blob: 8a036c25a47fb62b6283c3c57524e839a19b583a [file] [log] [blame]
* 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.
#include <cstddef>
#include <cstdint>
#include <deque>
#include "absl/types/optional.h"
namespace webrtc {
// Records the association of RTP sequence numbers to timestamps and to whether
// the packet was first and/or last in the frame.
// 1. Limits number of entries. Whenever `max_entries` is about to be exceeded,
// the size is reduced by approximately 25%.
// 2. RTP sequence numbers wrap around relatively infrequently.
// This class therefore only remembers at most the last 2^15 RTP packets,
// so that the newest packet's sequence number is still AheadOf the oldest
// packet's sequence number.
// 3. Media frames are sometimes split into several RTP packets.
// In such a case, Insert() is expected to be called once for each packet.
// The timestamp is not expected to change between those calls.
class RtpSequenceNumberMap final {
struct Info final {
Info(uint32_t timestamp, bool is_first, bool is_last)
: timestamp(timestamp), is_first(is_first), is_last(is_last) {}
friend bool operator==(const Info& lhs, const Info& rhs) {
return lhs.timestamp == rhs.timestamp && lhs.is_first == rhs.is_first &&
lhs.is_last == rhs.is_last;
uint32_t timestamp;
bool is_first;
bool is_last;
explicit RtpSequenceNumberMap(size_t max_entries);
RtpSequenceNumberMap(const RtpSequenceNumberMap& other) = delete;
RtpSequenceNumberMap& operator=(const RtpSequenceNumberMap& other) = delete;
void InsertPacket(uint16_t sequence_number, Info info);
void InsertFrame(uint16_t first_sequence_number,
size_t packet_count,
uint32_t timestamp);
absl::optional<Info> Get(uint16_t sequence_number) const;
size_t AssociationCountForTesting() const;
struct Association {
explicit Association(uint16_t sequence_number)
: Association(sequence_number, Info(0, false, false)) {}
Association(uint16_t sequence_number, Info info)
: sequence_number(sequence_number), info(info) {}
uint16_t sequence_number;
Info info;
const size_t max_entries_;
// The non-transitivity of AheadOf() would be problematic with a map,
// so we use a deque instead.
std::deque<Association> associations_;
} // namespace webrtc