This online-feature class implements any affine or linear transform. More...

#include <online-feature.h>

Inheritance diagram for OnlineTransform:

Collaboration diagram for OnlineTransform:

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Public Member Functions
virtual int32	Dim () const

virtual bool	IsLastFrame (int32 frame) const
	Returns true if this is the last frame. More...

virtual BaseFloat	FrameShiftInSeconds () const

virtual int32	NumFramesReady () const
	returns the feature dimension. More...

virtual void	GetFrame (int32 frame, VectorBase< BaseFloat > *feat)
	Gets the feature vector for this frame. More...

virtual void	GetFrames (const std::vector< int32 > &frames, MatrixBase< BaseFloat > *feats)
	This is like GetFrame() but for a collection of frames. More...

	OnlineTransform (const MatrixBase< BaseFloat > &transform, OnlineFeatureInterface *src)
	The transform can be a linear transform, or an affine transform where the last column is the offset. More...

Public Member Functions inherited from OnlineFeatureInterface
virtual	~OnlineFeatureInterface ()
	Virtual destructor. More...

Private Attributes
OnlineFeatureInterface *	src_

Matrix< BaseFloat >	linear_term_

Vector< BaseFloat >	offset_

Detailed Description

This online-feature class implements any affine or linear transform.

Definition at line 493 of file online-feature.h.

Constructor & Destructor Documentation

◆ OnlineTransform()

OnlineTransform	(	const MatrixBase< BaseFloat > &	transform,
		OnlineFeatureInterface *	src
	)

The transform can be a linear transform, or an affine transform where the last column is the offset.

Definition at line 521 of file online-feature.cc.

References OnlineFeatureInterface::Dim(), KALDI_ERR, OnlineTransform::linear_term_, MatrixBase< Real >::NumCols(), MatrixBase< Real >::NumRows(), OnlineTransform::offset_, MatrixBase< Real >::Range(), and OnlineTransform::src_.

                                                              :
     src_(src) {
   int32 src_dim = src_->Dim();
   if (transform.NumCols() == src_dim) {  // Linear transform
     linear_term_ = transform;
     offset_.Resize(transform.NumRows());  // Resize() will zero it.
   } else if (transform.NumCols() == src_dim + 1) {  // Affine transform
     linear_term_ = transform.Range(0, transform.NumRows(), 0, src_dim);
     offset_.Resize(transform.NumRows());
     offset_.CopyColFromMat(transform, src_dim);
   } else {
     KALDI_ERR << "Dimension mismatch: source features have dimension "
               << src_dim << " and LDA #cols is " << transform.NumCols();
   }
 }

Member Function Documentation

◆ Dim()

virtual int32 Dim ( ) const

inlinevirtual

Implements OnlineFeatureInterface.

Definition at line 498 of file online-feature.h.

Referenced by OnlineDeltaFeature::GetFrame().

498 { return offset_.Dim(); }

kaldi::OnlineTransform::offset_

Vector< BaseFloat > offset_

Definition: online-feature.h:527

◆ FrameShiftInSeconds()

virtual BaseFloat FrameShiftInSeconds ( ) const

inlinevirtual

Implements OnlineFeatureInterface.

Definition at line 503 of file online-feature.h.

                                                 {
     return src_->FrameShiftInSeconds();
   }

◆ GetFrame()

void GetFrame	(	int32	frame,
		VectorBase< BaseFloat > *	feat
	)

virtual

Gets the feature vector for this frame.

Before calling this for a given frame, it is assumed that you called NumFramesReady() and it returned a number greater than "frame". Otherwise this call will likely crash with an assert failure. This function is not declared const, in case there is some kind of caching going on, but most of the time it shouldn't modify the class.

Implements OnlineFeatureInterface.

Definition at line 538 of file online-feature.cc.

References VectorBase< Real >::AddMatVec(), VectorBase< Real >::CopyFromVec(), OnlineFeatureInterface::GetFrame(), kaldi::kNoTrans, OnlineTransform::linear_term_, MatrixBase< Real >::NumCols(), OnlineTransform::offset_, and OnlineTransform::src_.

                                                                        {
   Vector<BaseFloat> input_feat(linear_term_.NumCols());
   src_->GetFrame(frame, &input_feat);
   feat->CopyFromVec(offset_);
   feat->AddMatVec(1.0, linear_term_, kNoTrans, input_feat, 1.0);
 }

◆ GetFrames()

void GetFrames	(	const std::vector< int32 > &	frames,
		MatrixBase< BaseFloat > *	feats
	)

virtual

This is like GetFrame() but for a collection of frames.

There is a default implementation that just gets the frames one by one, but it may be overridden for efficiency by child classes (since sometimes it's more efficient to do things in a batch).

Reimplemented from OnlineFeatureInterface.

Definition at line 545 of file online-feature.cc.

References MatrixBase< Real >::AddMatMat(), MatrixBase< Real >::CopyRowsFromVec(), OnlineFeatureInterface::GetFrames(), KALDI_ASSERT, kaldi::kNoTrans, kaldi::kTrans, kaldi::kUndefined, OnlineTransform::linear_term_, MatrixBase< Real >::NumCols(), MatrixBase< Real >::NumRows(), OnlineTransform::offset_, and OnlineTransform::src_.

                                                                   {
   KALDI_ASSERT(static_cast<int32>(frames.size()) == feats->NumRows());
   int32 num_frames = feats->NumRows(),
       input_dim = linear_term_.NumCols();
   Matrix<BaseFloat> input_feats(num_frames, input_dim, kUndefined);
   src_->GetFrames(frames, &input_feats);
   feats->CopyRowsFromVec(offset_);
   feats->AddMatMat(1.0, input_feats, kNoTrans, linear_term_, kTrans, 1.0);
 }

◆ IsLastFrame()

virtual bool IsLastFrame ( int32 frame ) const

inlinevirtual

Returns true if this is the last frame.

Frame indices are zero-based, so the first frame is zero. IsLastFrame(-1) will return false, unless the file is empty (which is a case that I'm not sure all the code will handle, so be careful). This function may return false for some frame if we haven't yet decided to terminate decoding, but later true if we decide to terminate decoding. This function exists mainly to correctly handle end effects in feature extraction, and is not a mechanism to determine how many frames are in the decodable object (as it used to be, and for backward compatibility, still is, in the Decodable interface).

Implements OnlineFeatureInterface.

Definition at line 500 of file online-feature.h.

                                               {
     return src_->IsLastFrame(frame);
   }

◆ NumFramesReady()

virtual int32 NumFramesReady ( ) const

inlinevirtual

returns the feature dimension.

Returns the total number of frames, since the start of the utterance, that are now available. In an online-decoding context, this will likely increase with time as more data becomes available.

Implements OnlineFeatureInterface.

Definition at line 507 of file online-feature.h.

Referenced by OnlineDeltaFeature::GetFrame().

507 { return src_->NumFramesReady(); }

kaldi::OnlineTransform::src_

OnlineFeatureInterface * src_

Definition: online-feature.h:525

kaldi::OnlineFeatureInterface::NumFramesReady

virtual int32 NumFramesReady() const =0

returns the feature dimension.