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diff --git a/kaldi_io/src/kaldi/hmm/transition-model.h b/kaldi_io/src/kaldi/hmm/transition-model.h new file mode 100644 index 0000000..ccc4f11 --- /dev/null +++ b/kaldi_io/src/kaldi/hmm/transition-model.h @@ -0,0 +1,345 @@ +// hmm/transition-model.h + +// Copyright 2009-2012 Microsoft Corporation +// Johns Hopkins University (author: Guoguo Chen) + +// 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_TRANSITION_MODEL_H_ +#define KALDI_HMM_TRANSITION_MODEL_H_ + +#include "base/kaldi-common.h" +#include "tree/context-dep.h" +#include "util/const-integer-set.h" +#include "fst/fst-decl.h" // forward declarations. +#include "hmm/hmm-topology.h" +#include "itf/options-itf.h" + +namespace kaldi { + +/// \addtogroup hmm_group +/// @{ + +// The class TransitionModel is a repository for the transition probabilities. +// It also handles certain integer mappings. +// The basic model is as follows. Each phone has a HMM topology defined in +// hmm-topology.h. Each HMM-state of each of these phones has a number of +// transitions (and final-probs) out of it. Each HMM-state defined in the +// HmmTopology class has an associated "pdf_class". This gets replaced with +// an actual pdf-id via the tree. The transition model associates the +// transition probs with the (phone, HMM-state, pdf-id). We associate with +// each such triple a transition-state. Each +// transition-state has a number of associated probabilities to estimate; +// this depends on the number of transitions/final-probs in the topology for +// that (phone, HMM-state). Each probability has an associated transition-index. +// We associate with each (transition-state, transition-index) a unique transition-id. +// Each individual probability estimated by the transition-model is asociated with a +// transition-id. +// +// List of the various types of quantity referred to here and what they mean: +// phone: a phone index (1, 2, 3 ...) +// HMM-state: a number (0, 1, 2...) that indexes TopologyEntry (see hmm-topology.h) +// pdf-id: a number output by the Compute function of ContextDependency (it +// indexes pdf's). Zero-based. +// transition-state: the states for which we estimate transition probabilities for transitions +// out of them. In some topologies, will map one-to-one with pdf-ids. +// One-based, since it appears on FSTs. +// transition-index: identifier of a transition (or final-prob) in the HMM. Indexes the +// "transitions" vector in HmmTopology::HmmState. [if it is out of range, +// equal to transitions.size(), it refers to the final-prob.] +// Zero-based. +// transition-id: identifier of a unique parameter of the TransitionModel. +// Associated with a (transition-state, transition-index) pair. +// One-based, since it appears on FSTs. +// +// List of the possible mappings TransitionModel can do: +// (phone, HMM-state, pdf-id) -> transition-state +// (transition-state, transition-index) -> transition-id +// Reverse mappings: +// transition-id -> transition-state +// transition-id -> transition-index +// transition-state -> phone +// transition-state -> HMM-state +// transition-state -> pdf-id +// +// The main things the TransitionModel object can do are: +// Get initialized (need ContextDependency and HmmTopology objects). +// Read/write. +// Update [given a vector of counts indexed by transition-id]. +// Do the various integer mappings mentioned above. +// Get the probability (or log-probability) associated with a particular transition-id. + + +// Note: this was previously called TransitionUpdateConfig. +struct MleTransitionUpdateConfig { + BaseFloat floor; + BaseFloat mincount; + bool share_for_pdfs; // If true, share all transition parameters that have the same pdf. + MleTransitionUpdateConfig(BaseFloat floor = 0.01, + BaseFloat mincount = 5.0, + bool share_for_pdfs = false): + floor(floor), mincount(mincount), share_for_pdfs(share_for_pdfs) {} + + void Register (OptionsItf *po) { + po->Register("transition-floor", &floor, + "Floor for transition probabilities"); + po->Register("transition-min-count", &mincount, + "Minimum count required to update transitions from a state"); + po->Register("share-for-pdfs", &share_for_pdfs, + "If true, share all transition parameters where the states " + "have the same pdf."); + } +}; + +struct MapTransitionUpdateConfig { + BaseFloat tau; + bool share_for_pdfs; // If true, share all transition parameters that have the same pdf. + MapTransitionUpdateConfig(): tau(5.0), share_for_pdfs(false) { } + + void Register (OptionsItf *po) { + po->Register("transition-tau", &tau, "Tau value for MAP estimation of transition " + "probabilities."); + po->Register("share-for-pdfs", &share_for_pdfs, + "If true, share all transition parameters where the