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| 1 // Copyright 2016 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_PUSH_FIFO_H_ |
| 6 #define MEDIA_BASE_AUDIO_PUSH_FIFO_H_ |
| 7 |
| 8 #include "base/callback.h" |
| 9 #include "base/macros.h" |
| 10 #include "base/memory/scoped_ptr.h" |
| 11 #include "media/base/audio_bus.h" |
| 12 #include "media/base/media_export.h" |
| 13 |
| 14 namespace media { |
| 15 |
| 16 // Yet another FIFO for audio data that re-buffers audio to a desired buffer |
| 17 // size. Unlike AudioFifo and AudioBlockFifo, this FIFO cannot overflow: The |
| 18 // client is required to provide a callback that is called synchronously during |
| 19 // a push whenever enough data becomes available. This implementation |
| 20 // eliminates redundant memory copies when the input buffer size always matches |
| 21 // the desired buffer size. |
| 22 class MEDIA_EXPORT AudioPushFifo final { |
| 23 public: |
| 24 // Called synchronously zero, one, or multiple times during a call to Push() |
| 25 // to deliver re-buffered audio. |frame_delay| refers to the position of the |
| 26 // first frame in |output| relative to the first frame in the Push() call. If |
| 27 // negative, this indicates the output contains some data from a prior call to |
| 28 // Push(). If zero or positive, the output contains data from the current |
| 29 // call to Push(). Clients can use this to adjust timestamps. |
| 30 using OutputCallback = |
| 31 base::Callback<void(const AudioBus& output_bus, int frame_delay)>; |
| 32 |
| 33 // Creates a new AudioPushFifo which delivers re-buffered audio by running |
| 34 // |callback|. |
| 35 explicit AudioPushFifo(const OutputCallback& callback); |
| 36 |
| 37 ~AudioPushFifo(); |
| 38 |
| 39 // Returns the number of frames in each AudioBus delivered to the |
| 40 // OutputCallback. |
| 41 int frames_per_buffer() const { return frames_per_buffer_; } |
| 42 |
| 43 // Must be called at least once before the first call to Push(). May be |
| 44 // called later (e.g., to support an audio format change). |
| 45 void Reset(int frames_per_buffer); |
| 46 |
| 47 // Pushes all audio channel data from |input_bus| through the FIFO. This will |
| 48 // result in zero, one, or multiple synchronous calls to the OutputCallback |
| 49 // provided in the constructor. If the |input_bus| has a different number of |
| 50 // channels than the prior Push() call, any currently-queued frames will be |
| 51 // dropped. |
| 52 void Push(const AudioBus& input_bus); |
| 53 |
| 54 // Flushes any enqueued frames by invoking the OutputCallback with those |
| 55 // frames plus padded zero samples. If there are no frames currently |
| 56 // enqueued, OutputCallback is not run. |
| 57 void Flush(); |
| 58 |
| 59 private: |
| 60 const OutputCallback callback_; |
| 61 |
| 62 int frames_per_buffer_; |
| 63 |
| 64 // Queue of frames pending for delivery. |
| 65 scoped_ptr<AudioBus> audio_queue_; |
| 66 int queued_frames_; |
| 67 |
| 68 DISALLOW_COPY_AND_ASSIGN(AudioPushFifo); |
| 69 }; |
| 70 |
| 71 } // namespace media |
| 72 |
| 73 #endif // MEDIA_BASE_AUDIO_PUSH_FIFO_H_ |
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