ef3d805f6e
explicetly unchanged. BUG=webrtc:5260 R=åsapersson Review URL: https://codereview.webrtc.org/1578713002 Cr-Commit-Position: refs/heads/master@{#11201}
120 lines
4.1 KiB
C++
120 lines
4.1 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/tmmbn.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::PT_RTPFB;
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using webrtc::RTCPUtility::RTCPPacketRTPFBTMMBN;
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using webrtc::RTCPUtility::RTCPPacketRTPFBTMMBRItem;
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namespace webrtc {
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namespace rtcp {
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namespace {
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const uint32_t kUnusedMediaSourceSsrc0 = 0;
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void AssignUWord8(uint8_t* buffer, size_t* offset, uint8_t value) {
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buffer[(*offset)++] = value;
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}
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void AssignUWord32(uint8_t* buffer, size_t* offset, uint32_t value) {
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ByteWriter<uint32_t>::WriteBigEndian(buffer + *offset, value);
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*offset += 4;
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}
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void ComputeMantissaAnd6bitBase2Exponent(uint32_t input_base10,
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uint8_t bits_mantissa,
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uint32_t* mantissa,
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uint8_t* exp) {
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// input_base10 = mantissa * 2^exp
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assert(bits_mantissa <= 32);
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uint32_t mantissa_max = (1 << bits_mantissa) - 1;
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uint8_t exponent = 0;
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for (uint32_t i = 0; i < 64; ++i) {
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if (input_base10 <= (mantissa_max << i)) {
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exponent = i;
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break;
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}
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}
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*exp = exponent;
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*mantissa = (input_base10 >> exponent);
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}
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void CreateTmmbrItem(const RTCPPacketRTPFBTMMBRItem& tmmbr_item,
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uint8_t* buffer,
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size_t* pos) {
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uint32_t bitrate_bps = tmmbr_item.MaxTotalMediaBitRate * 1000;
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uint32_t mantissa = 0;
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uint8_t exp = 0;
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ComputeMantissaAnd6bitBase2Exponent(bitrate_bps, 17, &mantissa, &exp);
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AssignUWord32(buffer, pos, tmmbr_item.SSRC);
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AssignUWord8(buffer, pos, (exp << 2) + ((mantissa >> 15) & 0x03));
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AssignUWord8(buffer, pos, mantissa >> 7);
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AssignUWord8(buffer, pos, (mantissa << 1) +
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((tmmbr_item.MeasuredOverhead >> 8) & 0x01));
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AssignUWord8(buffer, pos, tmmbr_item.MeasuredOverhead);
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}
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// Temporary Maximum Media Stream Bit Rate Notification (TMMBN) (RFC 5104).
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//
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// FCI:
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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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// | SSRC |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | MxTBR Exp | MxTBR Mantissa |Measured Overhead|
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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void CreateTmmbn(const RTCPPacketRTPFBTMMBN& tmmbn,
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const std::vector<RTCPPacketRTPFBTMMBRItem>& tmmbn_items,
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uint8_t* buffer,
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size_t* pos) {
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AssignUWord32(buffer, pos, tmmbn.SenderSSRC);
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AssignUWord32(buffer, pos, kUnusedMediaSourceSsrc0);
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for (uint8_t i = 0; i < tmmbn_items.size(); ++i) {
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CreateTmmbrItem(tmmbn_items[i], buffer, pos);
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}
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}
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} // namespace
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bool Tmmbn::WithTmmbr(uint32_t ssrc, uint32_t bitrate_kbps, uint16_t overhead) {
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assert(overhead <= 0x1ff);
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if (tmmbn_items_.size() >= kMaxNumberOfTmmbrs) {
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LOG(LS_WARNING) << "Max TMMBN size reached.";
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return false;
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}
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RTCPPacketRTPFBTMMBRItem tmmbn_item;
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tmmbn_item.SSRC = ssrc;
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tmmbn_item.MaxTotalMediaBitRate = bitrate_kbps;
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tmmbn_item.MeasuredOverhead = overhead;
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tmmbn_items_.push_back(tmmbn_item);
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return true;
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}
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bool Tmmbn::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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const uint8_t kFmt = 4;
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CreateHeader(kFmt, PT_RTPFB, HeaderLength(), packet, index);
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CreateTmmbn(tmmbn_, tmmbn_items_, packet, 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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