1.设置RTSP端口号

设置RTSP端口号的处理位于ARTSPConnection.cpp文件中，首先从url中获取端口号，如果读取不到，则设置为默认端口554。代码处理如下：

ARTSPConnection::ParseURL(

const char *colonPos = strchr(host->c_str(), ':');

if (colonPos != NULL) {

unsigned long x;

if (!ParseSingleUnsignedLong(colonPos + 1, &x) || x >= 65536) { // rtsp端口必须小于65536

return false;

}

*port = x;

size_t colonOffset = colonPos - host->c_str();

size_t trailing = host->size() - colonOffset;

host->erase(colonOffset, trailing);

} else {

*port = 554; // 如果从url中获取不到端口，则设置默认端口554

}

--------------------------------------------------------------------------------------------------------

2.设置RTP和RTCP端口号

设置RTP和RTCP端口号的处理位于ARTPConnection.cpp文件中中，与设置RTSP端口号的处理分别在不同的文件中。

(1)函数声明：创建一对相邻端口的UDP数据报套接字。rtp套接字是偶数端口，rtcp套接字端口比rtp端口号大一个号。// Creates a pair of UDP datagram sockets bound to adjacent ports

// (the rtpSocket is bound to an even port, the rtcpSocket to the

// next higher port).

static void MakePortPair(

int *rtpSocket, int *rtcpSocket, unsigned *rtpPort);

(2)函数定义：具体设置RTP和RTCP端口// static

void ARTPConnection::MakePortPair(

int *rtpSocket, int *rtcpSocket, unsigned *rtpPort) {

*rtpSocket = socket(AF_INET, SOCK_DGRAM, 0);

CHECK_GE(*rtpSocket, 0);

bumpSocketBufferSize(*rtpSocket);

*rtcpSocket = socket(AF_INET, SOCK_DGRAM, 0);

CHECK_GE(*rtcpSocket, 0);

bumpSocketBufferSize(*rtcpSocket);

unsigned start = (rand() * 1000)/ RAND_MAX + 15550; // 最小端口号为15550

start &= ~1; // 与1取反后的值做与操作，结果就是start变成偶数，端口从偶数开始

for (unsigned port = start; port < 65536; port += 2) { // rtp最大端口号为65535，此时rtcp端口号为65536

struct sockaddr_in addr;

memset(addr.sin_zero, 0, sizeof(addr.sin_zero));

addr.sin_family = AF_INET;

addr.sin_addr.s_addr = htonl(INADDR_ANY);

addr.sin_port = htons(port);

if (bind(*rtpSocket,

(const struct sockaddr *)&addr, sizeof(addr)) < 0) {

continue;

}

addr.sin_port = htons(port + 1);

if (bind(*rtcpSocket,

(const struct sockaddr *)&addr, sizeof(addr)) == 0) {

*rtpPort = port;

return; // 绑定rtcp端口后返回

}

}

TRESPASS();

}