content/browser/speech/audio_encoder.h

   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 #pragma once
   8
   9 #include <list>
  10 #include <string>
  11
  12 #include "base/basictypes.h"
  13 #include "base/memory/ref_counted.h"
  14 #include "content/browser/speech/audio_buffer.h"
  15
  16 namespace speech {
  17 class AudioChunk;
  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 speech
  59
  60 #endif  // CONTENT_BROWSER_SPEECH_AUDIO_ENCODER_H_