将H264码流打包成RTP包

// 申请一块内存用于存储rtp包数据，初始化rtp包头
struct RTP_PACKET_S * rtpPacket = (RTP_PACKET_S *)malloc(500000); 
rtpHeaderInit(rtpPacket, 0, 0, 0, RTP_VERSION, RTP_PAYLOAD_TYPE_H264, 0, 0, 0, 0x88923423);
// 创建套接字
rtpServerSockfd = socket(AF_INET, SOCK_DGRAM, 0);
// 打开h.264文件
int fd = open(argv[1], O_RDONLY);
// 申请内存用于读取h.264文件内容
uint8_t * frame = (uint8_t*)malloc(500000);
while(1)
{
  // 读取h.264文件
  readSize = read(fd, frame, 500000);
  // 找到第一个NALU数据，不包含00 00 01/00 00 00 01分隔
  getFirstNaluFrame(frame, 500000, &offset, &naluLen);
  // 处理并发送NALU数据
  rtpSendH264Frame(rtpServerSockfd, CLIENT_IP, CLIENT_PORT, rtpPacket, frame + offset, naluLen);
  // 移动文件读写位置到下一个NALU起始处
  lseek(fd, fd_Lseek, SEEK_SET );
  // 发送完一包NALU后，根据帧率计算延时
  usleep(1000*1000/FPS);
}
// rtpSendH264Frame函数分析
static int rtpSendH264Frame(int rtpSockfd, char * ip, int16_t port, struct RTP_PACKET_S * rtpPacket, uint8_t * naluFrame, int naluLen)
{
  // 1.单NALU打包
    // 填充payload
    memcpy(rtpPacket->rtpPayload, naluFrame, naluLen);
    // udp发送
    sendto(rtpSockfd, (void*)rtpPacket, naluLen + RTP_HEADER_SIZE, 0, (struct sockaddr *)&addr, sizeof(addr));
  // 2.分片打包
    // 计算完整包个数和最后一包剩余字节数
    int packetNum = naluLen / RTP_MAX_PKT_SIZE; // 有几个完整的包
    int lastRemainSize = naluLen % RTP_MAX_PKT_SIZE; // 最后一包剩余的字节数
    for(int i = 0; i < packetNum; i++) // 发送所有整包
    {
      // 分片发送是payoad前需加2字节的数据,具体见"4.将H264码流打包成RTP包.md"
      rtpPacket->rtpPayload[0]
      rtpPacket->rtpPayload[1]
      // 填充payload
      memcpy(rtpPacket->rtpPayload+2, naluFrame+pos, RTP_MAX_PKT_SIZE);
      // udp发送
      sendto(rtpSockfd, rtpPacket, RTP_HEADER_SIZE+RTP_MAX_PKT_SIZE+2, 0, (struct sockaddr *)&addr, sizeof(addr));
    }
    if(lastRemainSize > 0) // 发送剩余的数据
    {
      // 分片发送是payoad前需加2字节的数据,具体见"4.将H264码流打包成RTP包.md"
      rtpPacket->rtpPayload[0]
      rtpPacket->rtpPayload[1]
      // 填充payload
      memcpy(rtpPacket->rtpPayload+2, naluFrame+pos, lastRemainSize+2);
      // udp发送
      sendto(rtpSockfd, (void*)rtpPacket, RTP_HEADER_SIZE+lastRemainSize+2, 0, (struct sockaddr *)&addr, sizeof(addr));
    }
}