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src/sgmm2/am-sgmm2-project.h 3.39 KB
8dcb6dfcb   Yannick Estève   first commit
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  // sgmm2/am-sgmm2-project.h
  
  // Copyright 2012  Johns Hopkins University (author: Daniel Povey)
  
  // 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_SGMM2_AM_SGMM2_PROJECT_H_
  #define KALDI_SGMM2_AM_SGMM2_PROJECT_H_
  
  #include <vector>
  #include <queue>
  
  #include "sgmm2/am-sgmm2.h"
  
  namespace kaldi {
  
  class Sgmm2Project {
    // This class essentially functions as a namespace for some functions;
    // it's a friend of AmSgmm.h.  It relates to "predictive" SGMMs.  This
    // hasn't been written up yet.  We don't make any functions const or
    // static, because there are no member variables.
   public:
  
    // If inv_lda_mllt is the matrix that projects from the space the SGMM is
    // in, typically back to the spliced-MFCC space, and begin_dim and end_dim
    // represent the range of dims we want to model, then "projection" will be
    // a matrix, applied *after* the "inv_lda_mllt" matrix, that projects from
    // the raw splice-MFCC features to the space we want to model.  This matrix
    // is of dimension e.g. 40 x 117, and omits the space that the model's states
    // all treat the same.
    void ComputeProjection(const AmSgmm2 &sgmm,
                           const Matrix<BaseFloat> &inv_lda_mllt,
                           int32 begin_dim,
                           int32 end_dim, // last dim plus one that we keep.
                           Matrix<BaseFloat> *projection);
  
    // This function applies the feature-space projection to the SGMM.
    // The matrix "total_projection" is the product of the "projection" matrix
    // of ComputeProjection times the "inv_lda_mllt" matrix.  It actually
    // projects from a larger dimension than the current SGMM.  We treat
    // the means as if extended with zeros, and the covariances as if
    // extended with a unit matrix.
    void ApplyProjection(const Matrix<BaseFloat> &total_projection,
                         AmSgmm2 *sgmm);
                           
   private:
    // Computes statistics for LDA, in the SGMM's feature space.
    // This only needs to be approximate, so we use stats based
    // on the means in the UBM.
    void ComputeLdaStats(const FullGmm &full_ubm,
                         SpMatrix<double> *between_covar,
                         SpMatrix<double> *within_covar);
  
    void ProjectVariance (const Matrix<double> &total_projection,
                          bool inverse,
                          SpMatrix<double> *variance);
    
    void ProjectVariance (const Matrix<double> &total_projection,
                          bool inverse,
                          SpMatrix<float> *variance);
    
    void ComputeLdaTransform(const SpMatrix<double> &B,
                             const SpMatrix<double> &W,
                             int32 dim_to_retain, 
                             Matrix<double> *Projection);
    
  };
  
  
  
  } // end namespace kaldi
  
  #endif  // KALDI_SGMM2_AM_SGMM2_PROJECT_H_