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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_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_
     77