g711 RTP传输

/ g711.c
//
#include
#include
#include
#include

#include
#include
#include
#include
#include
#include
#include     //close()
#define DEST_PORT  8888
#define DEST_IP "192.168.1.18"


typedef struct
{
    /** byte 0 */
    unsigned char csrc_len:4;        /** expect 0 */
    unsigned char extension:1;       /** expect 1, see RTP_OP below */
    unsigned char padding:1;         /** expect 0 */
    unsigned char version:2;         /** expect 2 */
    /** byte 1 */
    unsigned char payload:7;         /** stream type */
    unsigned char marker:1;          /** when send the first framer,set it */
    /** 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;


int main(int argc, char* argv[])
{
    FILE *file_g711 = NULL;
    int ret;
    int M_bit;
    M_bit = 1;

    char sendbuf[1500];
    memset(sendbuf,0,1500);
    unsigned short seq_num = 0;
    RTP_FIXED_HEADER        *rtp_hdr;

    int    socket1;
    struct sockaddr_in server;
    int len = sizeof(server);
    float framerate = 25;
    unsigned int timestamp_increse = 0,ts_current = 0;
    timestamp_increse = 160;

    server.sin_family = AF_INET;
    server.sin_port = htons(DEST_PORT);
    server.sin_addr.s_addr = inet_addr(DEST_IP);
    socket1 = socket(AF_INET,SOCK_DGRAM,0);
    connect(socket1, (struct sockaddr *)&server, len) ;//申请UDP套接字

    file_g711 = fopen("test.g711","rb");
    if(file_g711 == NULL)
    {
        printf("fopen error!/n");
    }
    printf("g711 open successfully!/n");


    while((ret = fread(&sendbuf[12],sizeof(char),160,file_g711)) > 0)
    {
    rtp_hdr =(RTP_FIXED_HEADER*)&sendbuf[0];
    //设置RTP HEADER，
    rtp_hdr->payload     = 0;  //负载类型号，
    rtp_hdr->version     = 2;  //版本号，此版本固定为2
    if(1 == M_bit)
    {
            rtp_hdr->marker    = 1;   //标志位，由具体协议规定其值。
            M_bit = 0;
        printf("M_bit = 1/n");
    }
    else
    {
        rtp_hdr->marker    = 0;   //标志位，由具体协议规定其值。
    }

        rtp_hdr->ssrc        = htonl(10);    //随机指定为10，并且在本RTP会话中全局唯一

        rtp_hdr->seq_no = htons(seq_num ++);
        printf("/n/n%x/n/n",sendbuf[1]);
        ts_current = ts_current+timestamp_increse;
        rtp_hdr->timestamp=htonl(ts_current);
        printf("calloc/n");
        /**
        unsigned char *Buf;
        if ((Buf = (unsigned char*)calloc (512 , sizeof(char))) == NULL)
        {
            printf (" Could not allocate Buf memory/n");
        }
        Buf = &sendbuf[12];
        */
        /**
        ret = fread(Buf,1,511,file_g711);
        if(ret<0)
        {
            printf("fread error/n");
        }*/
        //free(Buf);
        printf("read data size is %d/n",ret);
        printf("sizeof(sendbuf) = %d",sizeof(sendbuf));

        ret = send( socket1, sendbuf, ret+12, 0 );//发送rtp包
        printf("/n/n%d/n/n",ret);
        if(ret<0)
        {
            perror("send");
            break;
        }
        printf("**********************************/n");
        printf("ret = %d/n",ret);
        printf("rtp_hdr->payload = %x/n",rtp_hdr->payload);
        printf("rtp_hdr->version = %x/n",rtp_hdr->version);
        printf("rtp_hdr->marker = %x/n",rtp_hdr->marker);
        printf("rtp_hdr->ssrc = %x/n",rtp_hdr->ssrc);
        printf("rtp_hdr->seq_no = %x/n",rtp_hdr->seq_no);
        printf("rtp_hdr->timestamp = %x/n",rtp_hdr->timestamp);
        printf("sendbuf[0]= %x/n",sendbuf[0]);
        printf("sendbuf[12]= %x/n",sendbuf[12]);
        printf("**********************************/n");

        usleep(19000);
        memset(sendbuf,0,1500);//清空sendbuf；此时会将上次的时间戳清空，因此需要ts_current来保存上次的时间戳值
    }
    fclose(file_g711);
    printf("end !!!!!!!!!!!!!!!!!!/n");
    return 0;
}

SDP文件内容：

m=audio 8888 RTP/AVP 0
a=rtpmap:8 pcmu/8000/1
a=ptime:20
c=IN IP4 192.168.1.18