ZLMediaKit/src/RTP/H264RtpCodec.cpp

//
// Created by xzl on 2018/10/18.
//

#include "H264RtpCodec.h"

void H264RtpDecoder::inputRtp(const RtpPacket::Ptr &rtp, bool key_pos) {
    RtpCodec::inputRtp(rtp, decodeRtp(rtp,key_pos));
}

bool H264RtpDecoder::decodeRtp(const RtpPacket::Ptr &rtppack, bool key_pos) {
    /**
     * h264帧类型
     * Type==1:P/B frame
     * Type==5:IDR frame
     * Type==6:SEI frame
     * Type==7:SPS frame
     * Type==8:PPS frame
     */

    const uint8_t *frame = (uint8_t *) rtppack->payload + rtppack->offset;
    int length = rtppack->length - rtppack->offset;
    NALU nal;
    MakeNalu(*frame, nal);

    if (nal.type >= 0 && nal.type < 24) {
        //a full frame
        m_h264frame->buffer.assign("\x0\x0\x0\x1", 4);
        m_h264frame->buffer.append((char *)frame, length);
        m_h264frame->type = nal.type;
        m_h264frame->timeStamp = rtppack->timeStamp / 90;
        m_h264frame->sequence = rtppack->sequence;
        auto isIDR = m_h264frame->type == 5;
        onGetH264(m_h264frame);
        return (isIDR); //i frame
    }

    if (nal.type == 28) {
        //FU-A
        FU fu;
        MakeFU(frame[1], fu);
        if (fu.S == 1) {
            //FU-A start
            char tmp = (nal.forbidden_zero_bit << 7 | nal.nal_ref_idc << 5 | fu.type);
            m_h264frame->buffer.assign("\x0\x0\x0\x1", 4);
            m_h264frame->buffer.push_back(tmp);
            m_h264frame->buffer.append((char *)frame + 2, length - 2);
            m_h264frame->type = fu.type;
            m_h264frame->timeStamp = rtppack->timeStamp / 90;
            m_h264frame->sequence = rtppack->sequence;
            return (m_h264frame->type == 5); //i frame
        }

        if (rtppack->sequence != (uint16_t)(m_h264frame->sequence + 1)) {
            m_h264frame->buffer.clear();
            WarnL << "丢包,帧废弃:" << rtppack->sequence << "," << m_h264frame->sequence;
            return false;
        }
        m_h264frame->sequence = rtppack->sequence;
        if (fu.E == 1) {
            //FU-A end
            m_h264frame->buffer.append((char *)frame + 2, length - 2);
            m_h264frame->timeStamp = rtppack->timeStamp / 90;
            auto isIDR = m_h264frame->type == 5;
            onGetH264(m_h264frame);
            return isIDR;
        }
        //FU-A mid
        m_h264frame->buffer.append((char *)frame + 2, length - 2);
        return false;
    }

    WarnL << "不支持的rtp类型:" << nal.type << " " << rtppack->sequence;
    return false;
    // 29 FU-B     单NAL单元B模式
    // 24 STAP-A   单一时间的组合包
    // 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
    // 0 udef
    // 30 udef
    // 31 udef
}

void H264RtpDecoder::onGetH264(const H264Frame::Ptr &frame) {
    //写入环形缓存
    RtpCodec::inputFame(frame,frame->type == 5);
    //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
    m_h264frame = m_framePool.obtain();
    m_h264frame->buffer.clear();
}

////////////////////////////////////////////////////////////////////////

H264RtpEncoder::H264RtpEncoder(uint32_t ui32Ssrc,
                               uint32_t ui32MtuSize,
                               uint32_t ui32SampleRate,
                               uint8_t ui8PlayloadType,
                               uint8_t ui8Interleaved) :
        RtpInfo(ui32Ssrc,
                ui32MtuSize,
                ui32SampleRate,
                ui8PlayloadType,
                ui8Interleaved) {
}

void H264RtpEncoder::inputFame(const Frame::Ptr &frame, bool key_pos) {
    RtpCodec::inputFame(frame, key_pos);

