//class RTPpacket
public class RTPpacket{
//size of the RTP header:
static int HEADER_SIZE = 12;
//Fields that compose the RTP header
public int Version;
public int Padding;
public int Extension;
public int CC;
public int Marker;
public int PayloadType;
public int SequenceNumber;
public int TimeStamp;
public int Ssrc;
//Bitstream of the RTP header
public byte[] header;
//size of the RTP payload
public int payload_size;
//Bitstream of the RTP payload
public byte[] payload;
//--------------------------
//Constructor of an RTPpacket object from header fields and payload bitstream
//--------------------------
public RTPpacket(int PType, int Framenb, int Time, byte[] data, int data_length){
//fill by default header fields:
Version = 2;
Padding = 0;
Extension = 0;
CC = 0;
Marker = 0;
Ssrc = 0;
//fill changing header fields:
SequenceNumber = Framenb;
TimeStamp = Time;
PayloadType = PType;
//build the header bistream:
//--------------------------
header = new byte[HEADER_SIZE];
//.............
//TO COMPLETE
//.............
//fill the header array of byte with RTP header fields
//header[0] = ...
// .....
//fill the payload bitstream:
//--------------------------
payload_size = data_length;
payload = new byte[data_length];
//fill payload array of byte from data (given in parameter of the constructor)
//......
// ! Do not forget to uncomment method printheader() below !
}
//--------------------------
//Constructor of an RTPpacket object from the packet bistream
//--------------------------
public RTPpacket(byte[] packet, int packet_size)
{
//fill default fields:
Version = 2;
Padding = 0;
Extension = 0;
CC = 0;
Marker = 0;
Ssrc = 0;
//check if total packet size is lower than the header size
if (packet_size >= HEADER_SIZE)
{
//get the header bitsream:
header = new byte[HEADER_SIZE];
for (int i=0; i < HEADER_SIZE; i++)
header[i] = packet[i];
//get the payload bitstream:
payload_size = packet_size - HEADER_SIZE;
payload = new byte[payload_size];
for (int i=HEADER_SIZE; i < packet_size; i++)
payload[i-HEADER_SIZE] = packet[i];
//interpret the changing fields of the header:
PayloadType = header[1] & 127;
SequenceNumber = unsigned_int(header[3]) + 256*unsigned_int(header[2]);
TimeStamp = unsigned_int(header[7]) + 256*unsigned_int(header[6]) + 65536*unsigned_int(header[5]) + 16777216*unsigned_int(header[4]);
}
}
//--------------------------
//getpayload: return the payload bistream of the RTPpacket and its size
//--------------------------
public int getpayload(byte[] data) {
for (int i=0; i < payload_size; i++)
data[i] = payload[i];
return(payload_size);
}
//--------------------------
//getpayload_length: return the length of the payload
//--------------------------
public int getpayload_length() {
return(payload_size);
}
//--------------------------
//getlength: return the total length of the RTP packet
//--------------------------
public int getlength() {
return(payload_size + HEADER_SIZE);
}
//--------------------------
//getpacket: returns the packet bitstream and its length
//--------------------------
public int getpacket(byte[] packet)
{
//construct the packet = header + payload
for (int i=0; i < HEADER_SIZE; i++)
packet[i] = header[i];
for (int i=0; i < payload_size; i++)
packet[i+HEADER_SIZE] = payload[i];
//return total size of the packet
return(payload_size + HEADER_SIZE);
}
//--------------------------
//gettimestamp
//--------------------------
public int gettimestamp() {
return(TimeStamp);
}
//--------------------------
//getsequencenumber
//--------------------------
public int getsequencenumber() {
return(SequenceNumber);
}
//--------------------------
//getpayloadtype
//--------------------------
public int getpayloadtype() {
return(PayloadType);
}
//--------------------------
//print headers without the SSRC
//--------------------------
public void printheader()
{
//TO DO: uncomment
/*
for (int i=0; i < (HEADER_SIZE-4); i++)
{
for (int j = 7; j>=0 ; j--)
if (((1<= 0)
return(nb);
else
return(256+nb);
}
}