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// Copyright 2019 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 CAST_STREAMING_SSRC_H_
#define CAST_STREAMING_SSRC_H_
#include <stdint.h>
namespace openscreen {
namespace cast {
// A Synchronization Source is a 32-bit opaque identifier used in RTP packets
// for identifying the source (or recipient) of a logical sequence of encoded
// audio/video frames. In other words, an audio stream will have one sender SSRC
// and a video stream will have a different sender SSRC.
using Ssrc = uint32_t;
// The "not set" or "null" value for the Ssrc type.
constexpr Ssrc kNullSsrc{0};
// Computes a new SSRC that will be used to uniquely identify an RTP stream. The
// |higher_priority| argument, if true, will generate an SSRC that causes the
// system to use a higher priority when scheduling data transmission. Generally,
// this is set to true for audio streams and false for video streams.
Ssrc GenerateSsrc(bool higher_priority);
// Returns a value indicating how to prioritize data transmission for a stream
// with |ssrc_a| versus a stream with |ssrc_b|:
//
// ret < 0: Stream |ssrc_a| has higher priority.
// ret == 0: Equal priority.
// ret > 0: Stream |ssrc_b| has higher priority.
int ComparePriority(Ssrc ssrc_a, Ssrc ssrc_b);
} // namespace cast
} // namespace openscreen
#endif // CAST_STREAMING_SSRC_H_
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