states " + "have the same pdf."); + } +}; + +class TransitionModel { + + public: + /// Initialize the object [e.g. at the start of training]. + /// The class keeps a copy of the HmmTopology object, but not + /// the ContextDependency object. + TransitionModel(const ContextDependency &ctx_dep, + const HmmTopology &hmm_topo); + + + /// Constructor that takes no arguments: typically used prior to calling Read. + TransitionModel() { } + + void Read(std::istream &is, bool binary); // note, no symbol table: topo object always read/written w/o symbols. + void Write(std::ostream &os, bool binary) const; + + + /// return reference to HMM-topology object. + const HmmTopology &GetTopo() const { return topo_; } + + /// \name Integer mapping functions + /// @{ + + int32 TripleToTransitionState(int32 phone, int32 hmm_state, int32 pdf) const; + int32 PairToTransitionId(int32 trans_state, int32 trans_index) const; + int32 TransitionIdToTransitionState(int32 trans_id) const; + int32 TransitionIdToTransitionIndex(int32 trans_id) const; + int32 TransitionStateToPhone(int32 trans_state) const; + int32 TransitionStateToHmmState(int32 trans_state) const; + int32 TransitionStateToPdf(int32 trans_state) const; + int32 SelfLoopOf(int32 trans_state) const; // returns the self-loop transition-id, or zero if + // this state doesn't have a self-loop. + + inline int32 TransitionIdToPdf(int32 trans_id) const; + int32 TransitionIdToPhone(int32 trans_id) const; + int32 TransitionIdToPdfClass(int32 trans_id) const; + int32 TransitionIdToHmmState(int32 trans_id) const; + + /// @} + + bool IsFinal(int32 trans_id) const; // returns true if this trans_id goes to the final state + // (which is bound to be nonemitting). + bool IsSelfLoop(int32 trans_id) const; // return true if this trans_id corresponds to a self-loop. + + /// Returns the total number of transition-ids (note, these are one-based). + inline int32 NumTransitionIds() const { return id2state_.size()-1; } + + /// Returns the number of transition-indices for a particular transition-state. + /// Note: "Indices" is the plural of "index". Index is not the same as "id", + /// here. A transition-index is a zero-based offset into the transitions + /// out of a particular transition state. + int32 NumTransitionIndices(int32 trans_state) const; + + /// Returns the total number of transition-states (note, these are one-based). + int32 NumTransitionStates() const { return triples_.size(); } + + // NumPdfs() actually returns the highest-numbered pdf we ever saw, plus one. + // In normal cases this should equal the number of pdfs in the system, but if you + // initialized this object with fewer than all the phones, and it happens that + // an unseen phone has the highest-numbered pdf, this might be different. + int32 NumPdfs() const { return num_pdfs_; } + + // This loops over the triples and finds the highest phone index present. If + // the FST symbol table for the phones is created in the expected way, i.e.: + // starting from 1 (<eps> is 0) and numbered contiguously till the last phone, + // this will be the total number of phones. + int32 NumPhones() const; + + /// Returns a sorted, unique list of phones. + const std::vector<int32> &GetPhones() const { return topo_.GetPhones(); } + + // Transition-parameter-getting functions: + BaseFloat GetTransitionProb(int32 trans_id) const; + BaseFloat GetTransitionLogProb(int32 trans_id) const; + + // The following functions are more specialized functions for getting + // transition probabilities, that are provided for convenience. + + /// Returns the log-probability of a particular non-self-loop transition + /// after subtracting the probability mass of the self-loop and renormalizing; + /// will crash if called on a self-loop. Specifically: + /// for non-self-loops it returns the log of that prob divided by (1 minus + /// self-loop-prob-for-that-state). + BaseFloat GetTransitionLogProbIgnoringSelfLoops(int32 trans_id) const; + + /// Returns the log-prob of the non-self-loop probability + /// mass for this transition state. (you can get the self-loop prob, if a self-loop + /// exists, by calling GetTransitionLogProb(SelfLoopOf(trans_state)). + BaseFloat GetNonSelfLoopLogProb(int32 trans_state) const; + + /// Does Maximum Likelihood estimation. The stats are counts/weights, indexed + /// by transition-id. This was previously called Update(). + void MleUpdate(const Vector<double> &stats, + const MleTransitionUpdateConfig &cfg, + BaseFloat *objf_impr_out, + BaseFloat *count_out); + + /// Does Maximum A Posteriori (MAP) estimation. The stats are counts/weights, + /// indexed by transition-id. + void MapUpdate(const Vector<double> &stats, + const MapTransitionUpdateConfig &cfg, + BaseFloat *objf_impr_out, + BaseFloat *count_out); + + /// Print