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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 MEDIA_BASE_AUDIO_FIFO_H_ |
| 6 #define MEDIA_BASE_AUDIO_FIFO_H_ |
| 7 |
| 8 #include "media/base/audio_bus.h" |
| 9 #include "media/base/media_export.h" |
| 10 |
| 11 namespace media { |
| 12 |
| 13 // First-in first-out container for AudioBus elements. |
| 14 // The maximum number of audio frames in the FIFO is set at construction and |
| 15 // can not be extended dynamically. The allocated memory is utilized as a |
| 16 // ring buffer. |
| 17 class MEDIA_EXPORT AudioFifo { |
| 18 public: |
| 19 // Creates a new AudioFifo and allocates |channels| of length |frames|. |
| 20 AudioFifo(int channels, int frames); |
| 21 virtual ~AudioFifo(); |
| 22 |
| 23 // Pushes all audio channel data from |source| to the FIFO. |
| 24 // Returns false if the allocated space is not sufficient. Partial data is |
| 25 // not written to the FIFO for this overflow case. |
| 26 bool Push(const AudioBus* source); |
| 27 |
| 28 // Consumes |frames_to_consume| audio frames from the FIFO and copies |
| 29 // them to |destination|. |
| 30 // Returns false if the FIFO does not contain |frames_to_consume| frames |
| 31 // or if there is not sufficient space in |destination| to store the frames. |
| 32 bool Consume(AudioBus* destination, int frames_to_consume); |
| 33 |
| 34 // Empties the FIFO without deallocating any memory. |
| 35 void Clear(); |
| 36 |
| 37 // Number of actual audio frames in the FIFO. |
| 38 int frames_in_fifo() const { return frames_in_fifo_; } |
| 39 |
| 40 private: |
| 41 int max_frames() const { return max_frames_in_fifo_; } |
| 42 |
| 43 // The actual FIFO is an audio bus implemented as a ring buffer. |
| 44 scoped_ptr<AudioBus> audio_bus_; |
| 45 |
| 46 // Maximum number of elements the FIFO can contain. |
| 47 // This value is set by |frames| in the constructor. |
| 48 const int max_frames_in_fifo_; |
| 49 |
| 50 // Number of actual elements in the FIFO. |
| 51 int frames_in_fifo_; |
| 52 |
| 53 // Current read position. |
| 54 int read_pos_; |
| 55 |
| 56 // Current write position. |
| 57 int write_pos_; |
| 58 |
| 59 DISALLOW_COPY_AND_ASSIGN(AudioFifo); |
| 60 }; |
| 61 |
| 62 } // namespace media |
| 63 |
| 64 #endif // MEDIA_BASE_AUDIO_FIFO_H_ |
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