diff options
Diffstat (limited to 'kaldi_io/src/kaldi/hmm/hmm-utils.h')
| -rw-r--r-- | kaldi_io/src/kaldi/hmm/hmm-utils.h | 295 |
1 files changed, 295 insertions, 0 deletions
diff --git a/kaldi_io/src/kaldi/hmm/hmm-utils.h b/kaldi_io/src/kaldi/hmm/hmm-utils.h new file mode 100644 index 0000000..240f706 --- /dev/null +++ b/kaldi_io/src/kaldi/hmm/hmm-utils.h @@ -0,0 +1,295 @@ +// hmm/hmm-utils.h + +// Copyright 2009-2011 Microsoft Corporation + +// 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_HMM_HMM_UTILS_H_ +#define KALDI_HMM_HMM_UTILS_H_ + +#include "hmm/hmm-topology.h" +#include "hmm/transition-model.h" +#include "lat/kaldi-lattice.h" + +namespace kaldi { + + +/// \defgroup hmm_group_graph Classes and functions for creating FSTs from HMMs +/// \ingroup hmm_group +/// @{ + +/// Configuration class for the GetHTransducer() function; see +/// \ref hmm_graph_config for context. +struct HTransducerConfig { + /// Transition log-prob scale, see \ref hmm_scale. + /// Note this doesn't apply to self-loops; GetHTransducer() does + /// not include self-loops. + BaseFloat transition_scale; + + /// if true, we are constructing time-reversed FST: phone-seqs in ilabel_info + /// are backwards, and we want to output a backwards version of the HMM + /// corresponding to each phone. If reverse == true, + bool reverse; + + /// This variable is only looked at if reverse == true. If reverse == true + /// and push_weights == true, then we push the weights in the reversed FSTs we create for each + /// phone HMM. This is only safe if the HMMs are probabilistic (i.e. not discriminatively + bool push_weights; + + /// delta used if we do push_weights [only relevant if reverse == true + /// and push_weights == true]. + BaseFloat push_delta; + + HTransducerConfig(): + transition_scale(1.0), + reverse(false), + push_weights(true), + push_delta(0.001) + { } + + // Note-- this Register registers the easy-to-register options + // but not the "sym_type" which is an enum and should be handled + // separately in main(). + void Register (OptionsItf *po) { + po->Register("transition-scale", &transition_scale, + "Scale of transition probs (relative to LM)"); + po->Register("reverse", &reverse, + "Set true to build time-reversed FST."); + po->Register("push-weights", &push_weights, + "Push weights (only applicable if reverse == true)"); + po->Register("push-delta", &push_delta, + "Delta used in pushing weights (only applicable if " + "reverse && push-weights"); + } +}; + + +struct HmmCacheHash { + int operator () (const std::pair<int32, std::vector<int32> >&p) const { + VectorHasher<int32> v; + int32 prime = 103049; + return prime*p.first + v(p.second); + } +}; + +/// HmmCacheType is a map from (central-phone, sequence of pdf-ids) to FST, used +/// as cache in GetHmmAsFst, as an optimization. +typedef unordered_map<std::pair<int32, std::vector<int32> >, + fst::VectorFst<fst::StdArc>*, + HmmCacheHash> HmmCacheType; + + +/// Called by GetHTransducer() and probably will not need to be called directly; +/// it creates the FST corresponding to the phone. Does not include self-loops; +/// you have to call AddSelfLoops() for that. Result owned by caller. +/// Returns an acceptor (i.e. ilabels, olabels identical) with transition-ids +/// as the symbols. +/// For documentation in context, see \ref hmm_graph_get_hmm_as_fst +/// @param context_window A vector representing the phonetic context; see +/// \ref tree_window "here" for explanation. +/// @param ctx_dep The object that contains the phonetic decision-tree +/// @param trans_model The transition-model object, which provides +/// the mappings to transition-ids and also the transition +/// probabilities. +/// @param config Configuration object, see \ref HTransducerConfig. +/// @param cache Object used as a lookaside buffer to save computation; +/// if it finds that the object it needs is already there, it will +/// just return a pointer value from "cache"-- not that this means +/// you have to be careful not to delete things twice. + +fst::VectorFst<fst::StdArc> *GetHmmAsFst( + std::vector<int32> context_window, + const ContextDependencyInterface &ctx_dep, + const TransitionModel &trans_model, + const HTransducerConfig &config, + HmmCacheType *cache = NULL); + +/// Included mainly as a form of documentation, not used in any other code +/// currently. Creates the FST with self-loops, and with fewer options. +fst::VectorFst<fst::StdArc>* +GetHmmAsFstSimple(std::vector<int32> context_window, + const ContextDependencyInterface &ctx_dep, + const TransitionModel &trans_model, + BaseFloat prob_scale); + + +/** + * Returns the H tranducer; result owned by caller. + * See \ref hmm_graph_get_h_transducer. The H transducer has on the + * input transition-ids, and also possibly some disambiguation symbols, which + * will be put in disambig_syms. The output side contains the identifiers that + * are indexes into "ilabel_info" (these represent phones-in-context or + * disambiguation symbols). The ilabel_info vector allows GetHTransducer to map + * from symbols to phones-in-context (i.e. phonetic context windows). Any + * singleton symbols in the ilabel_info vector which are not phones, will be + * treated as disambiguation symbols. [Not all recipes use these]. The output + * "disambig_syms_left" will be set to a list of the disambiguation symbols on + * the input of the transducer (i.e. same symbol type as whatever is on the + * input of the transducer + */ +fst::VectorFst<fst::StdArc>* +GetHTransducer (const std::vector<std::vector<int32> > &ilabel_info, + const ContextDependencyInterface &ctx_dep, + const TransitionModel &trans_model, + const HTransducerConfig &config, + std::vector<int32> *disambig_syms_left); + +/** + * GetIlabelMapping produces a mapping that's similar to HTK's logical-to-physical + * model mapping (i.e. the xwrd.clustered.mlist files). It groups together + * "logical HMMs" (i.e. in our world, phonetic context windows) that share the + * same sequence of transition-ids. This can be used in an + * optional graph-creation step that produces a remapped form of CLG that can be + * more productively determinized and minimized. This is used in the command-line program + * make-ilabel-transducer.cc. + * @param ilabel_info_old [in] The original \ref tree_ilabel "ilabel_info" vector + * @param ctx_dep [in] The tree + * @param trans_model [in] The transition-model object + * @param old2new_map [out] The output; this vector, which is of size equal to the + * number of new labels, is a mapping to the old labels such that we could + * create a vector ilabel_info_new such that + * ilabel_info_new[i] == ilabel_info_old[old2new_map[i]] + */ +void GetIlabelMapping (const std::vector<std::vector<int32> > &ilabel_info_old, + const ContextDependencyInterface &ctx_dep, + const TransitionModel &trans_model, + std::vector<int32> *old2new_map); + + + +/** + * For context, see \ref hmm_graph_add_self_loops. Expands an FST that has been + * built without self-loops, and adds the self-loops (it also needs to modify + * the probability of the non-self-loop ones, as the graph without self-loops + * was created in such a way that it was stochastic). Note that the + * disambig_syms will be empty in some recipes (e.g. if you already removed + * the disambiguation symbols). + * @param trans_model [in] Transition model + * @param disambig_syms [in] Sorted, uniq list of disambiguation symbols, required + * if the graph contains disambiguation symbols but only needed for sanity checks. + * @param self_loop_scale [in] Transition-probability scale for self-loops; c.f. + * \ref hmm_scale + * @param reorder [in] If true, reorders the transitions (see \ref hmm_reorder). + * @param fst [in, out] The FST to be modified. + */ +void AddSelfLoops(const TransitionModel &trans_model, + const std::vector<int32> &disambig_syms, // used as a check only. + BaseFloat self_loop_scale, + bool reorder, // true->dan-style, false->lukas-style. + fst::VectorFst<fst::StdArc> *fst); + +/** + * Adds transition-probs, with the supplied + * scales (see \ref hmm_scale), to the graph. + * Useful if you want to create a graph without transition probs, then possibly + * train the model (including the transition probs) but keep the graph fixed, + * and add back in the transition probs. It assumes the fst has transition-ids + * on it. It is not an error if the FST has no states (nothing will be done). + * @param trans_model [in] The transition model + * @param disambig_syms [in] A list of disambiguation symbols, required if the + * graph has disambiguation symbols on its input but only + * used for checks. + * @param transition_scale [in] A scale on transition-probabilities apart from + * those involving self-loops; see \ref hmm_scale. + * @param self_loop_scale [in] A scale on self-loop transition probabilities; + * see \ref hmm_scale. + * @param fst [in, out] The FST to be modified. + */ +void AddTransitionProbs(const TransitionModel &trans_model, + const std::vector<int32> &disambig_syms, + BaseFloat transition_scale, + BaseFloat self_loop_scale, + fst::VectorFst<fst::StdArc> *fst); + +/** + This is as AddSelfLoops(), but operates on a Lattice, where + it affects the graph part of the weight (the first element + of the pair). */ +void AddTransitionProbs(const TransitionModel &trans_model, + BaseFloat transition_scale, + BaseFloat self_loop_scale, + Lattice *lat); + + +/// Returns a transducer from pdfs plus one (input) to transition-ids (output). +/// Currenly of use only for testing. +fst::VectorFst<fst::StdArc>* +GetPdfToTransitionIdTransducer(const TransitionModel &trans_model); + +/// Converts all transition-ids in the FST to pdfs plus one. +/// Placeholder: not implemented yet! +void ConvertTransitionIdsToPdfs(const TransitionModel &trans_model, + const std::vector<int32> &disambig_syms, + fst::VectorFst<fst::StdArc> *fst); + +/// @} end "defgroup hmm_group_graph" + +/// \addtogroup hmm_group +/// @{ + +/// SplitToPhones splits up the TransitionIds in "alignment" into their +/// individual phones (one vector per instance of a phone). At output, +/// the sum of the sizes of the vectors in split_alignment will be the same +/// as the corresponding sum for "alignment". The function returns +/// true on success. If the alignment appears to be incomplete, e.g. +/// not ending at the end-state of a phone, it will still break it up into +/// phones but it will return false. For more serious errors it will +/// die or throw an exception. +/// This function works out by itself whether the graph was created +/// with "reordering" (dan-style graph), and just does the right thing. + +bool SplitToPhones(const TransitionModel &trans_model, + const std::vector<int32> &alignment, + std::vector<std::vector<int32> > *split_alignment); + +/// ConvertAlignment converts an alignment that was created using one +/// model, to another model. They must use a compatible topology (so we +/// know the state alignments of the new model). +/// It returns false if it could not be split to phones (probably +/// because the alignment was partial), but for other kinds of +/// error that are more likely a coding error, it will throw +/// an exception. +bool ConvertAlignment(const TransitionModel &old_trans_model, + const TransitionModel &new_trans_model, + const ContextDependencyInterface &new_ctx_dep, + const std::vector<int32> &old_alignment, + const std::vector<int32> *phone_map, // may be NULL + std::vector<int32> *new_alignment); + +// ConvertPhnxToProns is only needed in bin/phones-to-prons.cc and +// isn't closely related with HMMs, but we put it here as there isn't +// any other obvious place for it and it needs to be tested. +// This function takes a phone-sequence with word-start and word-end +// markers in it, and a word-sequence, and outputs the pronunciations +// "prons"... the format of "prons" is, each element is a vector, +// where the first element is the word (or zero meaning no word, e.g. +// for optional silence introduced by the lexicon), and the remaining +// elements are the phones in the word's pronunciation. +// It returns false if it encounters a problem of some kind, e.g. +// if the phone-sequence doesn't seem to have the right number of +// words in it. +bool ConvertPhnxToProns(const std::vector<int32> &phnx, + const std::vector<int32> &words, + int32 word_start_sym, + int32 word_end_sym, + std::vector<std::vector<int32> > *prons); + +/// @} end "addtogroup hmm_group" + +} // end namespace kaldi + + +#endif |