online-nnet3-decoding.h
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// online2/online-nnet3-decoding.h
// Copyright 2014 Johns Hopkins University (author: Daniel Povey)
// 2016 Api.ai (Author: Ilya Platonov)
// See ../../COPYING for clarification regarding multiple authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// THIS CODE IS PROVIDED *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
// WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
// MERCHANTABLITY OR NON-INFRINGEMENT.
// See the Apache 2 License for the specific language governing permissions and
// limitations under the License.
#ifndef KALDI_ONLINE2_ONLINE_NNET3_DECODING_H_
#define KALDI_ONLINE2_ONLINE_NNET3_DECODING_H_
#include <string>
#include <vector>
#include <deque>
#include "nnet3/decodable-online-looped.h"
#include "matrix/matrix-lib.h"
#include "util/common-utils.h"
#include "base/kaldi-error.h"
#include "itf/online-feature-itf.h"
#include "online2/online-endpoint.h"
#include "online2/online-nnet2-feature-pipeline.h"
#include "decoder/lattice-faster-online-decoder.h"
#include "hmm/transition-model.h"
#include "hmm/posterior.h"
namespace kaldi {
/// @addtogroup onlinedecoding OnlineDecoding
/// @{
/**
You will instantiate this class when you want to decode a single utterance
using the online-decoding setup for neural nets. The template will be
instantiated only for FST = fst::Fst<fst::StdArc> and FST = fst::GrammarFst.
*/
template <typename FST>
class SingleUtteranceNnet3DecoderTpl {
public:
// Constructor. The pointer 'features' is not being given to this class to own
// and deallocate, it is owned externally.
SingleUtteranceNnet3DecoderTpl(const LatticeFasterDecoderConfig &decoder_opts,
const TransitionModel &trans_model,
const nnet3::DecodableNnetSimpleLoopedInfo &info,
const FST &fst,
OnlineNnet2FeaturePipeline *features);
/// Initializes the decoding and sets the frame offset of the underlying
/// decodable object. This method is called by the constructor. You can also
/// call this method when you want to reset the decoder state, but want to
/// keep using the same decodable object, e.g. in case of an endpoint.
void InitDecoding(int32 frame_offset = 0);
/// Advances the decoding as far as we can.
void AdvanceDecoding();
/// Finalizes the decoding. Cleans up and prunes remaining tokens, so the
/// GetLattice() call will return faster. You must not call this before
/// calling (TerminateDecoding() or InputIsFinished()) and then Wait().
void FinalizeDecoding();
int32 NumFramesDecoded() const;
/// Gets the lattice. The output lattice has any acoustic scaling in it
/// (which will typically be desirable in an online-decoding context); if you
/// want an un-scaled lattice, scale it using ScaleLattice() with the inverse
/// of the acoustic weight. "end_of_utterance" will be true if you want the
/// final-probs to be included.
void GetLattice(bool end_of_utterance,
CompactLattice *clat) const;
/// Outputs an FST corresponding to the single best path through the current
/// lattice. If "use_final_probs" is true AND we reached the final-state of
/// the graph then it will include those as final-probs, else it will treat
/// all final-probs as one.
void GetBestPath(bool end_of_utterance,
Lattice *best_path) const;
/// This function calls EndpointDetected from online-endpoint.h,
/// with the required arguments.
bool EndpointDetected(const OnlineEndpointConfig &config);
const LatticeFasterOnlineDecoderTpl<FST> &Decoder() const { return decoder_; }
~SingleUtteranceNnet3DecoderTpl() { }
private:
const LatticeFasterDecoderConfig &decoder_opts_;
// this is remembered from the constructor; it's ultimately
// derived from calling FrameShiftInSeconds() on the feature pipeline.
BaseFloat input_feature_frame_shift_in_seconds_;
// we need to keep a reference to the transition model around only because
// it's needed by the endpointing code.
const TransitionModel &trans_model_;
nnet3::DecodableAmNnetLoopedOnline decodable_;
LatticeFasterOnlineDecoderTpl<FST> decoder_;
};
typedef SingleUtteranceNnet3DecoderTpl<fst::Fst<fst::StdArc> > SingleUtteranceNnet3Decoder;
/// @} End of "addtogroup onlinedecoding"
} // namespace kaldi
#endif // KALDI_ONLINE2_ONLINE_NNET3_DECODING_H_