFinalBestPath();
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int NumFrameDecoded();
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int DecodeLikelihoods(const std::vector<std::vector<BaseFloat>>& probs,
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std::vector<std::string>& nbest_words);
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void AdvanceDecode(
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const std::shared_ptr<kaldi::DecodableInterface>& decodable);
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void Reset();
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private:
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void ResetPrefixes();
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int32 SearchOneChar(const bool& full_beam,
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const std::pair<size_t, BaseFloat>& log_prob_idx,
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const BaseFloat& min_cutoff);
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void CalculateApproxScore();
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void LMRescore();
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void AdvanceDecoding(const std::vector<std::vector<BaseFloat>>& probs);
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CTCBeamSearchOptions opts_;
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std::shared_ptr<Scorer> init_ext_scorer_; // todo separate later
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std::vector<std::string> vocabulary_; // todo remove later
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size_t blank_id_;
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int space_id_;
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std::shared_ptr<PathTrie> root_;
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std::vector<PathTrie*> prefixes_;
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int num_frame_decoded_;
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DISALLOW_COPY_AND_ASSIGN(CTCBeamSearch);
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};
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} // namespace basr
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