The Tor Browser: content/media/webspeech/recognition/energy

content/media/webspeech/recognition/energy_endpointer.h@a63d609f5ebe (annotated)

content/media/webspeech/recognition/energy_endpointer.h

Thu, 15 Jan 2015 15:55:04 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 15 Jan 2015 15:55:04 +0100
branch: TOR_BUG_9701
changeset 9: a63d609f5ebe
permissions: -rw-r--r--

Back out 97036ab72558 which inappropriately compared turds to third parties.

 // 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_

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content/media/webspeech/recognition/energy_endpointer.h@a63d609f5ebe (annotated)

content/media/webspeech/recognition/energy_endpointer.h