content/browser/speech/audio_buffer.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_BUFFER_H_
   6 #define CONTENT_BROWSER_SPEECH_AUDIO_BUFFER_H_
   7 #pragma once
   8
   9 #include <deque>
  10 #include <string>
  11
  12 #include "base/basictypes.h"
  13 #include "base/memory/ref_counted.h"
  14 #include "content/common/content_export.h"
  15
  16 namespace speech {
  17
  18 // Models a chunk derived from an AudioBuffer.
  19 class CONTENT_EXPORT AudioChunk :
  20     public base::RefCountedThreadSafe<AudioChunk> {
  21  public:
  22   explicit AudioChunk(int bytes_per_sample);
  23   AudioChunk(const uint8* data, size_t length, int bytes_per_sample);
  24
  25   bool IsEmpty() const;
  26   int bytes_per_sample() const { return bytes_per_sample_; }
  27   size_t NumSamples() const;
  28   const std::string& AsString() const;
  29   int16 GetSample16(size_t index) const;
  30   const int16* SamplesData16() const;
  31   friend class AudioBuffer;
  32
  33  private:
  34   ~AudioChunk() {}
  35   friend class base::RefCountedThreadSafe<AudioChunk>;
  36
  37   std::string data_string_;
  38   int bytes_per_sample_;
  39
  40   DISALLOW_COPY_AND_ASSIGN(AudioChunk);
  41 };
  42
  43 // Models an audio buffer. The current implementation relies on on-demand
  44 // allocations of AudioChunk(s) (which uses a string as storage).
  45 class AudioBuffer {
  46  public:
  47   explicit AudioBuffer(int bytes_per_sample);
  48   ~AudioBuffer();
  49
  50   // Enqueues a copy of |length| bytes of |data| buffer.
  51   void Enqueue(const uint8* data, size_t length);
  52
  53   // Dequeues, in FIFO order, a single chunk respecting the length of the
  54   // corresponding Enqueue call (in a nutshell: multiple Enqueue calls followed
  55   // by Dequeue calls will return the individual chunks without merging them).
  56   scoped_refptr<AudioChunk> DequeueSingleChunk();
  57
  58   // Dequeues all previously enqueued chunks, merging them in a single chunk.
  59   scoped_refptr<AudioChunk> DequeueAll();
  60
  61   // Removes and frees all the enqueued chunks.
  62   void Clear();
  63
  64   // Checks whether the buffer is empty.
  65   bool IsEmpty() const;
  66
  67  private:
  68   typedef std::deque<scoped_refptr<AudioChunk> > ChunksContainer;
  69   ChunksContainer chunks_;
  70   int bytes_per_sample_;
  71
  72   DISALLOW_COPY_AND_ASSIGN(AudioBuffer);
  73 };
  74
  75 }  // namespace speech
  76
  77 #endif  // CONTENT_BROWSER_SPEECH_AUDIO_BUFFER_H_