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   // Creates a chunk of |length| bytes, initialized to zeros.
  23   AudioChunk(size_t length, int bytes_per_sample);
  24   AudioChunk(const uint8* data, size_t length, int bytes_per_sample);
  25
  26   bool IsEmpty() const;
  27   int bytes_per_sample() const { return bytes_per_sample_; }
  28   size_t NumSamples() const;
  29   const std::string& AsString() const;
  30   int16 GetSample16(size_t index) const;
  31   const int16* SamplesData16() const;
  32   uint8* writable_data() { return reinterpret_cast<uint8*>(&data_string_[0]); }
  33
  34  private:
  35   friend class base::RefCountedThreadSafe<AudioChunk>;
  36   ~AudioChunk() {}
  37
  38   std::string data_string_;
  39   const int bytes_per_sample_;
  40
  41   DISALLOW_COPY_AND_ASSIGN(AudioChunk);
  42 };
  43
  44 // Models an audio buffer. The current implementation relies on on-demand
  45 // allocations of AudioChunk(s) (which uses a string as storage).
  46 class AudioBuffer {
  47  public:
  48   explicit AudioBuffer(int bytes_per_sample);
  49   ~AudioBuffer();
  50
  51   // Enqueues a copy of |length| bytes of |data| buffer.
  52   void Enqueue(const uint8* data, size_t length);
  53
  54   // Dequeues, in FIFO order, a single chunk respecting the length of the
  55   // corresponding Enqueue call (in a nutshell: multiple Enqueue calls followed
  56   // by DequeueSingleChunk calls will return the individual chunks without
  57   // merging them).
  58   scoped_refptr<AudioChunk> DequeueSingleChunk();
  59
  60   // Dequeues all previously enqueued chunks, merging them in a single chunk.
  61   scoped_refptr<AudioChunk> DequeueAll();
  62
  63   // Removes and frees all the enqueued chunks.
  64   void Clear();
  65
  66   // Checks whether the buffer is empty.
  67   bool IsEmpty() const;
  68
  69  private:
  70   typedef std::deque<scoped_refptr<AudioChunk> > ChunksContainer;
  71   ChunksContainer chunks_;
  72   const int bytes_per_sample_;
  73
  74   DISALLOW_COPY_AND_ASSIGN(AudioBuffer);
  75 };
  76
  77 }  // namespace content
  78
  79 #endif  // CONTENT_BROWSER_SPEECH_AUDIO_BUFFER_H_