mirror of
https://github.com/mollyim/webrtc.git
synced 2025-05-14 22:30:40 +01:00
f88aa97c52
The video encoder should be informed of incoming LossNotification RTCP messages. Since it is unaware of RTP sequence numbers, or anything else RTP-related, the sequence numbers mentioned in the RTCP message must first be mapped to timestamps, since those are meaningful to the encoder. This CL introduces RtpSequenceNumberMap, which maps RTP sequence numbers to timestamps, while providing: 1. Capping the number of entries. 2. Wrap-around handling. RtpSequenceNumberMap also remembers which packets were first and/or last in the frame. Later CLs will wire this up. Bug: webrtc:10501 Change-Id: Ie0662cdb5706a3bcf63aa2934816a9df88439357 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/130497 Commit-Queue: Elad Alon <eladalon@webrtc.org> Reviewed-by: Danil Chapovalov <danilchap@webrtc.org> Cr-Commit-Position: refs/heads/master@{#27448}
83 lines
2.7 KiB
C++
83 lines
2.7 KiB
C++
/*
|
|
* 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_RTP_SEQUENCE_NUMBER_MAP_H_
|
|
#define MODULES_RTP_RTCP_SOURCE_RTP_SEQUENCE_NUMBER_MAP_H_
|
|
|
|
#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 {
|
|
public:
|
|
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;
|
|
~RtpSequenceNumberMap();
|
|
|
|
void Insert(uint16_t sequence_number, Info info);
|
|
|
|
absl::optional<Info> Get(uint16_t sequence_number) const;
|
|
|
|
size_t AssociationCountForTesting() const;
|
|
|
|
private:
|
|
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
|
|
|
|
#endif // MODULES_RTP_RTCP_SOURCE_RTP_SEQUENCE_NUMBER_MAP_H_
|