rtsp跟http一樣都是七層應(yīng)用層協(xié)議.在rtsp協(xié)議組中的主要作用是:




１．客戶端發(fā)送OPTIONS請求：

客戶端(ffplay)請求報文:
OPTIONS rtsp://127.0.0.1:1133 RTSP/1.0\r\nCSeq: 1\r\nUser-Agent: Lavf57.83.100\r\n\r\n}$
服務(wù)端響應(yīng)報文：
RTSP/1.0 200 OK\r\nCSeq:"+QString::number(cseq)+"\r\nPublic:DESCRIBE, SETUP, TEARDOWN, PLAY, PAUSE\r\n\r\n
//服務(wù)器返回了服務(wù)器支持的方法;
//注意請求和返回都是\r\n\r\n結(jié)尾。

２．客戶端發(fā)送DESCRIBE請求

客戶端發(fā)送DESCRIBE請求
DESCRIBE rtsp://127.0.0.1:1133 RTSP/1.0\r\nAccept:　application/sdp\r\nCSeq: 2\r\nUser-Agent: Lavf57.83.100\r\n\r\n"
服務(wù)端響應(yīng)客戶端請求．
"c=IN IP4 127.0.0.1\r\nm=video 0 RTP/AVP 96\r\na=rtpmap:96 H265/90000\r\na=fmtp:96 profile-space=0;profile-id=0;tier-flag=0;level-id=0\r\n\r\n"
//注釋：a=rtpmap:96 H265/90000 　96表示媒體類型是視頻，H265/90000表示h265編碼波特率是90000

３.客戶端SETUP請求：

客戶端setup請求報文
"SETUP rtsp://127.0.0.1:1133 RTSP/1.0\r\nTransport: RTP/AVP/UDP;unicast;client_port=\r\nCSeq: 3\r\nUser-Agent: Lavf57.83.100\r\n\r\n"
//紅色為客戶端監(jiān)聽的端口號．
服務(wù)端響應(yīng)報文
"RTSP/1.0 200 OK\r\nCSeq:0\r\nTransport: RTP/AVP;unicast;client_port=18174-0;server_port=;ssrc=\r\nSession:\r\n\r\n"
//紅色部分為server rtp-rtcp端口號，藍(lán)色部分和綠色部分為會話唯一標(biāo)識，類似于http的會話保持．

４．客戶端發(fā)送PLAY請求

客戶端PLAY請求報文
"PLAY rtsp://127.0.0.1:1133 RTSP/1.0\r\nRange: npt=0.000-\r\nCSeq: 4\r\nUser-Agent: Lavf57.83.100\r\nSession: Wang_qin_feng18174_0\r\n\r\n"
服務(wù)端返回報文
"RTSP/1.0 200 OK\r\nCSeq: 0\r\nSession:Wang_qin_feng10540_0\r\nRTP-Info: url=rtsp://127.0.0.1:1133;seq=9810092;rtptime=0\r\n\r\n"

5.此時ffplay等待server rtp端口號(1130)發(fā)送來的數(shù)據(jù)．
rtsp的實現(xiàn)：
cache.h全局緩存

#ifndef CACHE_H
#define CACHE_H
#include <QList>
#include <QHostAddress>
#include "rtp.h"
struct rtp_rtcp_struct{
  int rtp; //客戶端端口
  int rtcp;　//客戶端端口
  QHostAddress ip;　//客戶端地址
};
extern rtp_rtcp_struct s_s_p;
extern QList<rtp_rtcp_struct> client_rtp_rtcp_list;
extern rtp rtp_server;
class cache
{
public:
    cache();
};

#endif // CACHE_H

cache.cpp

#include "cache.h"
#include <QList>

rtp_rtcp_struct s_s_p;
QList<rtp_rtcp_struct> client_rtp_rtcp_list;
rtp rtp_server;
cache::cache()
{

}

rtsp.h

#define RTSP_H
#include <QObject>
#include <QTcpServer>
#include <QTcpSocket>
class rtsp : public QTcpServer
{
    Q_OBJECT
public:
    explicit rtsp(int rtp,int rtcp,QTcpServer *parent = nullptr);
    void incomingConnection(qintptr socket_number);
signals:
public slots:
private:
    int server_rtp;
    int server_rtcp;
};
//客戶端連接
class connect_socket :public QTcpSocket{
    Q_OBJECT
public:
    explicit connect_socket(int rtp,int rtcp,qintptr 　　socket_number,QTcpSocket *parent=nullptr);
    enum return_error{
        no_error=0,
        no_vision= -1,
        no_rtp_rtcp_port=-2,
    };
signals:
private:
    int router(QStringList head); //請求方法路由
    void send_methon();    //返回支持的方法
    void send_rtp_rtcp_session();　//返回會話端口號等信息
    void send_sdp();    //發(fā)送sdp文件
    int verison;
    int client_rtp_port;　//client 監(jiān)聽rtp的端口號
    int client_rtcp_port; //client 監(jiān)聽的rtcp的端口號
    int server_rtp_port;　
    int server_rtcp_port;
    int cseq=0;
    QByteArray SSRC="Wang_qin_feng";
public slots:
    void read_data();
};
#endif // RTSP_H

