2c13297bf5
Cleaning/Parsing will be done in the https://codereview.webrtc.org/1550293003/ BUG=webrtc:5260 R=asapersson@webrtc.org, åsapersson Review URL: https://codereview.webrtc.org/1583233007 . Cr-Commit-Position: refs/heads/master@{#11272}
103 lines
3.5 KiB
C++
103 lines
3.5 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/rpsi.h"
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#include "webrtc/modules/rtp_rtcp/source/byte_io.h"
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using webrtc::RTCPUtility::PT_PSFB;
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using webrtc::RTCPUtility::RTCPPacketPSFBRPSI;
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namespace webrtc {
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namespace rtcp {
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namespace {
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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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// Reference picture selection indication (RPSI) (RFC 4585).
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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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// | PB |0| Payload Type| Native RPSI bit string |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | defined per codec ... | Padding (0) |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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void CreateRpsi(const RTCPPacketPSFBRPSI& rpsi,
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uint8_t padding_bytes,
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uint8_t* buffer,
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size_t* pos) {
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// Native bit string should be a multiple of 8 bits.
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assert(rpsi.NumberOfValidBits % 8 == 0);
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AssignUWord32(buffer, pos, rpsi.SenderSSRC);
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AssignUWord32(buffer, pos, rpsi.MediaSSRC);
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AssignUWord8(buffer, pos, padding_bytes * 8);
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AssignUWord8(buffer, pos, rpsi.PayloadType);
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memcpy(buffer + *pos, rpsi.NativeBitString, rpsi.NumberOfValidBits / 8);
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*pos += rpsi.NumberOfValidBits / 8;
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memset(buffer + *pos, 0, padding_bytes);
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*pos += padding_bytes;
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}
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} // namespace
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bool Rpsi::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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assert(rpsi_.NumberOfValidBits > 0);
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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 = 3;
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CreateHeader(kFmt, PT_PSFB, HeaderLength(), packet, index);
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CreateRpsi(rpsi_, padding_bytes_, packet, index);
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return true;
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}
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void Rpsi::WithPictureId(uint64_t picture_id) {
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const uint32_t kPidBits = 7;
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const uint64_t k7MsbZeroMask = 0x1ffffffffffffffULL;
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uint8_t required_bytes = 0;
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uint64_t shifted_pid = picture_id;
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do {
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++required_bytes;
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shifted_pid = (shifted_pid >> kPidBits) & k7MsbZeroMask;
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} while (shifted_pid > 0);
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// Convert picture id to native bit string (natively defined by the video
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// codec).
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int pos = 0;
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for (int i = required_bytes - 1; i > 0; i--) {
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rpsi_.NativeBitString[pos++] =
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0x80 | static_cast<uint8_t>(picture_id >> (i * kPidBits));
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}
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rpsi_.NativeBitString[pos++] = static_cast<uint8_t>(picture_id & 0x7f);
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rpsi_.NumberOfValidBits = pos * 8;
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// Calculate padding bytes (to reach next 32-bit boundary, 1, 2 or 3 bytes).
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padding_bytes_ = 4 - ((2 + required_bytes) % 4);
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if (padding_bytes_ == 4) {
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padding_bytes_ = 0;
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}
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}
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} // namespace rtcp
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} // namespace webrtc
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