mirror of
https://github.com/ZLMediaKit/ZLMediaKit.git
synced 2024-10-31 16:47:28 +08:00
256 lines
9.0 KiB
C++
256 lines
9.0 KiB
C++
/*
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* Copyright (c) 2016 The ZLMediaKit project authors. All Rights Reserved.
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*
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* This file is part of ZLMediaKit(https://github.com/xiongziliang/ZLMediaKit).
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*
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* Use of this source code is governed by MIT license that can be found in the
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* LICENSE file in the root of the source tree. All contributing project authors
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* may be found in the AUTHORS file in the root of the source tree.
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*/
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#include "H264Rtp.h"
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namespace mediakit{
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typedef struct {
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unsigned S :1;
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unsigned E :1;
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unsigned R :1;
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unsigned type :5;
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} FU;
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static bool MakeFU(uint8_t in, FU &fu) {
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fu.S = in >> 7;
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fu.E = (in >> 6) & 0x01;
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fu.R = (in >> 5) & 0x01;
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fu.type = in & 0x1f;
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if (fu.R != 0) {
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return false;
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}
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return true;
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}
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H264RtpDecoder::H264RtpDecoder() {
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_h264frame = obtainFrame();
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}
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H264Frame::Ptr H264RtpDecoder::obtainFrame() {
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//从缓存池重新申请对象，防止覆盖已经写入环形缓存的对象
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auto frame = ResourcePoolHelper<H264Frame>::obtainObj();
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frame->_buffer.clear();
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frame->_prefix_size = 4;
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return frame;
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}
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bool H264RtpDecoder::inputRtp(const RtpPacket::Ptr &rtp, bool key_pos) {
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return decodeRtp(rtp);
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}
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bool H264RtpDecoder::decodeRtp(const RtpPacket::Ptr &rtppack) {
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/**
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* h264帧类型
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* Type==1:P/B frame
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* Type==5:IDR frame
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* Type==6:SEI frame
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* Type==7:SPS frame
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* Type==8:PPS frame
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*/
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/*
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RTF3984 5.2节 Common Structure of the RTP Payload Format
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Table 1. Summary of NAL unit types and their payload structures
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Type Packet Type name Section
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---------------------------------------------------------
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0 undefined -
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1-23 NAL unit Single NAL unit packet per H.264 5.6
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24 STAP-A Single-time aggregation packet 5.7.1
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25 STAP-B Single-time aggregation packet 5.7.1
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26 MTAP16 Multi-time aggregation packet 5.7.2
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27 MTAP24 Multi-time aggregation packet 5.7.2
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28 FU-A Fragmentation unit 5.8
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29 FU-B Fragmentation unit 5.8
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30-31 undefined -
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*/
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const uint8_t *frame = (uint8_t *) rtppack->data() + rtppack->offset;
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int length = rtppack->size() - rtppack->offset;
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int nal_type = *frame & 0x1F;
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int nal_suffix = *frame & (~0x1F);
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if (nal_type >= 0 && nal_type < 24) {
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//a full frame
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_h264frame->_buffer.assign("\x0\x0\x0\x1", 4);
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_h264frame->_buffer.append((char *) frame, length);
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_h264frame->_pts = rtppack->timeStamp;
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auto key = _h264frame->keyFrame();
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onGetH264(_h264frame);
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return (key); //i frame
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}
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switch (nal_type){
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case 24:{
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// 24 STAP-A 单一时间的组合包
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bool haveIDR = false;
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auto ptr = frame + 1;
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while (true) {
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int off = ptr - frame;
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if (off >= length) {
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break;
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}
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//获取当前nalu的大小
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uint16_t len = *ptr++;
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len <<= 8;
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len |= *ptr++;
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if (off + len > length) {
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break;
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}
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if (len > 0) {
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//有有效数据
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_h264frame->_buffer.assign("\x0\x0\x0\x1", 4);
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_h264frame->_buffer.append((char *) ptr, len);
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_h264frame->_pts = rtppack->timeStamp;
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if ((ptr[0] & 0x1F) == H264Frame::NAL_IDR) {
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haveIDR = true;
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}
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onGetH264(_h264frame);
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}
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ptr += len;
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}
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return haveIDR;
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}
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case 28:{
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//FU-A
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FU fu;
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MakeFU(frame[1], fu);
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if (fu.S) {
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//该帧的第一个rtp包 FU-A start
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_h264frame->_buffer.assign("\x0\x0\x0\x1", 4);
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_h264frame->_buffer.push_back(nal_suffix | fu.type);
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_h264frame->_buffer.append((char *) frame + 2, length - 2);
