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