Github:

https://github.com/gongluck/FFmpeg4.0-study.git

#include <iostream>
using namespace std;

extern "C"
{
#include "libavformat/avformat.h"
#include "libavutil/time.h"
}
#pragma comment(lib, "avformat.lib")
#pragma comment(lib, "avutil.lib")
#pragma comment(lib, "avcodec.lib")

char av_error[AV_ERROR_MAX_STRING_SIZE] = { 0 };
#define av_err2str(errnum) \
    av_make_error_string(av_error, AV_ERROR_MAX_STRING_SIZE, errnum)

#define INFILE  "in.flv"
#define RTMP    "rtmp://192.168.140.128/live/test"
#define RTSP    "rtsp://184.72.239.149/vod/mp4://BigBuckBunny_175k.mov"

int file2rtmp()
{
    int ret = 0;
    //封装上下文
    AVFormatContext* ictx = nullptr;
    AVFormatContext* octx = nullptr;
    const char* iurl = INFILE;
    const char* ourl = RTMP;
    int64_t starttime;

    ret = avformat_network_init();
    if (ret != 0)
    {
        cout << av_err2str(ret) << endl;
        goto END;
    }

    //打开文件，解封文件头
    ret = avformat_open_input(&ictx, iurl, nullptr, nullptr);
    if (ret != 0)
    {
        cout << av_err2str(ret) << endl;
        goto END;
    }
    cerr << "open file " << iurl << " success." << endl;

    //获取音视频流信息,h264 flv
    ret = avformat_find_stream_info(ictx, nullptr);
    if (ret != 0)
    {
        cout << av_err2str(ret) << endl;
        goto END;
    }

    //打印媒体信息
    av_dump_format(ictx, 0, iurl, 0);

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

    //输出流
    ret = avformat_alloc_output_context2(&octx, av_guess_format(nullptr, INFILE, nullptr), nullptr, ourl);
    if (ret != 0)
    {
        cout << av_err2str(ret) << endl;
        goto END;
    }
    cout << "octx create success." << endl;

    //配置输出流
    for (int i = 0; i < ictx->nb_streams; ++i)
    {
        //创建流
        AVStream* ostream = avformat_new_stream(octx, avcodec_find_encoder(ictx->streams[i]->codecpar->codec_id));
        if (ostream == nullptr)
            goto END;
        //复制配置信息
        ret = avcodec_parameters_copy(ostream->codecpar, ictx->streams[i]->codecpar);
        if (ret != 0)
        {
            cout << av_err2str(ret) << endl;
            goto END;
        }
        ostream->codecpar->codec_tag = 0;//标记不需要重新编解码
    }
    av_dump_format(octx, 0, ourl, 1);

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

    //推流
    ret = avio_open2(&octx->pb, ourl, AVIO_FLAG_WRITE, nullptr, nullptr);
    if (ret < 0)
    {
        cout << av_err2str(ret) << endl;
        goto END;
    }

    //写入头信息
    ret = avformat_write_header(octx, nullptr);
    if (ret < 0)
    {
        cout << av_err2str(ret) << endl;
        goto END;
    }

    //推流每一帧数据
    AVPacket pkt;
    starttime = av_gettime();
    while (av_read_frame(ictx, &pkt) == 0)
    {
        //计算转换pts dts
        AVRational itime = ictx->streams[pkt.stream_index]->time_base;
        AVRational otime = octx->streams[pkt.stream_index]->time_base;
        pkt.pts = av_rescale_q_rnd(pkt.pts, itime, otime, (AVRounding)(AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX));
        pkt.dts = av_rescale_q_rnd(pkt.dts, itime, otime, (AVRounding)(AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX));
        pkt.duration = av_rescale_q_rnd(pkt.duration, itime, otime, (AVRounding)(AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX));
        pkt.pos = -1;

        if (ictx->streams[pkt.stream_index]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO)
        {
            int64_t nowtime = av_gettime() - starttime;
            int64_t dts = pkt.dts * av_q2d(octx->s