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/*
* Copyright (c) 2019 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#ifndef MODULES_RTP_RTCP_SOURCE_SOURCE_TRACKER_H_
#define MODULES_RTP_RTCP_SOURCE_SOURCE_TRACKER_H_
#include <cstddef>
#include <cstdint>
#include <list>
#include <optional>
#include <unordered_map>
#include <utility>
#include <vector>
#include "api/rtp_headers.h"
#include "api/rtp_packet_infos.h"
#include "api/transport/rtp/rtp_source.h"
#include "api/units/time_delta.h"
#include "api/units/timestamp.h"
#include "system_wrappers/include/clock.h"
namespace webrtc {
//
// Tracker for `RTCRtpContributingSource` and `RTCRtpSynchronizationSource`:
// - https://w3c.github.io/webrtc-pc/#dom-rtcrtpcontributingsource
// - https://w3c.github.io/webrtc-pc/#dom-rtcrtpsynchronizationsource
//
// This class is thread unsafe.
class SourceTracker {
public:
// Amount of time before the entry associated with an update is removed. See:
// https://w3c.github.io/webrtc-pc/#dom-rtcrtpreceiver-getcontributingsources
static constexpr TimeDelta kTimeout = TimeDelta::Seconds(10);
explicit SourceTracker(Clock* clock);
SourceTracker(const SourceTracker& other) = delete;
SourceTracker(SourceTracker&& other) = delete;
SourceTracker& operator=(const SourceTracker& other) = delete;
SourceTracker& operator=(SourceTracker&& other) = delete;
// Updates the source entries when a frame is delivered to the
// RTCRtpReceiver's MediaStreamTrack.
void OnFrameDelivered(const RtpPacketInfos& packet_infos,
Timestamp delivery_time = Timestamp::MinusInfinity());
// Returns an `RtpSource` for each unique SSRC and CSRC identifier updated in
// the last `kTimeoutMs` milliseconds. Entries appear in reverse chronological
// order (i.e. with the most recently updated entries appearing first).
std::vector<RtpSource> GetSources() const;
private:
struct SourceKey {
SourceKey(RtpSourceType source_type, uint32_t source)
: source_type(source_type), source(source) {}
// Type of `source`.
RtpSourceType source_type;
// CSRC or SSRC identifier of the contributing or synchronization source.
uint32_t source;
};
struct SourceKeyComparator {
bool operator()(const SourceKey& lhs, const SourceKey& rhs) const {
return (lhs.source_type == rhs.source_type) && (lhs.source == rhs.source);
}
};
struct SourceKeyHasher {
size_t operator()(const SourceKey& value) const {
return static_cast<size_t>(value.source_type) +
static_cast<size_t>(value.source) * 11076425802534262905ULL;
}
};
struct SourceEntry {
// Timestamp indicating the most recent time a frame from an RTP packet,
// originating from this source, was delivered to the RTCRtpReceiver's
// MediaStreamTrack. Its reference clock is the outer class's `clock_`.
Timestamp timestamp = Timestamp::MinusInfinity();
// Audio level from an RFC 6464 or RFC 6465 header extension received with
// the most recent packet used to assemble the frame associated with
// `timestamp`. May be absent. Only relevant for audio receivers. See the
// specs for `RTCRtpContributingSource` for more info.
std::optional<uint8_t> audio_level;
// Absolute capture time header extension received or interpolated from the
// most recent packet used to assemble the frame. For more info see
// https://webrtc.org/experiments/rtp-hdrext/abs-capture-time/
std::optional<AbsoluteCaptureTime> absolute_capture_time;
// Clock offset between the local clock and the capturer's clock.
// Do not confuse with `AbsoluteCaptureTime::estimated_capture_clock_offset`
// which instead represents the clock offset between a remote sender and the
// capturer. The following holds:
// Capture's NTP Clock = Local NTP Clock + Local-Capture Clock Offset
std::optional<TimeDelta> local_capture_clock_offset;
// RTP timestamp of the most recent packet used to assemble the frame
// associated with `timestamp`.
uint32_t rtp_timestamp = 0;
};
using SourceList = std::list<std::pair<const SourceKey, SourceEntry>>;
using SourceMap = std::unordered_map<SourceKey,
SourceList::iterator,
SourceKeyHasher,
SourceKeyComparator>;
// Updates an entry by creating it (if it didn't previously exist) and moving
// it to the front of the list. Returns a reference to the entry.
SourceEntry& UpdateEntry(const SourceKey& key);
// Removes entries that have timed out. Marked as "const" so that we can do
// pruning in getters.
void PruneEntries(Timestamp now) const;
Clock* const clock_;
// Entries are stored in reverse chronological order (i.e. with the most
// recently updated entries appearing first). Mutability is needed for timeout
// pruning in const functions.
mutable SourceList list_;
mutable SourceMap map_;
};
} // namespace webrtc
#endif // MODULES_RTP_RTCP_SOURCE_SOURCE_TRACKER_H_
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