79 lines
3.2 KiB
C++
79 lines
3.2 KiB
C++
// Copyright 2015 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_CONSTANTS_H_
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#define CAST_STREAMING_CONSTANTS_H_
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////////////////////////////////////////////////////////////////////////////////
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// NOTE: This file should only contain constants that are reasonably globally
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// used (i.e., by many modules, and in all or nearly all subdirs). Do NOT add
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// non-POD constants, functions, interfaces, or any logic to this module.
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////////////////////////////////////////////////////////////////////////////////
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#include <chrono>
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#include <ratio>
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namespace openscreen {
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namespace cast {
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// Default target playout delay. The playout delay is the window of time between
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// capture from the source until presentation at the receiver.
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constexpr std::chrono::milliseconds kDefaultTargetPlayoutDelay(400);
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// Default UDP port, bound at the Receiver, for Cast Streaming. An
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// implementation is required to use the port specified by the Receiver in its
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// ANSWER control message, which may or may not match this port number here.
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constexpr int kDefaultCastStreamingPort = 2344;
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// Default TCP port, bound at the TLS server socket level, for Cast Streaming.
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// An implementation must use the port specified in the DNS-SD published record
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// for connecting over TLS, which may or may not match this port number here.
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constexpr int kDefaultCastPort = 8010;
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// Target number of milliseconds between the sending of RTCP reports. Both
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// senders and receivers regularly send RTCP reports to their peer.
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constexpr std::chrono::milliseconds kRtcpReportInterval(500);
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// This is an important system-wide constant. This limits how much history
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// the implementation must retain in order to process the acknowledgements of
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// past frames.
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//
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// This value is carefully choosen such that it fits in the 8-bits range for
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// frame IDs. It is also less than half of the full 8-bits range such that
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// logic can handle wrap around and compare two frame IDs meaningfully.
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constexpr int kMaxUnackedFrames = 120;
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// The network must support a packet size of at least this many bytes.
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constexpr int kRequiredNetworkPacketSize = 256;
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// The spec declares RTP timestamps must always have a timebase of 90000 ticks
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// per second for video.
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constexpr int kRtpVideoTimebase = 90000;
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// Minimum resolution is 320x240.
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constexpr int kMinVideoHeight = 240;
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constexpr int kMinVideoWidth = 320;
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// The default frame rate for capture options is 30FPS.
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constexpr int kDefaultFrameRate = 30;
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// The default audio sample rate is 48kHz, slightly higher than standard
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// consumer audio.
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constexpr int kDefaultAudioSampleRate = 48000;
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// The default audio number of channels is set to stereo.
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constexpr int kDefaultAudioChannels = 2;
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// Codecs known and understood by cast senders and receivers. Note: receivers
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// are required to implement the following codecs to be Cast V2 compliant: H264,
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// VP8, AAC, Opus. Senders have to implement at least one codec for audio and
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// video to start a session.
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enum class AudioCodec { kAac, kOpus };
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enum class VideoCodec { kH264, kVp8, kHevc, kVp9 };
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} // namespace cast
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} // namespace openscreen
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#endif // CAST_STREAMING_CONSTANTS_H_
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