package com.inspect.tcpserver.sip.media;

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;

public class RtpSender {

    private DatagramSocket socket;
    private InetAddress address;
    private int port;
    private int seq = 0;
    private long timestamp = 0;
    private int ssrc;

    public RtpSender(String ip, int port, int ssrc) throws Exception {
        this.socket = new DatagramSocket();
        this.address = InetAddress.getByName(ip);
        this.port = port;
        this.ssrc = ssrc;
    }

    public void send(byte[] payload, boolean mark) throws Exception {
        byte[] rtp = new byte[12 + payload.length];

        rtp[0] = (byte) 0x80;
        rtp[1] = (byte) (96 | (mark ? 0x80 : 0));

        rtp[2] = (byte) (seq >> 8);
        rtp[3] = (byte) (seq);
        seq++;

        timestamp += 3600; // 90k时钟
        rtp[4] = (byte) (timestamp >> 24);
        rtp[5] = (byte) (timestamp >> 16);
        rtp[6] = (byte) (timestamp >> 8);
        rtp[7] = (byte) (timestamp);

        rtp[8] = (byte) (ssrc >> 24);
        rtp[9] = (byte) (ssrc >> 16);
        rtp[10] = (byte) (ssrc >> 8);
        rtp[11] = (byte) (ssrc);

        System.arraycopy(payload, 0, rtp, 12, payload.length);

        socket.send(new DatagramPacket(rtp, rtp.length, address, port));
    }
}