/* * Copyright (c) 2016 The ZLMediaKit project authors. All Rights Reserved. * * This file is part of ZLMediaKit(https://github.com/xia-chu/ZLMediaKit). * * Use of this source code is governed by MIT license that can be found in the * LICENSE file in the root of the source tree. All contributing project authors * may be found in the AUTHORS file in the root of the source tree. */ #include "H264Rtp.h" namespace mediakit{ #if defined(_WIN32) #pragma pack(push, 1) #endif // defined(_WIN32) class FuFlags { public: #if __BYTE_ORDER == __BIG_ENDIAN unsigned start_bit: 1; unsigned end_bit: 1; unsigned reserved: 1; unsigned nal_type: 5; #else unsigned nal_type: 5; unsigned reserved: 1; unsigned end_bit: 1; unsigned start_bit: 1; #endif } PACKED; #if defined(_WIN32) #pragma pack(pop) #endif // defined(_WIN32) H264RtpDecoder::H264RtpDecoder() { _frame = obtainFrame(); } H264Frame::Ptr H264RtpDecoder::obtainFrame() { auto frame = FrameImp::create(); frame->_prefix_size = 4; return frame; } bool H264RtpDecoder::inputRtp(const RtpPacket::Ptr &rtp, bool key_pos) { return decodeRtp(rtp); } /* RTF3984 5.2节 Common Structure of the RTP Payload Format Table 1. Summary of NAL unit types and their payload structures Type Packet Type name Section --------------------------------------------------------- 0 undefined - 1-23 NAL unit Single NAL unit packet per H.264 5.6 24 STAP-A Single-time aggregation packet 5.7.1 25 STAP-B Single-time aggregation packet 5.7.1 26 MTAP16 Multi-time aggregation packet 5.7.2 27 MTAP24 Multi-time aggregation packet 5.7.2 28 FU-A Fragmentation unit 5.8 29 FU-B Fragmentation unit 5.8 30-31 undefined - */ bool H264RtpDecoder::decodeRtp(const RtpPacket::Ptr &rtp) { auto frame = rtp->getPayload(); auto length = rtp->getPayloadSize(); auto stamp = rtp->getStampMS(); auto seq = rtp->getSeq(); auto nal_type = *frame & 0x1F; auto nal_suffix = *frame & (~0x1F); if (nal_type >= 0 && nal_type < 24) { //a full frame _frame->_buffer.assign("\x00\x00\x00\x01", 4); _frame->_buffer.append((char *) frame, length); _frame->_pts = stamp; auto key = _frame->keyFrame(); onGetH264(_frame); return (key); //i frame } switch (nal_type) { case 24: { // 24 STAP-A 单一时间的组合包 bool haveIDR = false; auto ptr = frame + 1; while (true) { size_t off = ptr - frame; if (off >= length) { break; } //获取当前nalu的大小 uint16_t len = *ptr++; len <<= 8; len |= *ptr++; if (off + len > length) { break; } if (len > 0) { //有有效数据 _frame->_buffer.assign("\x00\x00\x00\x01", 4); _frame->_buffer.append((char *) ptr, len); _frame->_pts = stamp; if ((ptr[0] & 0x1F) == H264Frame::NAL_IDR) { haveIDR = true; } onGetH264(_frame); } ptr += len; } return haveIDR; } case 28: { //FU-A FuFlags *fu = (FuFlags *) (frame + 1); if (fu->start_bit) { //该帧的第一个rtp包 FU-A start //预留空间，防止频繁扩容拷贝 _frame->_buffer.reserve(_max_frame_size); _frame->_buffer.assign("\x00\x00\x00\x01", 4); _frame->_buffer.push_back(nal_suffix | fu->nal_type); _frame->_buffer.append((char *) frame + 2, length - 2); _frame->_pts = stamp; //该函数return时，保存下当前sequence,以便下次对比seq是否连续 _last_seq = seq; return _frame->keyFrame(); } if (seq != (uint16_t) (_last_seq + 1)) { //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 _frame->_buffer.clear(); WarnL << "rtp丢包: " << seq << " != " << _last_seq << " + 1,该帧被废弃"; return false; } if (!fu->end_bit) { //该帧的中间rtp包 FU-A mid _frame->_buffer.append((char *) frame + 2, length - 2); //该函数return时，保存下当前sequence,以便下次对比seq是否连续 _last_seq = seq; return false; } //该帧最后一个rtp包 FU-A end _frame->_buffer.append((char *) frame + 2, length - 2); _frame->_pts = stamp; //计算最大的帧 auto frame_size = _frame->size(); if (frame_size > _max_frame_size) { _max_frame_size = frame_size; } onGetH264(_frame); return false; } default: { // 29 FU-B 单NAL单元B模式 // 25 STAP-B 单一时间的组合包 // 26 MTAP16 多个时间的组合包 // 27 MTAP24 多个时间的组合包 WarnL << "不支持的rtp类型:" << (int) nal_type << " " << seq; return false; } } } void H264RtpDecoder::onGetH264(const H264Frame::Ptr &frame) { //rtsp没有dts，那么根据pts排序算法生成dts _dts_generator.getDts(frame->_pts,frame->_dts); RtpCodec::inputFrame(frame); _frame = obtainFrame(); } //////////////////////////////////////////////////////////////////////// H264RtpEncoder::H264RtpEncoder(uint32_t ssrc, uint32_t mtu, uint32_t sample_rate, uint8_t pt, uint8_t interleaved) : RtpInfo(ssrc, mtu, sample_rate, pt, interleaved) { } void H264RtpEncoder::inputFrame(const Frame::Ptr &frame) { auto ptr = frame->data() + frame->prefixSize(); auto len = frame->size() - frame->prefixSize(); auto pts = frame->pts(); auto nal_type = H264_TYPE(ptr[0]); if(nal_type == H264Frame::NAL_SEI || nal_type == H264Frame::NAL_AUD){ return; } if(nal_type == H264Frame::NAL_SPS){ _sps = std::string(ptr,len); return; } if(nal_type == H264Frame::NAL_PPS){ _pps = std::string(ptr,len); return; } if(nal_type == H264Frame::NAL_IDR) {// 保证每一个I帧前都有SPS与PPS ,为了兼容webrtc 需要在一个rtp包中，并且只能是 STAP-A // https://blog.csdn.net/momo0853/article/details/88872873 auto rtp = makeRtp(getTrackType(), nullptr,_sps.size()+_pps.size()+2*2+1,true,pts); uint8_t *payload = rtp->getPayload(); payload[0] = 24; payload[1] = _sps.size() >> 8; payload[2] = _sps.size() & 0xff; memcpy(payload+3,(uint8_t *) _sps.data(),_sps.size()); payload[_sps.size()+3] = _pps.size() >> 8; payload[_sps.size()+4] = _pps.size() & 0xff; memcpy(payload+3+_sps.size()+2,(uint8_t *) _pps.data(),_pps.size()); RtpCodec::inputRtp(rtp,true); } auto packet_size = getMaxSize() - 2; //InfoL<<"nal type = "<