RTCP报文解析

RTCP包的头部结构体定义

struct RTCP_Header
{
    unsigned short rc:5;
    unsigned short padding:1;
    unsigned short version:2; //1 char
    unsigned short payloadtype:8; //2 char
    unsigned short length; //3,4 char
    unsigned int ssrc; //5,6,7,8 char
};

Sender Report 类型的RTCP数据部分结构体定义

struct Rtcp_SR
{
    unsigned int  NtpTimestampMSW;
    unsigned int  NtpTimestampLSW;
    unsigned int  RtpTimestamp;
    unsigned int  SenderPacketCnt;
    unsigned int  SenderOctetCnt;
};

RTCP报文解析函数

入参：RTCP报文指针、报文字节大小

void parse_udp_packet(unsigned char* packet, int packet_length)
{
    int offset = 0;
    while (offset < packet_length)
    {
        RTCP_Header* pHeader =  (RTCP_Header*)(packet + offset);
        printf("ssrc: 0x%08x ver: %d, padding: %d, rc: %d, type: %d, paloadlen: %d\n",
            ntohl(pHeader->ssrc), pHeader->version, pHeader->padding, pHeader->rc, pHeader->payloadtype, 4 * ntohs(pHeader->length));

        if(pHeader->payloadtype == 200)
        {
            Rtcp_SR* pstSR = (Rtcp_SR*)(packet + offset + 8);

            printf("octetCnt:%d, packetCnt: %d\n",
                ntohl(pstSR->SenderOctetCnt), ntohl(pstSR->SenderPacketCnt));
        }

        offset += 4 * ntohs(pHeader->length) + 4;
    }

    return;
}