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Diffstat (limited to 'dom/media/webspeech/recognition/energy_endpointer.h')
| -rw-r--r-- | dom/media/webspeech/recognition/energy_endpointer.h | 180 |
1 files changed, 0 insertions, 180 deletions
diff --git a/dom/media/webspeech/recognition/energy_endpointer.h b/dom/media/webspeech/recognition/energy_endpointer.h deleted file mode 100644 index 2380ecf4b..000000000 --- a/dom/media/webspeech/recognition/energy_endpointer.h +++ /dev/null @@ -1,180 +0,0 @@ -// Copyright (c) 2013 The Chromium Authors. All rights reserved. -// -// Redistribution and use in source and binary forms, with or without -// modification, are permitted provided that the following conditions are -// met: -// -// * Redistributions of source code must retain the above copyright -// notice, this list of conditions and the following disclaimer. -// * Redistributions in binary form must reproduce the above -// copyright notice, this list of conditions and the following disclaimer -// in the documentation and/or other materials provided with the -// distribution. -// * Neither the name of Google Inc. nor the names of its -// contributors may be used to endorse or promote products derived from -// this software without specific prior written permission. -// -// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS -// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT -// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR -// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT -// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, -// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT -// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, -// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY -// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT -// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE -// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. - -// The EnergyEndpointer class finds likely speech onset and offset points. -// -// The implementation described here is about the simplest possible. -// It is based on timings of threshold crossings for overall signal -// RMS. It is suitable for light weight applications. -// -// As written, the basic idea is that one specifies intervals that -// must be occupied by super- and sub-threshold energy levels, and -// defers decisions re onset and offset times until these -// specifications have been met. Three basic intervals are tested: an -// onset window, a speech-on window, and an offset window. We require -// super-threshold to exceed some mimimum total durations in the onset -// and speech-on windows before declaring the speech onset time, and -// we specify a required sub-threshold residency in the offset window -// before declaring speech offset. As the various residency requirements are -// met, the EnergyEndpointer instance assumes various states, and can return the -// ID of these states to the client (see EpStatus below). -// -// The levels of the speech and background noise are continuously updated. It is -// important that the background noise level be estimated initially for -// robustness in noisy conditions. The first frames are assumed to be background -// noise and a fast update rate is used for the noise level. The duration for -// fast update is controlled by the fast_update_dur_ paramter. -// -// If used in noisy conditions, the endpointer should be started and run in the -// EnvironmentEstimation mode, for at least 200ms, before switching to -// UserInputMode. -// Audio feedback contamination can appear in the input audio, if not cut -// out or handled by echo cancellation. Audio feedback can trigger a false -// accept. The false accepts can be ignored by setting -// ep_contamination_rejection_period. - -#ifndef CONTENT_BROWSER_SPEECH_ENDPOINTER_ENERGY_ENDPOINTER_H_ -#define CONTENT_BROWSER_SPEECH_ENDPOINTER_ENERGY_ENDPOINTER_H_ - -#include <vector> - -#include "nsAutoPtr.h" - -#include "energy_endpointer_params.h" - -namespace mozilla { - -// Endpointer status codes -enum EpStatus { - EP_PRE_SPEECH = 10, - EP_POSSIBLE_ONSET, - EP_SPEECH_PRESENT, - EP_POSSIBLE_OFFSET, - EP_POST_SPEECH, -}; - -class EnergyEndpointer { - public: - // The default construction MUST be followed by Init(), before any - // other use can be made of the instance. - EnergyEndpointer(); - virtual ~EnergyEndpointer(); - - void Init(const EnergyEndpointerParams& params); - - // Start the endpointer. This should be called at the beginning of a session. - void StartSession(); - - // Stop the endpointer. - void EndSession(); - - // Start environment estimation. Audio will be used for environment estimation - // i.e. noise level estimation. - void SetEnvironmentEstimationMode(); - - // Start user input. This should be called when the user indicates start of - // input, e.g. by pressing a button. - void SetUserInputMode(); - - // Computes the next input frame and modifies EnergyEndpointer status as - // appropriate based on the computation. - void ProcessAudioFrame(int64_t time_us, - const int16_t* samples, int num_samples, - float* rms_out); - - // Returns the current state of the EnergyEndpointer and the time - // corresponding to the most recently computed frame. - EpStatus Status(int64_t* status_time_us) const; - - bool estimating_environment() const { - return estimating_environment_; - } - - // Returns estimated noise level in dB. - float GetNoiseLevelDb() const; - - private: - class HistoryRing; - - // Resets the endpointer internal state. If reset_threshold is true, the - // state will be reset completely, including adaptive thresholds and the - // removal of all history information. - void Restart(bool reset_threshold); - - // Update internal speech and noise levels. - void UpdateLevels(float rms); - - // Returns the number of frames (or frame number) corresponding to - // the 'time' (in seconds). - int TimeToFrame(float time) const; - - EpStatus status_; // The current state of this instance. - float offset_confirm_dur_sec_; // max on time allowed to confirm POST_SPEECH - int64_t endpointer_time_us_; // Time of the most recently received audio frame. - int64_t fast_update_frames_; // Number of frames for initial level adaptation. - int64_t frame_counter_; // Number of frames seen. Used for initial adaptation. - float max_window_dur_; // Largest search window size (seconds) - float sample_rate_; // Sampling rate. - - // Ring buffers to hold the speech activity history. - nsAutoPtr<HistoryRing> history_; - - // Configuration parameters. - EnergyEndpointerParams params_; - - // RMS which must be exceeded to conclude frame is speech. - float decision_threshold_; - - // Flag to indicate that audio should be used to estimate environment, prior - // to receiving user input. - bool estimating_environment_; - - // Estimate of the background noise level. Used externally for UI feedback. - float noise_level_; - - // An adaptive threshold used to update decision_threshold_ when appropriate. - float rms_adapt_; - - // Start lag corresponds to the highest fundamental frequency. - int start_lag_; - - // End lag corresponds to the lowest fundamental frequency. - int end_lag_; - - // Time when mode switched from environment estimation to user input. This - // is used to time forced rejection of audio feedback contamination. - int64_t user_input_start_time_us_; - - // prevent copy constructor and assignment - EnergyEndpointer(const EnergyEndpointer&); - void operator=(const EnergyEndpointer&); -}; - -} // namespace mozilla - -#endif // CONTENT_BROWSER_SPEECH_ENDPOINTER_ENERGY_ENDPOINTER_H_ |