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* LossNotificationController is the class that decides when to issue LossNotification RTCP messages. * RtpRtcp handles the technicalities of producing RTCP messages. Bug: webrtc:10336 Change-Id: I292536257a984ca85d21d9cfa38e7ff2569cbb39 Reviewed-on: https://webrtc-review.googlesource.com/c/124123 Reviewed-by: Erik Språng <sprang@webrtc.org> Reviewed-by: Danil Chapovalov <danilchap@webrtc.org> Commit-Queue: Elad Alon <eladalon@webrtc.org> Cr-Commit-Position: refs/heads/master@{#26840}
133 lines
4.7 KiB
C++
133 lines
4.7 KiB
C++
/*
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* Copyright (c) 2019 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "modules/rtp_rtcp/source/rtcp_packet/loss_notification.h"
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#include "modules/rtp_rtcp/source/byte_io.h"
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#include "modules/rtp_rtcp/source/rtcp_packet/common_header.h"
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#include "rtc_base/checks.h"
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#include "rtc_base/logging.h"
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namespace webrtc {
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namespace rtcp {
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// Loss Notification
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// -----------------
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// 0 1 2 3
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// 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// |V=2|P| FMT=15 | PT=206 | length |
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// +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
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// 0 | SSRC of packet sender |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// 4 | SSRC of media source |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// 8 | Unique identifier 'L' 'N' 'T' 'F' |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// 12 | Last Decoded Sequence Number | Last Received SeqNum Delta |D|
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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LossNotification::LossNotification()
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: last_decoded_(0), last_received_(0), decodability_flag_(false) {}
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LossNotification::LossNotification(uint16_t last_decoded,
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uint16_t last_received,
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bool decodability_flag)
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: last_decoded_(last_decoded),
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last_received_(last_received),
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decodability_flag_(decodability_flag) {}
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LossNotification::LossNotification(const LossNotification& rhs) = default;
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LossNotification::~LossNotification() = default;
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size_t LossNotification::BlockLength() const {
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return kHeaderLength + kCommonFeedbackLength + kLossNotificationPayloadLength;
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}
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bool LossNotification::Create(uint8_t* packet,
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size_t* index,
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size_t max_length,
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PacketReadyCallback callback) const {
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while (*index + BlockLength() > max_length) {
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if (!OnBufferFull(packet, index, callback))
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return false;
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}
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const size_t index_end = *index + BlockLength();
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// Note: |index| updated by the function below.
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CreateHeader(Psfb::kAfbMessageType, kPacketType, HeaderLength(), packet,
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index);
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CreateCommonFeedback(packet + *index);
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*index += kCommonFeedbackLength;
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ByteWriter<uint32_t>::WriteBigEndian(packet + *index, kUniqueIdentifier);
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*index += sizeof(uint32_t);
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ByteWriter<uint16_t>::WriteBigEndian(packet + *index, last_decoded_);
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*index += sizeof(uint16_t);
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const uint16_t last_received_delta = last_received_ - last_decoded_;
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RTC_DCHECK_LE(last_received_delta, 0x7fff);
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const uint16_t last_received_delta_and_decodability =
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(last_received_delta << 1) | (decodability_flag_ ? 0x0001 : 0x0000);
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ByteWriter<uint16_t>::WriteBigEndian(packet + *index,
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last_received_delta_and_decodability);
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*index += sizeof(uint16_t);
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RTC_DCHECK_EQ(index_end, *index);
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return true;
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}
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bool LossNotification::Parse(const CommonHeader& packet) {
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RTC_DCHECK_EQ(packet.type(), kPacketType);
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RTC_DCHECK_EQ(packet.fmt(), Psfb::kAfbMessageType);
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if (packet.payload_size_bytes() <
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kCommonFeedbackLength + kLossNotificationPayloadLength) {
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return false;
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}
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const uint8_t* const payload = packet.payload();
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if (ByteReader<uint32_t>::ReadBigEndian(&payload[8]) != kUniqueIdentifier) {
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return false;
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}
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ParseCommonFeedback(payload);
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last_decoded_ = ByteReader<uint16_t>::ReadBigEndian(&payload[12]);
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const uint16_t last_received_delta_and_decodability =
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ByteReader<uint16_t>::ReadBigEndian(&payload[14]);
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last_received_ = last_decoded_ + (last_received_delta_and_decodability >> 1);
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decodability_flag_ = (last_received_delta_and_decodability & 0x0001);
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return true;
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}
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bool LossNotification::Set(uint16_t last_decoded,
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uint16_t last_received,
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bool decodability_flag) {
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const uint16_t delta = last_received - last_decoded;
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if (delta > 0x7fff) {
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return false;
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}
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last_received_ = last_received;
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last_decoded_ = last_decoded;
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decodability_flag_ = decodability_flag;
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return true;
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}
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} // namespace rtcp
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} // namespace webrtc
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