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/*
* Copyright (c) 2016 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 "webrtc/modules/rtp_rtcp/source/rtcp_packet/sli.h"
#include "webrtc/base/checks.h"
#include "webrtc/base/logging.h"
#include "webrtc/modules/rtp_rtcp/source/byte_io.h"
using webrtc::RTCPUtility::RtcpCommonHeader;
namespace webrtc {
namespace rtcp {
// RFC 4585: Feedback format.
//
// Common packet format:
//
// 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 | PT | length |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | SSRC of packet sender |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | SSRC of media source |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// : Feedback Control Information (FCI) :
// : :
//
// Slice loss indication (SLI) (RFC 4585).
// FCI:
// 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
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | First | Number | PictureID |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Sli::Macroblocks::Macroblocks(uint8_t picture_id,
uint16_t first,
uint16_t number) {
RTC_DCHECK_LE(first, 0x1fff);
RTC_DCHECK_LE(number, 0x1fff);
RTC_DCHECK_LE(picture_id, 0x3f);
item_ = (first << 19) | (number << 6) | picture_id;
}
void Sli::Macroblocks::Parse(const uint8_t* buffer) {
item_ = ByteReader<uint32_t>::ReadBigEndian(buffer);
}
void Sli::Macroblocks::Create(uint8_t* buffer) const {
ByteWriter<uint32_t>::WriteBigEndian(buffer, item_);
}
bool Sli::Parse(const RtcpCommonHeader& header, const uint8_t* payload) {
RTC_DCHECK(header.packet_type == kPacketType);
RTC_DCHECK(header.count_or_format == kFeedbackMessageType);
if (header.payload_size_bytes <
kCommonFeedbackLength + Macroblocks::kLength) {
LOG(LS_WARNING) << "Packet is too small to be a valid SLI packet";
return false;
}
size_t number_of_items =
(header.payload_size_bytes - kCommonFeedbackLength) /
Macroblocks::kLength;
ParseCommonFeedback(payload);
items_.resize(number_of_items);
const uint8_t* next_item = payload + kCommonFeedbackLength;
for (Macroblocks& item : items_) {
item.Parse(next_item);
next_item += Macroblocks::kLength;
}
return true;
}
bool Sli::Create(uint8_t* packet,
size_t* index,
size_t max_length,
RtcpPacket::PacketReadyCallback* callback) const {
RTC_DCHECK(!items_.empty());
while (*index + BlockLength() > max_length) {
if (!OnBufferFull(packet, index, callback))
return false;
}
CreateHeader(kFeedbackMessageType, kPacketType, HeaderLength(), packet,
index);
CreateCommonFeedback(packet + *index);
*index += kCommonFeedbackLength;
for (const Macroblocks& item : items_) {
item.Create(packet + *index);
*index += Macroblocks::kLength;
}
return true;
}
} // namespace rtcp
} // namespace webrtc
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