chromium/media/base/audio_shifter.h

// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MEDIA_BASE_AUDIO_SHIFTER_H_
#define MEDIA_BASE_AUDIO_SHIFTER_H_

#include <stddef.h>

#include <memory>

#include "base/containers/circular_deque.h"
#include "base/time/time.h"
#include "media/base/media_export.h"
#include "media/base/multi_channel_resampler.h"

namespace media {

class AudioBus;
class ClockSmoother;

// This class works like a buffer between a push based audio source
// and a pull-based audio sink. The source and sink should operate
// at nominally the same rate, but since they may run on different
// hardware clocks, the rate may differ a little. If left unchecked,
// this difference will first cause lip sync issues between audio
// and video and eventually it will cause buffer overruns/underruns.
// This class solves all that by dynamically resampling the audio
// so that both input and output sources are happy.
//
// A note about TimeTicks. The playout_time specified in Push and
// Pull calls must come from the same timeline. That timeline can
// be anything you choose as it is never compared to any real-world
// clocks, but they must come from the same clock. Specifically,
// specifying samples / rate as the playout time in Push() or Pull()
// will NOT work.
//
class MEDIA_EXPORT AudioShifter { … };

}  // namespace media

#endif  // MEDIA_BASE_AUDIO_SHIFTER_H_