利用ffmpeg从RTSP服务器拉流并保存各种格式文件

Love The Way You Lie 2023-10-16 12:49 6阅读 0赞

*  增加命令的选项：
    
     *  RTSP url
     *  视频文件保存格式
     *  要保存的帧数
     *  第一帧是I帧

废话少说，上代码：

#include<stdio.h>
    #include<libavformat/avformat.h>
    #include<libavutil/mathematics.h>
    #include<libavutil/time.h>
    #include <unistd.h>
    
    #define USAGE   "rtsp2x -i <rtsp url> -t [avi | flv | mp4] -n <number of frames you want to save>"
    #define OPTS    "i:t:n:h"
    
    static void print_usage()
    {
            printf("Usage: %s\n", USAGE);
            return;
    }
    int main(int argc,char **argv)
    {
            AVOutputFormat *ofmt = NULL;
        AVFormatContext *ifmt_ctx = NULL,*ofmt_ctx = NULL;
        AVPacket pkt;
        const char in_filename[128] = {0}, out_filename[128] = {0};    
        int ret,i;
        int video_index=-1;
        int frame_index=0;
            int I_received = 0;
    
            int opt, frames_count = -1;
    
            while ((opt = getopt(argc, argv, OPTS)) != -1) {
                    switch (opt) {
                    case 'i':
                            strcpy(in_filename, optarg);
                            break;
                    case 't':
                            if (strcmp(optarg, "avi") == 0)
                                    strcpy(out_filename, "receive.avi");
                            else if (strcmp(optarg, "flv") == 0)
                                    strcpy(out_filename, "receive.flv");
                            else if (strcmp(optarg, "mp4") == 0) 
                                    strcpy(out_filename, "receive.mp4");
                            else {
                                    return -1;
                            }
                            print_usage();
                            break;
                    case 'n':
                            frames_count = atoi(optarg);
                            if (frames_count < 0) {
                                    print_usage();
                                    return -1;
                            }
                            printf("frames_count = %d\n", frames_count);
                            break;
                    case 'h':
                    default:
                            print_usage();
                            return -1;
                    }
            }
    
            if (strlen(in_filename) == 0 || strlen(out_filename) == 0 || frames_count < 0) {
                    print_usage();
                    return -1;
            }
    
        av_register_all();
        avformat_network_init();
    
        //使用TCP连接打开RTSP，设置最大延迟时间
        AVDictionary *avdic=NULL;  
        char option_key[]="rtsp_transport";  
        char option_value[]="tcp";  
        av_dict_set(&avdic,option_key,option_value,0);  
        char option_key2[]="max_delay";  
        char option_value2[]="5000000";  
        av_dict_set(&avdic,option_key2,option_value2,0); 
        //打开输入流
        if((ret=avformat_open_input(&ifmt_ctx,in_filename,0,&avdic))<0)
        {
            printf("Could not open input file.\n");
            goto end;
        }
        if((ret=avformat_find_stream_info(ifmt_ctx,0))<0)
        {
            printf("Failed to retrieve input stream information\n");
            goto end;
        }
        //nb_streams代表有几路流，一般是2路：即音频和视频，顺序不一定
        for(i=0;i<ifmt_ctx->nb_streams;i++){
            
            if(ifmt_ctx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO)
            {
                //这一路是视频流，标记一下，以后取视频流都从ifmt_ctx->streams[video_index]取
                video_index=i;
                break;
            }
        }
    
        av_dump_format(ifmt_ctx,0,in_filename,0);
    
        //打开输出流
        avformat_alloc_output_context2(&ofmt_ctx,NULL,NULL,out_filename);
        
        if(!ofmt_ctx)
        {
            printf("Could not create output context\n");
            ret=AVERROR_UNKNOWN;
            goto end;
        }
        
        ofmt = ofmt_ctx->oformat;
        for(i=0;i<ifmt_ctx->nb_streams;i++)
        {    //根据输入流创建输出流
            AVStream *in_stream = ifmt_ctx->streams[i];
            AVStream *out_stream = avformat_new_stream(ofmt_ctx,in_stream->codec->codec);
            if(!out_stream)
            {
                printf("Failed allocating output stream.\n");
                ret = AVERROR_UNKNOWN;
                goto end;
            }
    
