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