Java UDP send - receive packet one by one

Question

I'm trying to send and receive some Audio encoded data via UDP, and confused.

First of all, I have done UDP send-receive before on C# and node.js, and receiving the packet one by one is very straight forward and easy, but it's different in Java, and confusing me.

The every encoded data size is approximately 360-380 bytes for each,

and I need to send this encoded data as a packet to remote(or localhost so far) via UDP.

The UDP-receiver should receive the encoded data as a packet and process to decode.

Here is a brief example to illustrate what I do.

Encoder and UDP-sender

  ds = new DatagramSocket(localPort);
  //a Thread with While loop----------
  Log.d("AudioEncoder", outData.length + " bytes encoded");
  //The encoded data size is about 370 bytes for each

  packet = new DatagramPacket(outData, outData.length,
  InetAddress.getByName("127.0.0.1"), localPort);
  ds.send(packet);

UDP-receiver and Decoder

ds = new DatagramSocket(localPort);
byte[] buffer2 = new byte[1024];
DatagramPacket packet = new DatagramPacket(buffer2, buffer2.length);

while (isPlaying)
{
        ds.receive(packet); 
        Log.d("UDP-receiver",  buffer2.length + " bytes received");

        //do Decoding on buffer2
        //..........
}

Basically, a packet (encoded byte data) size to send and receive is approximately 360-380 bytes for each.

Then, I understand for Java Datagram, make a buffer for a specific byte size such as 512 or 1024 (I don't know what size is most optimized in this case, and in these days).

If I set the DatagramPacket size 1024 bytes, the packet which size is 360-380 bytes comes twice to be pooled in the buffer, then the original 2 packets are joind together then processed as a single byte array?

If I set the DatagramPacket size 512 bytes, the packet which size is 360-380 bytes comes twice to be pooled in the buffer, then since it's overflowed the buffer size, the single packet arrived is swiped to be processed?

Again, it's sufficient at least, the receiver can receive a packet one by one, then process for each, but things looks complicated here.

Please instruct me . Thanks.

user207421 user207421 · Accepted Answer · 2014-02-18T22:32:05

If I set the DatagramPacket size 1024 bytes, the packet which size is 360-380 bytes comes twice to be pooled in the buffer, then the original 2 packets are joind together then processed as a single byte array?

No. You receive two separate packets.

If I set the DatagramPacket size 512 bytes, the packet which size is 360-380 bytes comes twice to be pooled in the buffer

No.

then since it's overflowed the buffer size, the single packet arrived is swiped to be processed?

I don't know what 'swiped' means, but none of this happens. You receive two separate packets.

Java UDP send - receive packet one by one

1 Answers