ffmpeg推流 —— RTMP推流例程

参考：

雷霄骅 - 最简单的基于FFmpeg的推流器（以推送RTMP为例）

nginx+rtmp配置，网页播放rtmp流（实测可用）

RTMP推流例程：

#include <stdio.h> #include "libavformat/avformat.h" #include "libavutil/time.h" #include "libavutil/mathematics.h"#define RTMP_ADDR "rtmp://127.0.0.1:1935/live/1234"void fix_packet_pts(AVPacket *packet, AVRational timebase, int frame_index) {// 两帧之间的持续时间// r_frame_rate = (AVRational) {den , num}, 与time_base结构相反AVRational in_frame_rate = {timebase.num,timebase.den,};int64_t calc_duration = (double)AV_TIME_BASE / av_q2d(in_frame_rate); //in_stream->r_frame_ratepacket->pts = (double)(frame_index * calc_duration) / (double)(av_q2d(timebase)*AV_TIME_BASE);packet->dts = packet->pts;packet->duration = (double)calc_duration / (double)(av_q2d(timebase)*AV_TIME_BASE); }void send_rtmp(const char *file) {// 输入AVFormatContext *ifmt_ctx = NULL;if (avformat_open_input(&ifmt_ctx, file, 0, 0) < 0) {printf("failed to open input file\n");goto _Error;}if (avformat_find_stream_info(ifmt_ctx, 0) < 0) {printf("failed to find stream info\n");goto _Error;}int video_idx = -1; video_idx = av_find_best_stream(ifmt_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, NULL, 0);if (video_idx < 0) {printf("failed to find stream_index\n");goto _Error;}av_dump_format(ifmt_ctx, 0, file, 0);// 输出AVFormatContext *ofmt_ctx = NULL;if (avformat_alloc_output_context2(&ofmt_ctx, NULL, "flv", RTMP_ADDR) < 0) {printf("failed to alloc output context\n");goto _Error;}int out_stm_idx = -1;for (int i = 0; i < ifmt_ctx->nb_streams; i++) { AVStream *in_stream = ifmt_ctx->streams[i];AVStream *out_stream = avformat_new_stream(ofmt_ctx, NULL);avcodec_parameters_copy(out_stream->codecpar, in_stream->codecpar);out_stream->codecpar->codec_tag = 0;//if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER) {// out_stream->codecpar->flags |= CODEC_FLAG_GLOBAL_HEADER;//}}av_dump_format(ofmt_ctx, 0, RTMP_ADDR, 1);// open output urlif (!(ofmt_ctx->oformat->flags & AVFMT_NOFILE)) {if (avio_open(&ofmt_ctx->pb, RTMP_ADDR, AVIO_FLAG_WRITE) < 0) {printf("failed to open output url:%s\n", RTMP_ADDR);goto _Error;}}if (avformat_write_header(ofmt_ctx, NULL) < 0) {printf("failed to write header\n");goto _Error;}int frame_index = 0;int64_t start_time = av_gettime();AVPacket *packet = av_packet_alloc();while (1) {if (av_read_frame(ifmt_ctx, packet) < 0) break;// raw h264, doesn't contain pts// 如果实际推流的是flv文件，不会执行里面的fix_packet_ptsif (packet->pts == AV_NOPTS_VALUE) {fix_packet_pts(packet, ifmt_ctx->streams[video_idx]->time_base, frame_index); }// important delayif (packet->stream_index == video_idx) {AVRational timebase = ifmt_ctx->streams[video_idx]->time_base;AVRational timebase_q = {1, AV_TIME_BASE};int64_t pts_time = av_rescale_q(packet->pts, timebase, timebase_q);int64_t now_time = av_gettime() - start_time;if (pts_time > now_time) av_usleep(pts_time - now_time);}// rescale time baseav_packet_rescale_ts(packet, ifmt_ctx->streams[packet->stream_index]->time_base, \ofmt_ctx->streams[packet->stream_index]->time_base);packet->pos = -1;if (packet->stream_index == video_idx) {printf("send %6d video frames to output url\n", frame_index);frame_index++;}if (av_interleaved_write_frame(ofmt_ctx, packet) < 0) {printf("failed to write frame to url\n");break;}av_packet_unref(packet);}av_write_trailer(ofmt_ctx);_Error:if (ifmt_ctx) {avformat_close_input(&ifmt_ctx);}if (ofmt_ctx) {if (!(ofmt_ctx->oformat->flags & AVFMT_NOFILE)) avio_close(ofmt_ctx->pb);avformat_free_context(ofmt_ctx);}if (packet) av_packet_free(&packet); }int main(int argc, char const* argv[]) {send_rtmp(argv[1]); return 0; }

测试运行：

出现了一个警告，如下图。大致原因就是找不到视频的时长和文件大小信息，我们不理会也是没有问题的。

实际用ffmpeg命令推流时也会遇到这个问题，ffmpeg -re -i ../../testvideo/chinese_partner.flv -vcodec libx264 -f flv rtmp://127.0.0.1:1935/live/1234

可以添加-flvflags no_duration_filesize 参数，让ffmpeg不要抛出duration_filesize警告。

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