    GET_CONFIG_AND_REGISTER(uint32_t,cycleMS,Config::Rtp::kCycleMS);
    auto uiStamp = frame->stamp();
    auto pcData = frame->data();
    auto iLen = frame->size();

    uiStamp %= cycleMS;
    int iSize = m_ui32MtuSize - 2;
    if (iLen > iSize) { //超过MTU
        const unsigned char s_e_r_Start = 0x80;
        const unsigned char s_e_r_Mid = 0x00;
        const unsigned char s_e_r_End = 0x40;
        //获取帧头数据，1byte
        unsigned char naluType = *((unsigned char *) pcData) & 0x1f; //获取NALU的5bit 帧类型

        unsigned char nal_ref_idc = *((unsigned char *) pcData) & 0x60; //获取NALU的2bit 帧重要程度 00 可以丢 11不能丢
        //nal_ref_idc = 0x60;
        //组装FU-A帧头数据 2byte
        unsigned char f_nri_type = nal_ref_idc + 28;//F为0 1bit,nri上面获取到2bit,28为FU-A分片类型5bit
        unsigned char s_e_r_type = naluType;
        bool bFirst = true;
        bool mark = false;
        int nOffset = 1;
        while (!mark) {
            if (iLen < nOffset + iSize) {			//是否拆分结束
                iSize = iLen - nOffset;
                mark = true;
                s_e_r_type = s_e_r_End + naluType;
            } else {
                if (bFirst == true) {
                    s_e_r_type = s_e_r_Start + naluType;
                    bFirst = false;
                } else {
                    s_e_r_type = s_e_r_Mid + naluType;
                }
            }
            memcpy(m_aucSectionBuf, &f_nri_type, 1);
            memcpy(m_aucSectionBuf + 1, &s_e_r_type, 1);
            memcpy(m_aucSectionBuf + 2, (unsigned char *) pcData + nOffset, iSize);
            nOffset += iSize;
            makeH264Rtp(m_aucSectionBuf, iSize + 2, mark, uiStamp);
        }
    } else {
        makeH264Rtp(pcData, iLen, true, uiStamp);
    }
}

void H264RtpEncoder::makeH264Rtp(const void* data, unsigned int len, bool mark, uint32_t uiStamp) {
    uint16_t ui16RtpLen = len + 12;
    m_ui32TimeStamp = (m_ui32SampleRate / 1000) * uiStamp;
    uint32_t ts = htonl(m_ui32TimeStamp);
    uint16_t sq = htons(m_ui16Sequence);
    uint32_t sc = htonl(m_ui32Ssrc);

    auto rtppkt = obtainRtp();
    unsigned char *pucRtp = rtppkt->payload;
    pucRtp[0] = '$';
    pucRtp[1] = m_ui8Interleaved;
    pucRtp[2] = ui16RtpLen >> 8;
    pucRtp[3] = ui16RtpLen & 0x00FF;
    pucRtp[4] = 0x80;
    pucRtp[5] = (mark << 7) | m_ui8PlayloadType;
    memcpy(&pucRtp[6], &sq, 2);
    memcpy(&pucRtp[8], &ts, 4);
    //ssrc
    memcpy(&pucRtp[12], &sc, 4);
    //playload
    memcpy(&pucRtp[16], data, len);

    rtppkt->PT = m_ui8PlayloadType;
    rtppkt->interleaved = m_ui8Interleaved;
    rtppkt->mark = mark;
    rtppkt->length = len + 16;
    rtppkt->sequence = m_ui16Sequence;
    rtppkt->timeStamp = m_ui32TimeStamp;
    rtppkt->ssrc = m_ui32Ssrc;
    rtppkt->type = TrackVideo;
    rtppkt->offset = 16;

    uint8_t type = ((uint8_t *) (data))[0] & 0x1F;
    RtpCodec::inputRtp(rtppkt,type == 5);
    m_ui16Sequence++;
}