OnlineSpliceFrames Class Reference

#include <online-feature.h>

Inheritance diagram for OnlineSpliceFrames:

Collaboration diagram for OnlineSpliceFrames:

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...
	OnlineSpliceFrames (const OnlineSpliceOptions &opts, OnlineFeatureInterface *src)
Public Member Functions inherited from OnlineFeatureInterface
virtual void	GetFrames (const std::vector< int32 > &frames, MatrixBase< BaseFloat > *feats)
	This is like GetFrame() but for a collection of frames. More...
virtual	~OnlineFeatureInterface ()
	Virtual destructor. More...

Private Attributes
int32	left_context_
int32	right_context_
OnlineFeatureInterface *	src_

Detailed Description

Definition at line 458 of file online-feature.h.

Constructor & Destructor Documentation

OnlineSpliceFrames()

OnlineSpliceFrames ( const OnlineSpliceOptions &  opts, OnlineFeatureInterface *  src  )

inline

Definition at line 481 of file online-feature.h.

                                                 :
      left_context_(opts.left_context), right_context_(opts.right_context),
      src_(src) { }

Member Function Documentation

Dim()

virtual int32 Dim ( ) const

inlinevirtual

Implements OnlineFeatureInterface.

Definition at line 463 of file online-feature.h.

                            {
    return src_->Dim() * (1 + left_context_ + right_context_);
  }

FrameShiftInSeconds()

virtual BaseFloat FrameShiftInSeconds ( ) const

inlinevirtual

Implements OnlineFeatureInterface.

Definition at line 470 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 504 of file online-feature.cc.

References OnlineFeatureInterface::Dim(), VectorBase< Real >::Dim(), OnlineFeatureInterface::GetFrame(), KALDI_ASSERT, rnnlm::n, OnlineFeatureInterface::NumFramesReady(), OnlineCmvn::NumFramesReady(), and OnlineCmvn::src_.

                                                                          {
  KALDI_ASSERT(left_context_ >= 0 && right_context_ >= 0);
  KALDI_ASSERT(frame >= 0 && frame < NumFramesReady());
  int32 dim_in = src_->Dim();
  KALDI_ASSERT(feat->Dim() == dim_in * (1 + left_context_ + right_context_));
  int32 T = src_->NumFramesReady();
  for (int32 t2 = frame - left_context_; t2 <= frame + right_context_; t2++) {
    int32 t2_limited = t2;
    if (t2_limited < 0) t2_limited = 0;
    if (t2_limited >= T) t2_limited = T - 1;
    int32 n = t2 - (frame - left_context_);  // 0 for left-most frame,
                                             // increases to the right.
    SubVector<BaseFloat> part(*feat, n * dim_in, dim_in);
    src_->GetFrame(t2_limited, &part);
  }
}

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 467 of file online-feature.h.

                                              {
    return src_->IsLastFrame(frame);
  }

NumFramesReady()

int32 NumFramesReady ( ) const

virtual

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 496 of file online-feature.cc.

References OnlineFeatureInterface::IsLastFrame(), OnlineFeatureInterface::NumFramesReady(), and OnlineCmvn::src_.

                                               {
  int32 num_frames = src_->NumFramesReady();
  if (num_frames > 0 && src_->IsLastFrame(num_frames - 1))
    return num_frames;
  else
    return std::max<int32>(0, num_frames - right_context_);
}

Member Data Documentation

left_context_

int32 left_context_

private

Definition at line 487 of file online-feature.h.

right_context_

int32 right_context_

private

Definition at line 488 of file online-feature.h.

src_

OnlineFeatureInterface* src_

private

Definition at line 489 of file online-feature.h.

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The documentation for this class was generated from the following files:

• feat/online-feature.h
• feat/online-feature.cc