rtsp.cpp

#include "rtsp.h"
#include <QTcpServer>
#include <QTcpSocket>
#include <QThread>
#include <QDebug>
#include <QDateTime>
#include <QByteArray>
#include "cache.h"
rtsp::rtsp(int rtp,int rtcp,QTcpServer *parent) : QTcpServer(parent)
{
    server_rtp=rtp; 
    server_rtcp=rtcp;
}
//新的tcp socket連接時創(chuàng)建一個新的連接．
void rtsp::incomingConnection(qintptr socket_number){
　//new一個新的socket連接
    connect_socket *client_socket=new　connect_socket(server_rtp,server_rtcp,socket_number);
 //創(chuàng)建一個線程．
    QThread *client_socket_thread=new QThread();
    client_socket->moveToThread(client_socket_thread);
    client_socket_thread->start();
}
connect_socket::connect_socket(int rtp,int rtcp,qintptr socket_number,QTcpSocket *parent):QTcpSocket (parent){
    this->setSocketDescriptor(socket_number);
    server_rtp_port=rtp; //server rtp_port
    server_rtcp_port=rtcp; //server rtcp_port
//有數(shù)據(jù)傳入是調(diào)用槽
    connect(this,SIGNAL(readyRead()),this,SLOT(read_data()));
};
void connect_socket::read_data(){　
    QString tmp_data;
    tmp_data=this->readAll();
    if(tmp_data.size()>50){　//因為vlc有傳空請求來！所有判定下長度
        QStringList request_body=tmp_data.split(" ");
//        qDebug()<<tmp_data;
      //按不同的請求路由到不同的處理方法．
        router(request_body);
    }
}
int connect_socket::router(QStringList head){
    return_error error_return;
    error_return=no_error; //正常返回0;
    QString methon=head[0];

    cseq=head[3].split("\r\n")[0].toInt();
    if(methon=="OPTIONS"){ //本版獲取
        error_return=no_vision;
            if(head[2].contains("\r\n")){
                QStringList verison_list=head[2].split("\r\n");
                //rtsp獲取版本號
                if(verison_list[0].contains("/")){verison=verison_list[0].split("/")[0].toInt();}else {
                    return  error_return;
                    };
                send_methon(); //發(fā)送支持的方法給客戶端;
            }else {
                //無版本號返回-1;
                error_return=no_vision;
                return error_return;
            }
    }else if (methon=="SETUP") { //setup請求
        error_return=no_rtp_rtcp_port;
        //從請求中取出rtp rtcp端口號
        if(head[head.length()-1].contains("\r\n\r\n")){
            int client_port_index=0;
            for(int i=0;i<head.length();i++){
                if(head[i].contains("=") and head[i].contains("-")){
                    client_port_index=i;
                }
            }
            QStringList port_list=head[client_port_index].split("\r\n\r\n")[0].split("=")[1].split("-");
            client_rtp_port=port_list[0].toInt();
            client_rtcp_port=port_list[1].toInt();
                        //添加客戶端端口號到列表
            s_s_p.rtp=client_rtp_port;
            s_s_p.rtcp=client_rtcp_port;
            s_s_p.ip= this->peerAddress();
            client_rtp_rtcp_list.append(s_s_p);
                        //返回會話數(shù)據(jù)
            send_rtp_rtcp_session();
            }else {
                        return error_return;
                    }
    }else if (methon=="PLAY") {
        QString url;
        if(head.size()>=1){
            url=head[1];
        }
        QByteArray data;
        data.append("RTSP/1.0 200 OK\r\nCSeq: "+QString::number(cseq)+"\r\nSession: "+SSRC+"\r\n"+"RTP-Info: url="+url
                    +";seq=9810092;rtptime=0\r\n\r\n");
        this->write(data);
//        qDebug()<<data;
        this->waitForBytesWritten(3000);
    }else if (methon=="DESCRIBE") {
            send_sdp();
    }else{
    }
    return  error_return;
};
void connect_socket::send_methon(){ //發(fā)送支持的方法
    QByteArray data;
    data.append("RTSP/1.0 200 OK\r\n CSeq:"+QString::number(cseq)+"\r\nPublic:DESCRIBE, SETUP, TEARDOWN, PLAY, PAUSE\r\n\r\n");
    this->write(data);
    this->waitForBytesWritten(3000);
}
void connect_socket::send_rtp_rtcp_session(){ //發(fā)送會話數(shù)據(jù)
    SSRC+=QString::number(client_rtp_port)+"_"+QString::number(client_rtcp_port);
    QByteArray data;
    data.append("RTSP/1.0 200 OK\r\nCSeq:"+QString::number(cseq)+"\r\nTransport: RTP/AVP;unicast;client_port="+
            QString::number(client_rtp_port)+"-"+QString::number(client_rtcp_port)+";"
            +"server_port="+QString::number(server_rtp_port)+"-"+QString::number(server_rtcp_port)+";"
            +"ssrc="+SSRC+"\r\nSession:"+SSRC+"\r\n\r\n");
//    qDebug()<<data;
    this->write(data);
    this->waitForBytesWritten(3000);
}
void connect_socket::send_sdp(){
    QByteArray tmp_data;
    QByteArray data;
    tmp_data.append("c=IN IP4 "+this->peerAddress().toString().split(":")[3]+"\r\nm=video 0 RTP/AVP 96\r\na=rtpmap:96 H265/90000\r\na=fmtp:96 profile-space=0;profile-id=0;tier-flag=0;level-id=0\r\n\r\n");
    data.append( "RTSP/1.0 200 OK\r\nCSeq:"+QString::number(cseq)+"\r\nContent-Type: application/sdp\r\nContent-Length:"
                 +QString::number(tmp_data.size())+"\r\n\r\n");
    data.append(tmp_data);
//    qDebug()<<tmp_data;
    this->write(data);
    this->waitForBytesWritten(3000);
}