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      1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CONTENT_BROWSER_SPEECH_SPEECH_RECOGNIZER_IMPL_H_
      6 #define CONTENT_BROWSER_SPEECH_SPEECH_RECOGNIZER_IMPL_H_
      7 
      8 #include "base/basictypes.h"
      9 #include "base/memory/scoped_ptr.h"
     10 #include "content/browser/speech/endpointer/endpointer.h"
     11 #include "content/browser/speech/speech_recognition_engine.h"
     12 #include "content/browser/speech/speech_recognizer.h"
     13 #include "content/public/common/speech_recognition_error.h"
     14 #include "content/public/common/speech_recognition_result.h"
     15 #include "media/audio/audio_input_controller.h"
     16 #include "net/url_request/url_request_context_getter.h"
     17 
     18 namespace media {
     19 class AudioBus;
     20 class AudioManager;
     21 }
     22 
     23 namespace content {
     24 
     25 class SpeechRecognitionEventListener;
     26 
     27 // Handles speech recognition for a session (identified by |session_id|), taking
     28 // care of audio capture, silence detection/endpointer and interaction with the
     29 // SpeechRecognitionEngine.
     30 class CONTENT_EXPORT SpeechRecognizerImpl
     31     : public SpeechRecognizer,
     32       public media::AudioInputController::EventHandler,
     33       public NON_EXPORTED_BASE(SpeechRecognitionEngineDelegate) {
     34  public:
     35   static const int kAudioSampleRate;
     36   static const media::ChannelLayout kChannelLayout;
     37   static const int kNumBitsPerAudioSample;
     38   static const int kNoSpeechTimeoutMs;
     39   static const int kEndpointerEstimationTimeMs;
     40 
     41   static void SetAudioManagerForTesting(media::AudioManager* audio_manager);
     42 
     43   SpeechRecognizerImpl(SpeechRecognitionEventListener* listener,
     44                        int session_id,
     45                        bool continuous,
     46                        bool provisional_results,
     47                        SpeechRecognitionEngine* engine);
     48 
     49   virtual void StartRecognition(const std::string& device_id) OVERRIDE;
     50   virtual void AbortRecognition() OVERRIDE;
     51   virtual void StopAudioCapture() OVERRIDE;
     52   virtual bool IsActive() const OVERRIDE;
     53   virtual bool IsCapturingAudio() const OVERRIDE;
     54   const SpeechRecognitionEngine& recognition_engine() const;
     55 
     56  private:
     57   friend class SpeechRecognizerTest;
     58 
     59   enum FSMState {
     60     STATE_IDLE = 0,
     61     STATE_STARTING,
     62     STATE_ESTIMATING_ENVIRONMENT,
     63     STATE_WAITING_FOR_SPEECH,
     64     STATE_RECOGNIZING,
     65     STATE_WAITING_FINAL_RESULT,
     66     STATE_ENDED,
     67     STATE_MAX_VALUE = STATE_ENDED
     68   };
     69 
     70   enum FSMEvent {
     71     EVENT_ABORT = 0,
     72     EVENT_START,
     73     EVENT_STOP_CAPTURE,
     74     EVENT_AUDIO_DATA,
     75     EVENT_ENGINE_RESULT,
     76     EVENT_ENGINE_ERROR,
     77     EVENT_AUDIO_ERROR,
     78     EVENT_MAX_VALUE = EVENT_AUDIO_ERROR
     79   };
     80 
     81   struct FSMEventArgs {
     82     explicit FSMEventArgs(FSMEvent event_value);
     83     ~FSMEventArgs();
     84 
     85     FSMEvent event;
     86     scoped_refptr<AudioChunk> audio_data;
     87     SpeechRecognitionResults engine_results;
     88     SpeechRecognitionError engine_error;
     89   };
     90 
     91   virtual ~SpeechRecognizerImpl();
     92 
     93   // Entry point for pushing any new external event into the recognizer FSM.
