d8dccd57ea
got member read accessors, got Parse function. BUG=webrtc:5260 R=åsapersson Review URL: https://codereview.webrtc.org/1552773002 Cr-Commit-Position: refs/heads/master@{#11324}
134 lines
5.0 KiB
C++
134 lines
5.0 KiB
C++
/*
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* Copyright (c) 2016 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 "webrtc/modules/rtp_rtcp/source/rtcp_packet/remb.h"
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#include "webrtc/base/checks.h"
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#include "webrtc/base/logging.h"
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#include "webrtc/modules/rtp_rtcp/source/byte_io.h"
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using webrtc::RTCPUtility::RtcpCommonHeader;
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namespace webrtc {
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namespace rtcp {
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// Receiver Estimated Max Bitrate (REMB) (draft-alvestrand-rmcat-remb).
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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 | Unused = 0 |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// 8 | Unique identifier 'R' 'E' 'M' 'B' |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// 12 | Num SSRC | BR Exp | BR Mantissa |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// 16 | SSRC feedback |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// : ... :
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bool Remb::Parse(const RtcpCommonHeader& header, const uint8_t* payload) {
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RTC_DCHECK(header.packet_type == kPacketType);
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RTC_DCHECK(header.count_or_format == kFeedbackMessageType);
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if (header.payload_size_bytes < 16) {
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LOG(LS_WARNING) << "Payload length " << header.payload_size_bytes
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<< " is too small for Remb packet.";
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return false;
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}
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if (kUniqueIdentifier != ByteReader<uint32_t>::ReadBigEndian(&payload[8])) {
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LOG(LS_WARNING) << "REMB identifier not found, not a REMB packet.";
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return false;
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}
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uint8_t number_of_ssrcs = payload[12];
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if (header.payload_size_bytes !=
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kCommonFeedbackLength + (2 + number_of_ssrcs) * 4) {
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LOG(LS_WARNING) << "Payload size " << header.payload_size_bytes
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<< " does not match " << number_of_ssrcs << " ssrcs.";
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return false;
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}
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ParseCommonFeedback(payload);
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uint8_t exponenta = payload[13] >> 2;
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uint32_t mantissa = (static_cast<uint32_t>(payload[13] & 0x03) << 16) |
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ByteReader<uint16_t>::ReadBigEndian(&payload[14]);
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bitrate_bps_ = (mantissa << exponenta);
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const uint8_t* next_ssrc = payload + 16;
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ssrcs_.clear();
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ssrcs_.reserve(number_of_ssrcs);
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for (uint8_t i = 0; i < number_of_ssrcs; ++i) {
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ssrcs_.push_back(ByteReader<uint32_t>::ReadBigEndian(next_ssrc));
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next_ssrc += sizeof(uint32_t);
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}
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return true;
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}
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bool Remb::AppliesTo(uint32_t ssrc) {
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if (ssrcs_.size() >= kMaxNumberOfSsrcs) {
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LOG(LS_WARNING) << "Max number of REMB feedback SSRCs reached.";
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return false;
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}
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ssrcs_.push_back(ssrc);
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return true;
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}
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bool Remb::AppliesToMany(const std::vector<uint32_t>& ssrcs) {
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if (ssrcs_.size() + ssrcs.size() > kMaxNumberOfSsrcs) {
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LOG(LS_WARNING) << "Not enough space for all given SSRCs.";
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return false;
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}
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// Append.
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ssrcs_.insert(ssrcs_.end(), ssrcs.begin(), ssrcs.end());
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return true;
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}
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bool Remb::Create(uint8_t* packet,
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size_t* index,
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size_t max_length,
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RtcpPacket::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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size_t index_end = *index + BlockLength();
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CreateHeader(kFeedbackMessageType, kPacketType, HeaderLength(), packet,
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index);
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RTC_DCHECK_EQ(0u, Psfb::media_ssrc());
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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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const uint32_t kMaxMantissa = 0x3ffff; // 18 bits.
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uint32_t mantissa = bitrate_bps_;
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uint8_t exponenta = 0;
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while (mantissa > kMaxMantissa) {
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mantissa >>= 1;
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++exponenta;
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}
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packet[(*index)++] = ssrcs_.size();
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packet[(*index)++] = (exponenta << 2) | (mantissa >> 16);
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ByteWriter<uint16_t>::WriteBigEndian(packet + *index, mantissa & 0xffff);
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*index += sizeof(uint16_t);
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for (uint32_t ssrc : ssrcs_) {
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ByteWriter<uint32_t>::WriteBigEndian(packet + *index, ssrc);
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*index += sizeof(uint32_t);
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}
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RTC_DCHECK_EQ(index_end, *index);
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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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