| // Copyright 2016 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef COBALT_MEDIA_BASE_AUDIO_PUSH_FIFO_H_ |
| #define COBALT_MEDIA_BASE_AUDIO_PUSH_FIFO_H_ |
| |
| #include <memory> |
| |
| #include "base/basictypes.h" |
| #include "base/callback.h" |
| #include "cobalt/media/base/audio_bus.h" |
| #include "cobalt/media/base/media_export.h" |
| |
| namespace cobalt { |
| namespace media { |
| |
| // Yet another FIFO for audio data that re-buffers audio to a desired buffer |
| // size. Unlike AudioFifo and AudioBlockFifo, this FIFO cannot overflow: The |
| // client is required to provide a callback that is called synchronously during |
| // a push whenever enough data becomes available. This implementation |
| // eliminates redundant memory copies when the input buffer size always matches |
| // the desired buffer size. |
| class MEDIA_EXPORT AudioPushFifo final { |
| public: |
| // Called synchronously zero, one, or multiple times during a call to Push() |
| // to deliver re-buffered audio. |frame_delay| refers to the position of the |
| // first frame in |output| relative to the first frame in the Push() call. If |
| // negative, this indicates the output contains some data from a prior call to |
| // Push(). If zero or positive, the output contains data from the current |
| // call to Push(). Clients can use this to adjust timestamps. |
| using OutputCallback = |
| base::Callback<void(const AudioBus& output_bus, int frame_delay)>; |
| |
| // Creates a new AudioPushFifo which delivers re-buffered audio by running |
| // |callback|. |
| explicit AudioPushFifo(const OutputCallback& callback); |
| |
| ~AudioPushFifo(); |
| |
| // Returns the number of frames in each AudioBus delivered to the |
| // OutputCallback. |
| int frames_per_buffer() const { return frames_per_buffer_; } |
| |
| // Must be called at least once before the first call to Push(). May be |
| // called later (e.g., to support an audio format change). |
| void Reset(int frames_per_buffer); |
| |
| // Pushes all audio channel data from |input_bus| through the FIFO. This will |
| // result in zero, one, or multiple synchronous calls to the OutputCallback |
| // provided in the constructor. If the |input_bus| has a different number of |
| // channels than the prior Push() call, any currently-queued frames will be |
| // dropped. |
| void Push(const AudioBus& input_bus); |
| |
| // Flushes any enqueued frames by invoking the OutputCallback with those |
| // frames plus padded zero samples. If there are no frames currently |
| // enqueued, OutputCallback is not run. |
| void Flush(); |
| |
| private: |
| const OutputCallback callback_; |
| |
| int frames_per_buffer_; |
| |
| // Queue of frames pending for delivery. |
| std::unique_ptr<AudioBus> audio_queue_; |
| int queued_frames_; |
| |
| DISALLOW_COPY_AND_ASSIGN(AudioPushFifo); |
| }; |
| |
| } // namespace media |
| } // namespace cobalt |
| |
| #endif // COBALT_MEDIA_BASE_AUDIO_PUSH_FIFO_H_ |