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authorDeterminant <[email protected]>2015-08-14 11:51:42 +0800
committerDeterminant <[email protected]>2015-08-14 11:51:42 +0800
commit96a32415ab43377cf1575bd3f4f2980f58028209 (patch)
tree30a2d92d73e8f40ac87b79f6f56e227bfc4eea6e /kaldi_io/src/kaldi/itf/online-feature-itf.h
parentc177a7549bd90670af4b29fa813ddea32cfe0f78 (diff)
add implementation for kaldi io (by ymz)
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+// itf/online-feature-itf.h
+
+// Copyright 2013 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_ITF_ONLINE_FEATURE_ITF_H_
+#define KALDI_ITF_ONLINE_FEATURE_ITF_H_ 1
+#include "base/kaldi-common.h"
+#include "matrix/matrix-lib.h"
+
+namespace kaldi {
+/// @ingroup Interfaces
+/// @{
+
+/**
+ OnlineFeatureInterface is an interface for online feature processing (it is
+ also usable in the offline setting, but currently we're not using it for
+ that). This is for use in the online2/ directory, and it supersedes the
+ interface in ../online/online-feat-input.h. We have a slighty different
+ model that puts more control in the hands of the calling thread, and won't
+ involve waiting on semaphores in the decoding thread.
+
+ This interface only specifies how the object *outputs* the features.
+ How it obtains the features, e.g. from a previous object or objects of type
+ OnlineFeatureInterface, is not specified in the interface and you will
+ likely define new constructors or methods in the derived type to do that.
+
+ You should appreciate that this interface is designed to allow random
+ access to features, as long as they are ready. That is, the user
+ can call GetFrame for any frame less than NumFramesReady(), and when
+ implementing a child class you must not make assumptions about the
+ order in which the user makes these calls.
+*/
+
+class OnlineFeatureInterface {
+ public:
+ virtual int32 Dim() const = 0; /// 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.
+ virtual int32 NumFramesReady() const = 0;
+
+ /// 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).
+ virtual bool IsLastFrame(int32 frame) const = 0;
+
+ /// 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.
+ virtual void GetFrame(int32 frame, VectorBase<BaseFloat> *feat) = 0;
+
+ /// Virtual destructor. Note: constructors that take another member of
+ /// type OnlineFeatureInterface are not expected to take ownership of
+ /// that pointer; the caller needs to keep track of that manually.
+ virtual ~OnlineFeatureInterface() { }
+};
+
+
+/// Add a virtual class for "source" features such as MFCC or PLP or pitch
+/// features.
+class OnlineBaseFeature: public OnlineFeatureInterface {
+ public:
+ /// This would be called from the application, when you get more wave data.
+ /// Note: the sampling_rate is typically only provided so the code can assert
+ /// that it matches the sampling rate expected in the options.
+ virtual void AcceptWaveform(BaseFloat sampling_rate,
+ const VectorBase<BaseFloat> &waveform) = 0;
+
+ /// InputFinished() tells the class you won't be providing any
+ /// more waveform. This will help flush out the last few frames
+ /// of delta or LDA features (it will typically affect the return value
+ /// of IsLastFrame.
+ virtual void InputFinished() = 0;
+};
+
+
+/// @}
+} // namespace Kaldi
+
+#endif // KALDI_ITF_ONLINE_FEATURE_ITF_H_