will print the transition model in a human-readable way, for purposes of human + /// inspection. The "occs" are optional (they are indexed by pdf-id). + void Print(std::ostream &os, + const std::vector<std::string> &phone_names, + const Vector<double> *occs = NULL); + + + void InitStats(Vector<double> *stats) const { stats->Resize(NumTransitionIds()+1); } + + void Accumulate(BaseFloat prob, int32 trans_id, Vector<double> *stats) const { + KALDI_ASSERT(trans_id <= NumTransitionIds()); + (*stats)(trans_id) += prob; + // This is trivial and doesn't require class members, but leaves us more open + // to design changes than doing it manually. + } + + /// returns true if all the integer class members are identical (but does not + /// compare the transition probabilities. + bool Compatible(const TransitionModel &other) const; + + private: + void MleUpdateShared(const Vector<double> &stats, + const MleTransitionUpdateConfig &cfg, + BaseFloat *objf_impr_out, BaseFloat *count_out); + void MapUpdateShared(const Vector<double> &stats, + const MapTransitionUpdateConfig &cfg, + BaseFloat *objf_impr_out, BaseFloat *count_out); + void ComputeTriples(const ContextDependency &ctx_dep); // called from constructor. initializes triples_. + void ComputeDerived(); // called from constructor and Read function: computes state2id_ and id2state_. + void ComputeDerivedOfProbs(); // computes quantities derived from log-probs (currently just + // non_self_loop_log_probs_; called whenever log-probs change. + void InitializeProbs(); // called from constructor. + void Check() const; + + struct Triple { + int32 phone; + int32 hmm_state; + int32 pdf; + Triple() { } + Triple(int32 phone, int32 hmm_state, int32 pdf): + phone(phone), hmm_state(hmm_state), pdf(pdf) { } + bool operator < (const Triple &other) const { + if (phone < other.phone) return true; + else if (phone > other.phone) return false; + else if (hmm_state < other.hmm_state) return true; + else if (hmm_state > other.hmm_state) return false; + else return pdf < other.pdf; + } + bool operator == (const Triple &other) const { + return (phone == other.phone && hmm_state == other.hmm_state + && pdf == other.pdf); + } + }; + + HmmTopology topo_; + + /// Triples indexed by transition state minus one; + /// the triples are in sorted order which allows us to do the reverse mapping from + /// triple to transition state + std::vector<Triple> triples_; + + /// Gives the first transition_id of each transition-state; indexed by + /// the transition-state. Array indexed 1..num-transition-states+1 (the last one + /// is needed so we can know the num-transitions of the last transition-state. + std::vector<int32> state2id_; + + /// For each transition-id, the corresponding transition + /// state (indexed by transition-id). + std::vector<int32> id2state_; + + /// For each transition-id, the corresponding log-prob. Indexed by transition-id. + Vector<BaseFloat> log_probs_; + + /// For each transition-state, the log of (1 - self-loop-prob). Indexed by + /// transition-state. + Vector<BaseFloat> non_self_loop_log_probs_; + + /// This is actually one plus the highest-numbered pdf we ever got back from the + /// tree (but the tree numbers pdfs contiguously from zero so this is the number + /// of pdfs). + int32 num_pdfs_; + + + DISALLOW_COPY_AND_ASSIGN(TransitionModel); + +}; + +inline int32 TransitionModel::TransitionIdToPdf(int32 trans_id) const { + // If a lot of time is spent here we may create an extra array + // to handle this. + KALDI_ASSERT(static_cast<size_t>(trans_id) < id2state_.size() && + "Likely graph/model mismatch (graph built from wrong model?)"); + int32 trans_state = id2state_[trans_id]; + return triples_[trans_state-1].pdf; +} + +/// Works out which pdfs might correspond to the given phones. Will return true +/// if these pdfs correspond *just* to these phones, false if these pdfs are also +/// used by other phones. +/// @param trans_model [in] Transition-model used to work out this information +/// @param phones [in] A sorted, uniq vector that represents a set of phones +/// @param pdfs [out] Will be set to a sorted, uniq list of pdf-ids that correspond +/// to one of this set of phones. +/// @return Returns true if all of the pdfs output to "pdfs" correspond to phones from +/// just this set (false if they may be shared with phones outside this set). +bool GetPdfsForPhones(const TransitionModel &trans_model, + const std::vector<int32> &phones, + std::vector<int32> *pdfs); + +/// Works out which phones might correspond to the given pdfs. Similar to the +/// above GetPdfsForPhones(, ,) +bool GetPhonesForPdfs(const TransitionModel &trans_model, + const std::vector<int32> &pdfs, + std::vector<int32> *phones); +/// @} + + +} // end namespace kaldi + + +#endif |