package com.inspect.tcpserver.sip.gb28181;

import java.net.*;
import java.util.concurrent.atomic.AtomicInteger;


public class RtpSender {
    private static final int RTP_HEADER_SIZE = 12;
    private static final int MTU = 1400;


    private final DatagramSocket socket;
    private final InetAddress remote;
    private final int port;
    private final int ssrc;
    private final AtomicInteger seq = new AtomicInteger(0);
    private int timestamp = 0;


    public RtpSender(DatagramSocket socket, InetAddress remote, int port, int ssrc) {
        this.socket = socket;
        this.remote = remote;
        this.port = port;
        this.ssrc = ssrc;
    }


    public void send(byte[] ps, boolean marker) throws Exception {
        int offset = 0;
        while (offset < ps.length) {

            int size = Math.min(MTU, ps.length - offset);
            byte[] pkt = new byte[RTP_HEADER_SIZE + size];


            pkt[0] = (byte) 0x80;
            pkt[1] = (byte) (96 | (marker ? 0x80 : 0x00));
            pkt[2] = (byte) (seq.get() >> 8);
            pkt[3] = (byte) (seq.getAndIncrement());


            timestamp += 3600;
            pkt[4] = (byte) (timestamp >> 24);
            pkt[5] = (byte) (timestamp >> 16);
            pkt[6] = (byte) (timestamp >> 8);
            pkt[7] = (byte) (timestamp);


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


            System.arraycopy(ps, offset, pkt, RTP_HEADER_SIZE, size);
            socket.send(new DatagramPacket(pkt, pkt.length, remote, port));
            offset += size;
        }
    }
}