美文网首页IOS多媒体
iOS:FFmpeg学习笔记(三)--数据

iOS:FFmpeg学习笔记(三)--数据

作者: 风与鸾 | 来源:发表于2017-10-31 15:15 被阅读204次

    本文介绍网络协议数据的处理程序。网络协议数据在视频播放器中的位置如下所示。



    本文中的程序是一个UDP/RTP协议流媒体数据解析器。该程序可以分析UDP协议中的RTP 包头中的内容,以及RTP负载中MPEG-TS封装格式的信息。通过修改该程序可以实现不同的UDP/RTP协议数据处理功能。原理
    MPEG-TS封装格式数据打包为RTP/UDP协议然后发送出去的流程如下图所示。图中首先每7个MPEG-TS Packet打包为一个RTP,然后每个RTP再打包为一个UDP。其中打包RTP的方法就是在MPEG-TS数据前面加上RTP Header,而打包RTP的方法就是在RTP数据前面加上UDP Header。



    有关MPEG-TS、RTP、UDP的知识不再详细介绍,可以参考相关的文档了解其中的细节信息。本文记录的程序是一个收取流媒体的程序,因此本文程序的流程和上述发送MPEG-TS的流程正好是相反的。该程序可以通过Socket编程收取UDP包,解析其中的RTP包的信息,然后再解析RTP包中MPEG-TS Packet的信息。
    #include <stdio.h>  
    #include <winsock2.h>  
      
    #pragma comment(lib, "ws2_32.lib")   
      
    #pragma pack(1)  
      
    /* 
     * [memo] FFmpeg stream Command: 
     * ffmpeg -re -i sintel.ts -f mpegts udp://127.0.0.1:8880 
     * ffmpeg -re -i sintel.ts -f rtp_mpegts udp://127.0.0.1:8880 
     */  
      
    typedef struct RTP_FIXED_HEADER{  
        /* byte 0 */  
        unsigned char csrc_len:4;       /* expect 0 */  
        unsigned char extension:1;      /* expect 1 */  
        unsigned char padding:1;        /* expect 0 */  
        unsigned char version:2;        /* expect 2 */  
        /* byte 1 */  
        unsigned char payload:7;  
        unsigned char marker:1;        /* expect 1 */  
        /* bytes 2, 3 */  
        unsigned short seq_no;              
        /* bytes 4-7 */  
        unsigned  long timestamp;          
        /* bytes 8-11 */  
        unsigned long ssrc;            /* stream number is used here. */  
    } RTP_FIXED_HEADER;  
      
    typedef struct MPEGTS_FIXED_HEADER {  
        unsigned sync_byte: 8;   
        unsigned transport_error_indicator: 1;   
        unsigned payload_unit_start_indicator: 1;  
        unsigned transport_priority: 1;   
        unsigned PID: 13;  
        unsigned scrambling_control: 2;  
        unsigned adaptation_field_exist: 2;  
        unsigned continuity_counter: 4;  
    } MPEGTS_FIXED_HEADER;  
      
      
      
    int simplest_udp_parser(int port)  
    {  
        WSADATA wsaData;  
        WORD sockVersion = MAKEWORD(2,2);  
        int cnt=0;  
      
        //FILE *myout=fopen("output_log.txt","wb+");  
        FILE *myout=stdout;  
      
        FILE *fp1=fopen("output_dump.ts","wb+");  
      
        if(WSAStartup(sockVersion, &wsaData) != 0){  
            return 0;  
        }  
      
        SOCKET serSocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);   
        if(serSocket == INVALID_SOCKET){  
            printf("socket error !");  
            return 0;  
        }  
      
        sockaddr_in serAddr;  
        serAddr.sin_family = AF_INET;  
        serAddr.sin_port = htons(port);  
        serAddr.sin_addr.S_un.S_addr = INADDR_ANY;  
        if(bind(serSocket, (sockaddr *)&serAddr, sizeof(serAddr)) == SOCKET_ERROR){  
            printf("bind error !");  
            closesocket(serSocket);  
            return 0;  
        }  
      
        sockaddr_in remoteAddr;  
        int nAddrLen = sizeof(remoteAddr);   
      
        //How to parse?  
        int parse_rtp=1;  
        int parse_mpegts=1;  
      
        printf("Listening on port %d\n",port);  
      
        char recvData[10000];    
        while (1){  
      
            int pktsize = recvfrom(serSocket, recvData, 10000, 0, (sockaddr *)&remoteAddr, &nAddrLen);  
            if (pktsize > 0){  
                //printf("Addr:%s\r\n",inet_ntoa(remoteAddr.sin_addr));  
                //printf("packet size:%d\r\n",pktsize);  
                //Parse RTP  
                //  
                if(parse_rtp!=0){  
                    char payload_str[10]={0};  
                    RTP_FIXED_HEADER rtp_header;  
                    int rtp_header_size=sizeof(RTP_FIXED_HEADER);  
                    //RTP Header  
                    memcpy((void *)&rtp_header,recvData,rtp_header_size);  
      
                    //RFC3551  
                    char payload=rtp_header.payload;  
                    switch(payload){  
                    case 0:  
                    case 1:  
                    case 2:  
                    case 3:  
                    case 4:  
                    case 5:  
                    case 6:  
                    case 7:  
                    case 8:  
                    case 9:  
                    case 10:  
                    case 11:  
                    case 12:  
                    case 13:  
                    case 14:  
                    case 15:  
                    case 16:  
                    case 17:  
                    case 18: sprintf(payload_str,"Audio");break;  
                    case 31: sprintf(payload_str,"H.261");break;  
                    case 32: sprintf(payload_str,"MPV");break;  
                    case 33: sprintf(payload_str,"MP2T");break;  
                    case 34: sprintf(payload_str,"H.263");break;  
                    case 96: sprintf(payload_str,"H.264");break;  
                    default:sprintf(payload_str,"other");break;  
                    }  
      
                    unsigned int timestamp=ntohl(rtp_header.timestamp);  
                    unsigned int seq_no=ntohs(rtp_header.seq_no);  
      
                    fprintf(myout,"[RTP Pkt] %5d| %5s| %10u| %5d| %5d|\n",cnt,payload_str,timestamp,seq_no,pktsize);  
      
                    //RTP Data  
                    char *rtp_data=recvData+rtp_header_size;  
                    int rtp_data_size=pktsize-rtp_header_size;  
                    fwrite(rtp_data,rtp_data_size,1,fp1);  
      
                    //Parse MPEGTS  
                    if(parse_mpegts!=0&&payload==33){  
                        MPEGTS_FIXED_HEADER mpegts_header;  
                        for(int i=0;i<rtp_data_size;i=i+188){  
                            if(rtp_data[i]!=0x47)  
                                break;  
                            //MPEGTS Header  
                            //memcpy((void *)&mpegts_header,rtp_data+i,sizeof(MPEGTS_FIXED_HEADER));  
                            fprintf(myout,"   [MPEGTS Pkt]\n");  
                        }  
                    }  
      
                }else{  
                    fprintf(myout,"[UDP Pkt] %5d| %5d|\n",cnt,pktsize);  
                    fwrite(recvData,pktsize,1,fp1);  
                }  
      
                cnt++;  
            }  
        }  
        closesocket(serSocket);   
        WSACleanup();  
        fclose(fp1);  
      
        return 0;  
    }  
    
    调用: simplest_udp_parser(8880);  
    

    相关文章

      网友评论

        本文标题:iOS:FFmpeg学习笔记(三)--数据

        本文链接:https://www.haomeiwen.com/subject/mfybpxtx.html