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// Copyright 2014 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 "base/time/time.h"
#include "media/cast/logging/raw_event_subscriber.h"
namespace media {
namespace cast {
// Estimates receiver time offset based on raw events received.
// In most cases, the sender and receiver run on different time lines.
// In order to convert receiver time back to sender time (or vice versa)
// a certain time offset has to be applied.
// An implementation of this interface listens to raw events to figure out
// the bounds for the offset value (assuming the true offset value is constant
// over the lifetime of a cast session).
// The offset values provided here should be used as follows:
// - Convert from sender to receiver time: add offset value to sender timestamp.
// - Convert from receiver to sender time: subtract offset value from receiver
// timestamp.
class ReceiverTimeOffsetEstimator : public RawEventSubscriber {
~ReceiverTimeOffsetEstimator() override {}
// If bounds are known, assigns |lower_bound| and |upper_bound| with the
// lower bound and upper bound for the offset value, respectively.
// Returns true if bounds are known.
virtual bool GetReceiverOffsetBounds(base::TimeDelta* lower_bound,
base::TimeDelta* upper_bound) = 0;
} // namespace cast
} // namespace media