            //将输出流的编码信息复制到输入流
            ret = avcodec_copy_context(out_stream->codec,in_stream->codec);
            if(ret<0)
            {
                printf("Failed to copy context from input to output stream codec context\n");
                goto end;
            }
            out_stream->codec->codec_tag = 0;
        
            if(ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)
                out_stream->codec->flags |= CODEC_FLAG_GLOBAL_HEADER;
    
        }
    
        //Dump format--------------------
        av_dump_format(ofmt_ctx,0,out_filename,1);
        //打开输出文件
        if(!(ofmt->flags & AVFMT_NOFILE))
        {
            ret = avio_open(&ofmt_ctx->pb,out_filename,AVIO_FLAG_WRITE);
            if(ret<0)
            {
                printf("Could not open output URL '%s'",out_filename);
                goto end;
            }
        }
    
        //写文件头到输出文件
        ret = avformat_write_header(ofmt_ctx,NULL);
        if(ret < 0)
        {
            printf("Error occured when opening output URL\n");
            goto end;
        }
    
    
        //while循环中持续获取数据包，不管音频视频都存入文件
        while(1)
        {
            AVStream *in_stream,*out_stream;
            //从输入流获取一个数据包
            ret = av_read_frame(ifmt_ctx,&pkt);
            if(ret<0)
                break;
    
            in_stream = ifmt_ctx->streams[pkt.stream_index];
            out_stream = ofmt_ctx->streams[pkt.stream_index];
            //copy packet
            //转换 PTS/DTS 时序
            pkt.pts = av_rescale_q_rnd(pkt.pts,in_stream->time_base,out_stream->time_base,(enum AVRounding)(AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX));
            pkt.dts = av_rescale_q_rnd(pkt.dts, in_stream->time_base, out_stream->time_base, (enum AVRounding)(AV_ROUND_NEAR_INF|AV_ROUND_PASS_MINMAX));  
            //printf("pts %d dts %d base %d\n",pkt.pts,pkt.dts, in_stream->time_base);
            pkt.duration = av_rescale_q(pkt.duration, in_stream->time_base, out_stream->time_base); 
            pkt.pos = -1;  
    
            //此while循环中并非所有packet都是视频帧，当收到视频帧时记录一下，仅此而已
            if(pkt.stream_index==video_index)
            {
                            if ((pkt->flags & AV_PKT_FLAG_KEY) && (I_received == 0)) 
                                    I_received = 1;
                            if (I_received == 0)
                                    continue;
    
                printf("Receive %8d video frames from input URL\n",frame_index);
                frame_index++;
            } else {
                            continue;
                    }
    
                    if (frame_index == frames_count)
                            break;
    
            //将包数据写入到文件。
            ret = av_interleaved_write_frame(ofmt_ctx,&pkt);
            if(ret < 0)
            {
                /**
                当网络有问题时，容易出现到达包的先后不一致，pts时序混乱会导致
                av_interleaved_write_frame函数报 -22 错误。暂时先丢弃这些迟来的帧吧
                若所大部分包都没有pts时序，那就要看情况自己补上时序（比如较前一帧时序+1）再写入。
                */
                if(ret==-22){
                    continue;
                }else{
                    printf("Error muxing packet.error code %d\n" , ret);
                    break;
                }
                
            }
            
            //av_free_packet(&pkt); //此句在新版本中已deprecated 由av_packet_unref代替
            av_packet_unref(&pkt);
        }
    
    
        //写文件尾
        av_write_trailer(ofmt_ctx);
    
    end:
        
        av_dict_free(&avdic);
        avformat_close_input(&ifmt_ctx);
        //Close input
        if(ofmt_ctx && !(ofmt->flags & AVFMT_NOFILE))
            avio_close(ofmt_ctx->pb);
        avformat_free_context(ofmt_ctx);
        if(ret<0 && ret != AVERROR_EOF)
        {
            printf("Error occured.\n");
            return -1;
        }
        return 0;
        
    }

编译命令：$ gcc -o rtsp2x rtsp2x.c -lavcodec -lavformat -lavutil