#include <stdio.h>
#include "ffmpeg/include/libavformat/avformat.h"
#include "ffmpeg/include/libavcodec/avcodec.h"

void publishstream() {
    const char* srcfile = "t.mp4";
    const char* streamseverurl = "rtmp://localhost/rtmpdemo/test1";
    av_register_all();
    avformat_network_init();
    av_log_set_level(AV_LOG_DEBUG);
    int status = 0;
    AVFormatContext* formatcontext = avformat_alloc_context();
    status = avformat_open_input(&formatcontext, srcfile, NULL, NULL);
    if (status >= 0) {
        status = avformat_find_stream_info(formatcontext, NULL);
        if (status >= 0) {
            int videoindex = -1;
            for (int i = 0; i < formatcontext->nb_streams; i ++) {
                if (formatcontext->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
                    videoindex = i;
                    break;
                }
            }
            if (videoindex >= 0) {
                AVFormatContext* outformatcontext;
                avformat_alloc_output_context2(&outformatcontext, NULL, "flv", streamseverurl);
                if (outformatcontext) {
                    status = -1;
                    for (int i = 0; i < formatcontext->nb_streams; i ++) {
                        AVStream* onestream = formatcontext->streams[i];
                        AVStream* newstream = avformat_new_stream(outformatcontext, onestream->codec->codec);
                        status = newstream ? 0 : -1;
                        if (status == 0) {
                            status = avcodec_copy_context(newstream->codec, onestream->codec);
                            if (status >= 0) {
                                newstream->codec->codec_tag = 0;
                                if (outformatcontext->oformat->flags & AVFMT_GLOBALHEADER) {
                                    newstream->codec->flags |= CODEC_FLAG_GLOBAL_HEADER;
                                }
                            }
                        }
                    }

if (status >= 0) {
    AVOutputFormat* outformat = outformatcontext->oformat;
    av_usleep(5*1000*1000); // 故意等一下再开始推流，让拉流的客户端有时间启动，以拿到视频的pps/sps
    if (!(outformat->flags & AVFMT_NOFILE)) {
        av_dump_format(outformatcontext, 0, streamseverurl, 1);
        status = avio_open(&outformatcontext->pb, streamseverurl, AVIO_FLAG_WRITE);
        if (status >= 0) {
            status = avformat_write_header(outformatcontext, NULL);
            if (status >= 0) {
                AVPacket packet;
                int videoframeidx = 0;
                int64_t starttime = av_gettime();
                while (1) {
                    status = av_read_frame(formatcontext, &packet);
                    if (status < 0) {
                        break;
                    }

                                        if (packet.pts == AV_NOPTS_VALUE) {
                                            av_log(NULL, AV_LOG_DEBUG, "set pakcet.pts\n");
                                            AVRational video_time_base = formatcontext->streams[videoindex]->time_base;
                                            int64_t frameduration = (double)AV_TIME_BASE / av_q2d(formatcontext->streams[videoindex]->r_frame_rate);
                                            packet.pts = (double)(videoframeidx * frameduration) / (double)(av_q2d(video_time_base) * AV_TIME_BASE);
                                            packet.dts = packet.pts;
                                            packet.duration = (double)frameduration / (double)(av_q2d(video_time_base) * AV_TIME_BASE);
                                        }
                                        if (packet.stream_index == videoindex) {
                                            AVRational video_time_base = formatcontext->streams[videoindex]->time_base;
                                            AVRational time_base_q = {1, AV_TIME_BASE};
                                            int64_t cur_pts = av_rescale_q(packet.dts, video_time_base, time_base_q);
                                            int64_t curtime = av_gettime() - starttime;
                                            av_log(NULL, AV_LOG_DEBUG, "on video frame curpts=%lld curtime=%lld\n", cur_pts, curtime);
                                            if (cur_pts > curtime) {
                                                av_usleep(cur_pts - curtime);
                                            }
                                        }
                                        AVStream* instream = formatcontext->streams[packet.stream_index];
                                        AVStream* outstream = outformatcontext->streams[packet.stream_index];
                                        packet.pts = av_rescale_q_rnd(packet.pts, instream->time_base, outstream->time_base, AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX);
                                        packet.dts = av_rescale_q_rnd(packet.dts, instream->time_base, outstream->time_base, AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX);
                                        packet.duration = av_rescale_q(packet.duration, instream->time_base, outstream->time_base);
                                        packet.pos = -1;
                                        if (packet.stream_index == videoindex) {
                                            videoframeidx ++;
                                        }
                                        status = av_interleaved_write_frame(outformatcontext, &packet);
                                        if (status < 0) {
                                            break;
                                        }
                                    }
                                    av_write_trailer(outformatcontext);
                                }
                                avio_close(outformatcontext->pb);
                            }
                        }
                    }
                    avformat_free_context(outformatcontext);
                }
            }
        }
        avformat_close_input(&formatcontext);
    }
    avformat_free_context(formatcontext);
}

int main(int argc, char *argv[])
{
    publishstream();
    return 0;
}

这里以本地的视频文件作为内容，模拟了直播推流，功能上相当于直接调用ffmpeg命令：

sudo ffmpeg -re -i Movie-1.mp4 -vcodec copy -f flv rtmp://localhost/rtmpdemo/test1
当然也可以边录制，边推送。

当然也可以在不同的电脑或手机上，拉流播放，这里有一个前提，就是把nginx架设好并启动

直播开始后，这里的流服务器并没有给中途拉流的客户端发送视频解码所必须的参数（pps/sps），所以在测试的时候，要保证拉流端能拿到第一帧数据，比如演示代码中故意sleep几秒后才开始推流，让拉流端有时间开启并拿到推上去的所有数据（包括关键参数）。