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f8e7ccb967
Create a new RTCP feedback message for reporting the loss and/or non-decodability of video frames, to be used by the upcoming injectable VideoFrameBufferController. The new feedback message should report: 1. The sequence number of the last decoded non-discardable video frame. (TBD: If a multi-packet frame, should it be the sequence number of the first, last, or any of the packets?) 2. The sequence number of the last received RTP packet in the stream. 3. A decodability flag, whose specific meaning depends on the last-received RTP sequence number. The decodability flag is true if and only if all of the frame's dependencies are known to be decodable, and the frame itself is not yet known to be unassemblable. * Clarification #1: In a multi-packet frame, the first packet's dependencies are known, but it is not yet known whether all parts of the current frame will be received. * Clarification #2: In a multi-packet frame, the dependencies would be unknown if the first packet was not received. Then, the packet will be known-unassemblable. Bug: webrtc:10226 Change-Id: I1563c944477e3ed40235e82ab99a439414632aff Reviewed-on: https://webrtc-review.googlesource.com/c/118931 Commit-Queue: Elad Alon <eladalon@webrtc.org> Reviewed-by: Danil Chapovalov <danilchap@webrtc.org> Reviewed-by: Björn Terelius <terelius@webrtc.org> Cr-Commit-Position: refs/heads/master@{#26387}
127 lines
4.5 KiB
C++
127 lines
4.5 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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constexpr uint8_t LossNotification::kFeedbackMessageType;
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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(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(kFeedbackMessageType, 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(), kFeedbackMessageType);
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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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