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// 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.
#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 {
// 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);
// 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();
const OutputCallback callback_;
int frames_per_buffer_;
// Queue of frames pending for delivery.
std::unique_ptr<AudioBus> audio_queue_;
int queued_frames_;
} // namespace media
} // namespace cobalt