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_h264frame->_pts = rtppack->timeStamp;
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//该函数return时，保存下当前sequence,以便下次对比seq是否连续
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_lastSeq = rtppack->sequence;
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return _h264frame->keyFrame();
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}
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if (rtppack->sequence != _lastSeq + 1 && rtppack->sequence != 0) {
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//中间的或末尾的rtp包，其seq必须连续(如果回环了则判定为连续)，否则说明rtp丢包，那么该帧不完整，必须得丢弃
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_h264frame->_buffer.clear();
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WarnL << "rtp丢包: " << rtppack->sequence << " != " << _lastSeq << " + 1,该帧被废弃";
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return false;
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}
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if (!fu.E) {
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//该帧的中间rtp包 FU-A mid
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_h264frame->_buffer.append((char *) frame + 2, length - 2);
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//该函数return时，保存下当前sequence,以便下次对比seq是否连续
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_lastSeq = rtppack->sequence;
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return false;
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}
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//该帧最后一个rtp包 FU-A end
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_h264frame->_buffer.append((char *) frame + 2, length - 2);
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_h264frame->_pts = rtppack->timeStamp;
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onGetH264(_h264frame);
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return false;
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}
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default: {
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// 29 FU-B 单NAL单元B模式
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// 25 STAP-B 单一时间的组合包
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// 26 MTAP16 多个时间的组合包
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// 27 MTAP24 多个时间的组合包
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// 0 udef
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// 30 udef
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// 31 udef
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WarnL << "不支持的rtp类型:" << (int) nal_type << " " << rtppack->sequence;
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return false;
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}
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}
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}
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void H264RtpDecoder::onGetH264(const H264Frame::Ptr &frame) {
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//rtsp没有dts，那么根据pts排序算法生成dts
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_dts_generator.getDts(frame->_pts,frame->_dts);
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//写入环形缓存
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RtpCodec::inputFrame(frame);
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_h264frame = obtainFrame();
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}
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////////////////////////////////////////////////////////////////////////
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H264RtpEncoder::H264RtpEncoder(uint32_t ui32Ssrc,
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uint32_t ui32MtuSize,
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uint32_t ui32SampleRate,
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uint8_t ui8PayloadType,
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uint8_t ui8Interleaved) :
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RtpInfo(ui32Ssrc,
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ui32MtuSize,
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ui32SampleRate,
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ui8PayloadType,
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ui8Interleaved) {
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}
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void H264RtpEncoder::inputFrame(const Frame::Ptr &frame) {
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GET_CONFIG(uint32_t,cycleMS,Rtp::kCycleMS);
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auto ptr = frame->data() + frame->prefixSize();
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auto pts = frame->pts() % cycleMS;
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auto len = frame->size() - frame->prefixSize();
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auto nal_type = H264_TYPE(ptr[0]);
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auto max_rtp_size = _ui32MtuSize - 2;
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//超过MTU则按照FU-A模式打包
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if (len > max_rtp_size) {
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//最高位bit为forbidden_zero_bit,
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//后面2bit为nal_ref_idc(帧重要程度),00:可以丢,11:不能丢
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//末尾5bit为nalu type，固定为28(FU-A)
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unsigned char nal_fu_a = (*((unsigned char *) ptr) & (~0x1F)) | 28;
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unsigned char s_e_r_flags;
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bool fu_a_start = true;
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bool mark_bit = false;
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int offset = 1;
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while (!mark_bit) {
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if (len <= offset + max_rtp_size) {
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//已经拆分结束
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max_rtp_size = len - offset;
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mark_bit = true;
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//FU-A end
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s_e_r_flags = (1 << 6) | nal_type;
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} else if (fu_a_start) {
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//FU-A start
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s_e_r_flags = (1 << 7) | nal_type;
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} else {
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//FU-A mid
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s_e_r_flags = nal_type;
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}
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{
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//传入nullptr先不做payload的内存拷贝
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auto rtp = makeRtp(getTrackType(), nullptr, max_rtp_size + 2, mark_bit, pts);
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//rtp payload 负载部分
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uint8_t *payload = (uint8_t*)rtp->data() + rtp->offset;
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//FU-A 第1个字节
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payload[0] = nal_fu_a;
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//FU-A 第2个字节
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payload[1] = s_e_r_flags;
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//H264 数据
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memcpy(payload + 2, (unsigned char *) ptr + offset, max_rtp_size);
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//输入到rtp环形缓存
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RtpCodec::inputRtp(rtp, fu_a_start && nal_type == H264Frame::NAL_IDR);
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}
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offset += max_rtp_size;
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fu_a_start = false;
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}
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} else {
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//如果帧长度不超过mtu, 则按照Single NAL unit packet per H.264 方式打包
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makeH264Rtp(ptr, len, false, false, pts);
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}
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}
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void H264RtpEncoder::makeH264Rtp(const void* data, unsigned int len, bool mark, bool gop_pos, uint32_t uiStamp) {
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RtpCodec::inputRtp(makeRtp(getTrackType(), data, len, mark, uiStamp), gop_pos);
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}
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}//namespace mediakit
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