     94   void DispatchEvent(const FSMEventArgs& event_args);
     95 
     96   // Defines the behavior of the recognizer FSM, selecting the appropriate
     97   // transition according to the current state and event.
     98   FSMState ExecuteTransitionAndGetNextState(const FSMEventArgs& args);
     99 
    100   // Process a new audio chunk in the audio pipeline (endpointer, vumeter, etc).
    101   void ProcessAudioPipeline(const AudioChunk& raw_audio);
    102 
    103   // The methods below handle transitions of the recognizer FSM.
    104   FSMState StartRecording(const FSMEventArgs& event_args);
    105   FSMState StartRecognitionEngine(const FSMEventArgs& event_args);
    106   FSMState WaitEnvironmentEstimationCompletion(const FSMEventArgs& event_args);
    107   FSMState DetectUserSpeechOrTimeout(const FSMEventArgs& event_args);
    108   FSMState StopCaptureAndWaitForResult(const FSMEventArgs& event_args);
    109   FSMState ProcessIntermediateResult(const FSMEventArgs& event_args);
    110   FSMState ProcessFinalResult(const FSMEventArgs& event_args);
    111   FSMState AbortSilently(const FSMEventArgs& event_args);
    112   FSMState AbortWithError(const FSMEventArgs& event_args);
    113   FSMState Abort(const SpeechRecognitionError& error);
    114   FSMState DetectEndOfSpeech(const FSMEventArgs& event_args);
    115   FSMState DoNothing(const FSMEventArgs& event_args) const;
    116   FSMState NotFeasible(const FSMEventArgs& event_args);
    117 
    118   // Returns the time span of captured audio samples since the start of capture.
    119   int GetElapsedTimeMs() const;
    120 
    121   // Calculates the input volume to be displayed in the UI, triggering the
    122   // OnAudioLevelsChange event accordingly.
    123   void UpdateSignalAndNoiseLevels(const float& rms, bool clip_detected);
    124 
    125   void CloseAudioControllerAsynchronously();
    126 
    127   // Callback called on IO thread by audio_controller->Close().
    128   void OnAudioClosed(media::AudioInputController*);
    129 
    130   // AudioInputController::EventHandler methods.
    131   virtual void OnCreated(media::AudioInputController* controller) OVERRIDE {}
    132   virtual void OnRecording(media::AudioInputController* controller) OVERRIDE {}
    133   virtual void OnError(media::AudioInputController* controller,
    134       media::AudioInputController::ErrorCode error_code) OVERRIDE;
    135   virtual void OnData(media::AudioInputController* controller,
    136                       const media::AudioBus* data) OVERRIDE;
    137   virtual void OnLog(media::AudioInputController* controller,
    138                      const std::string& message) OVERRIDE {}
    139 
    140   // SpeechRecognitionEngineDelegate methods.
    141   virtual void OnSpeechRecognitionEngineResults(
    142       const SpeechRecognitionResults& results) OVERRIDE;
    143   virtual void OnSpeechRecognitionEngineError(
    144       const SpeechRecognitionError& error) OVERRIDE;
    145 
    146   static media::AudioManager* audio_manager_for_tests_;
    147 
    148   scoped_ptr<SpeechRecognitionEngine> recognition_engine_;
    149   Endpointer endpointer_;
    150   scoped_refptr<media::AudioInputController> audio_controller_;
    151   int num_samples_recorded_;
    152   float audio_level_;
    153   bool is_dispatching_event_;
    154   bool provisional_results_;
    155   FSMState state_;
    156   std::string device_id_;
    157 
    158   class OnDataConverter;
    159 
    160   // Converts data between native input format and a WebSpeech specific
    161   // output format.
    162   scoped_ptr<SpeechRecognizerImpl::OnDataConverter> audio_converter_;
    163 
    164   DISALLOW_COPY_AND_ASSIGN(SpeechRecognizerImpl);
    165 };
    166 
    167 }  // namespace content
    168 
    169 #endif  // CONTENT_BROWSER_SPEECH_SPEECH_RECOGNIZER_IMPL_H_
    170