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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_AUDIO_ENCODER_H_
      6 #define CONTENT_BROWSER_SPEECH_AUDIO_ENCODER_H_
      7 
      8 #include <list>
      9 #include <string>
     10 
     11 #include "base/basictypes.h"
     12 #include "base/memory/ref_counted.h"
     13 #include "content/browser/speech/audio_buffer.h"
     14 
     15 namespace content{
     16 class AudioChunk;
     17 
     18 // Provides a simple interface to encode raw audio using the various speech
     19 // codecs.
     20 class AudioEncoder {
     21  public:
     22   enum Codec {
     23     CODEC_FLAC,
     24     CODEC_SPEEX,
     25   };
     26 
     27   static AudioEncoder* Create(Codec codec,
     28                               int sampling_rate,
     29                               int bits_per_sample);
     30 
     31   virtual ~AudioEncoder();
     32 
     33   // Encodes |raw audio| to the internal buffer. Use
     34   // |GetEncodedDataAndClear| to read the result after this call or when
     35   // audio capture completes.
     36   virtual void Encode(const AudioChunk& raw_audio) = 0;
     37 
     38   // Finish encoding and flush any pending encoded bits out.
     39   virtual void Flush() = 0;
     40 
     41   // Merges, retrieves and clears all the accumulated encoded audio chunks.
     42   scoped_refptr<AudioChunk> GetEncodedDataAndClear();
     43 
     44   const std::string& mime_type() { return mime_type_; }
     45   int bits_per_sample() { return bits_per_sample_; }
     46 
     47  protected:
     48   AudioEncoder(const std::string& mime_type, int bits_per_sample);
     49   AudioBuffer encoded_audio_buffer_;
     50 
     51  private:
     52   std::string mime_type_;
     53   int bits_per_sample_;
     54 
     55   DISALLOW_COPY_AND_ASSIGN(AudioEncoder);
     56 };
     57 
     58 }  // namespace content
     59 
     60 #endif  // CONTENT_BROWSER_SPEECH_AUDIO_ENCODER_H_
     61