1 files changed, 133 insertions, 0 deletions
diff --git a/third_party/libwebrtc/modules/rtp_rtcp/source/rtcp_packet/loss_notification.cc b/third_party/libwebrtc/modules/rtp_rtcp/source/rtcp_packet/loss_notification.cc
new file mode 100644
index 0000000000..0817846f95
--- /dev/null
+++ b/third_party/libwebrtc/modules/rtp_rtcp/source/rtcp_packet/loss_notification.cc
@@ -0,0 +1,133 @@
+/*
+ *  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 "modules/rtp_rtcp/source/rtcp_packet/loss_notification.h"
+
+#include "modules/rtp_rtcp/source/byte_io.h"
+#include "modules/rtp_rtcp/source/rtcp_packet/common_header.h"
+#include "rtc_base/checks.h"
+#include "rtc_base/logging.h"
+
+namespace webrtc {
+namespace rtcp {
+
+// Loss Notification
+// -----------------
+//     0                   1                   2                   3
+//     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
+//    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//    |V=2|P| FMT=15  |   PT=206      |             length            |
+//    +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
+//  0 |                  SSRC of packet sender                        |
+//    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//  4 |                  SSRC of media source                         |
+//    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+//  8 |  Unique identifier 'L' 'N' 'T' 'F'                            |
+//    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+// 12 | Last Decoded Sequence Number  | Last Received SeqNum Delta  |D|
+//    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+LossNotification::LossNotification()
+    : last_decoded_(0), last_received_(0), decodability_flag_(false) {}
+
+LossNotification::LossNotification(uint16_t last_decoded,
+                                   uint16_t last_received,
+                                   bool decodability_flag)
+    : last_decoded_(last_decoded),
+      last_received_(last_received),
+      decodability_flag_(decodability_flag) {}
+
+LossNotification::LossNotification(const LossNotification& rhs) = default;
+
+LossNotification::~LossNotification() = default;
+
+size_t LossNotification::BlockLength() const {
+  return kHeaderLength + kCommonFeedbackLength + kLossNotificationPayloadLength;
+}
+
+bool LossNotification::Create(uint8_t* packet,
+                              size_t* index,
+                              size_t max_length,
+                              PacketReadyCallback callback) const {
+  while (*index + BlockLength() > max_length) {
+    if (!OnBufferFull(packet, index, callback))
+      return false;
+  }
+
+  const size_t index_end = *index + BlockLength();
+
+  // Note: `index` updated by the function below.
+  CreateHeader(Psfb::kAfbMessageType, kPacketType, HeaderLength(), packet,
+               index);
+
+  CreateCommonFeedback(packet + *index);
+  *index += kCommonFeedbackLength;
+
+  ByteWriter<uint32_t>::WriteBigEndian(packet + *index, kUniqueIdentifier);
+  *index += sizeof(uint32_t);
+
+  ByteWriter<uint16_t>::WriteBigEndian(packet + *index, last_decoded_);
+  *index += sizeof(uint16_t);
+
+  const uint16_t last_received_delta = last_received_ - last_decoded_;
+  RTC_DCHECK_LE(last_received_delta, 0x7fff);
+  const uint16_t last_received_delta_and_decodability =
+      (last_received_delta << 1) | (decodability_flag_ ? 0x0001 : 0x0000);
+
+  ByteWriter<uint16_t>::WriteBigEndian(packet + *index,
+                                       last_received_delta_and_decodability);
+  *index += sizeof(uint16_t);
+
+  RTC_DCHECK_EQ(index_end, *index);
+  return true;
+}
+
+bool LossNotification::Parse(const CommonHeader& packet) {
+  RTC_DCHECK_EQ(packet.type(), kPacketType);
+  RTC_DCHECK_EQ(packet.fmt(), Psfb::kAfbMessageType);
+
+  if (packet.payload_size_bytes() <
+      kCommonFeedbackLength + kLossNotificationPayloadLength) {
+    return false;
+  }
+
+  const uint8_t* const payload = packet.payload();
+
+  if (ByteReader<uint32_t>::ReadBigEndian(&payload[8]) != kUniqueIdentifier) {
+    return false;
+  }
+
+  ParseCommonFeedback(payload);
+
+  last_decoded_ = ByteReader<uint16_t>::ReadBigEndian(&payload[12]);
+
+  const uint16_t last_received_delta_and_decodability =
+      ByteReader<uint16_t>::ReadBigEndian(&payload[14]);
+  last_received_ = last_decoded_ + (last_received_delta_and_decodability >> 1);
+  decodability_flag_ = (last_received_delta_and_decodability & 0x0001);
+
+  return true;
+}
+
+bool LossNotification::Set(uint16_t last_decoded,
+                           uint16_t last_received,
+                           bool decodability_flag) {
+  const uint16_t delta = last_received - last_decoded;
+  if (delta > 0x7fff) {
+    return false;
+  }
+  last_received_ = last_received;
+  last_decoded_ = last_decoded;
+  decodability_flag_ = decodability_flag;
+  return true;
+}
+
+}  // namespace rtcp
+}  // namespace webrtc