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1 // Copyright (c) 2012 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_RECOGNITION_ENGINE_H_ | |
6 #define CONTENT_BROWSER_SPEECH_SPEECH_RECOGNITION_ENGINE_H_ | |
7 #pragma once | |
8 | |
9 #include <string> | |
10 #include <vector> | |
11 | |
12 #include "base/basictypes.h" | |
13 #include "content/public/common/speech_recognition_result.h" | |
14 | |
15 namespace content { | |
16 struct SpeechRecognitionResult; | |
17 struct SpeechRecognitionError; | |
18 } | |
19 | |
20 namespace speech { | |
21 | |
22 class AudioChunk; | |
23 | |
24 // This interface models the basic contract that a speech recognition engine, | |
25 // either working locally or relying on a remote web-service, must obey. | |
26 // The expected call sequence for exported methods is: | |
27 // StartRecognition Mandatory at beginning of SR. | |
28 // TakeAudioChunk For every audio chunk pushed. | |
29 // AudioChunksEnded Finalize the audio stream (omitted in case of errors). | |
30 // EndRecognition Mandatory at end of SR (even on errors). | |
31 // No delegate callback is allowed before Initialize() or after Cleanup(). | |
32 class SpeechRecognitionEngine { | |
33 public: | |
34 // Interface for receiving callbacks from this object. | |
35 class Delegate { | |
36 public: | |
37 // Called whenever a result is retrieved. It might be issued several times, | |
38 // (e.g., in the case of continuous speech recognition engine | |
39 // implementations). | |
40 virtual void OnSpeechRecognitionEngineResult( | |
41 const content::SpeechRecognitionResult& result) = 0; | |
42 virtual void OnSpeechRecognitionEngineError( | |
Satish
2012/03/22 12:03:28
also add a comment mentioning whether recognition
Primiano Tucci (use gerrit)
2012/03/22 12:39:29
It was described a few lines above. BTW I added al
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43 const content::SpeechRecognitionError& error) = 0; | |
44 | |
45 protected: | |
46 virtual ~Delegate() {} | |
47 }; | |
48 | |
49 virtual ~SpeechRecognitionEngine() {} | |
50 | |
51 // Called when the speech recognition begins, before any TakeAudioChunk call. | |
52 virtual void StartRecognition() = 0; | |
53 | |
54 // End any recognition activity and don't make any further callback. | |
55 // No further TakeAudioChunk nor AudioChunksEnded are allowed after this. | |
56 virtual void EndRecognition() = 0; | |
57 | |
58 // Push a chunk of uncompressed audio data, where the chunk length agrees with | |
59 // GetDesiredAudioChunkDurationMs(). | |
60 virtual void TakeAudioChunk(const AudioChunk& data) = 0; | |
61 | |
62 // Notifies the engine that audio capture has completed and no more chunks | |
63 // will be pushed. The engine, however, can still provide further results | |
64 // using the audio chunks collected so far. | |
65 virtual void AudioChunksEnded() = 0; | |
66 | |
67 // Checks wheter recognition of pushed audio data is pending. | |
68 virtual bool IsRecognitionPending() const = 0; | |
69 | |
70 // Retrieves the desired duration, in milliseconds, of pushed AudioChunk(s). | |
71 virtual int GetDesiredAudioChunkDurationMs() const = 0; | |
72 | |
73 // set_delegate detached from constructor for lazy dependency injection. | |
74 void set_delegate(Delegate* delegate) { delegate_ = delegate; } | |
75 | |
76 protected: | |
77 Delegate* delegate() const { return delegate_; } | |
78 | |
79 private: | |
80 Delegate* delegate_; | |
81 }; | |
82 | |
83 // This typedef is to workaround the issue with certain versions of | |
84 // Visual Studio where it gets confused between multiple Delegate | |
85 // classes and gives a C2500 error. (I saw this error on the try bots - | |
86 // the workaround was not needed for my machine). | |
87 typedef SpeechRecognitionEngine::Delegate SpeechRecognitionEngineDelegate; | |
88 | |
89 } // namespace speech | |
90 | |
91 #endif // CONTENT_BROWSER_SPEECH_SPEECH_RECOGNITION_ENGINE_H_ | |
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