VoIP with JMF

Question

hello,
i'm trying to create a J2SE VoIP app with JMF. is it feasible?
i've read that to overcome the NAT problem, we need to use Symmetry RTP. does it supported in JMF?
i've done the SIP session managing with JSIP. now i need to send and receive RTP data.
i've done this for the receiver
url= "rtp://" + IP + ":" + port + "/audio/16";
mrl= new MediaLocator(url);
player = Manager.createPlayer(mrl);
player.realize();
// wait for realizing
while (player.getState() != Player.Realized){
     try
Thread.sleep(10);
} catch (InterruptedException e)
e.printStackTrace();
player.start();
with IP is the other party IP specified in the SDP, and the Port is the port specified in the SDP too.
with wireshark, i've seen that RTCP is seen (Receiver Report, Source Description), and RTCP replies are received (Sender Report, Source Description), but RTP data is not received.
i realize that JMF open the same local port as the port specified in the MediaLocator. while actually in my INVITE SDP, i tell the other party a different port. might this be the problem that i don't receive any RTP data?
Thank you.

Answer 1

Hey,
No, the loss of packets isn't something you can control... you lose a packet, you lose a packet. The different encodings could have an affect on the impact of the packet loss, however, but the actual loss of the packet is out of everyone's hands. Even God loses packets as they travel on the wire...Well, I went again to Wiki to look for that page and you are right, I am wrong, it didn't say anything about packet loss, but it was referring to the call distortion and wrongly concluded something about the packets.
Ummmm, maybe. The issue isn't as simple as knowing the public IP address of a client behind a NAT, it's also a matter of traversing the NAT itself. But if the SIP UAS handles all of that, then yes, you should be fine.after putting it to the test, I'm really confused...
I'll try to lay it out so it would make sense and if that wont work I'll post my code here. there is just a lot of it in a few classes.
This is tested with one way streaming!
*1.* I've been trying to transmit audio and video within my home LAN, I've managed to send from one computer to the other, from beginning to end.
This is what I receive on the callee computer in my home LAN:
Participant added to list: ACER-LAPTOP/10.0.0.2
  - A new participant had just joined: TacB0sS@Acer-LapTop
New Stream Event received: StreamMappedEvent
  Stream: com.sun.media.rtp.RecvSSRCInfo@13e6346
  Participant: com.sun.media.rtp.RTPRemoteSourceInfo@1cb374f
  Source: RTPManager
     SSRCCache  com.sun.media.rtp.SSRCCache@cc9d70
     Dataport  33444
     Controlport  33445
     Address  10.0.0.1
     RTPForwarder  com.sun.media.rtp.util.PacketForwarder@17456bc
     RTPDemux  com.sun.media.rtp.RTPDemultiplexer@ea85b4
New Stream Event received: NewReceiveStreamEvent
  Stream: com.sun.media.rtp.RecvSSRCInfo@13e6346
  Participant: com.sun.media.rtp.RTPRemoteSourceInfo@1cb374f
  Source: RTPManager
     SSRCCache  com.sun.media.rtp.SSRCCache@cc9d70
     Dataport  33444
     Controlport  33445
     Address  10.0.0.1
     RTPForwarder  com.sun.media.rtp.util.PacketForwarder@17456bc
     RTPDemux  com.sun.media.rtp.RTPDemultiplexer@ea85b4
new stream arrived fromcom.sun.media.rtp.RTPRemoteSourceInfo@1cb374f
  - Recevied new RTP stream: JPEG/RTP*2.* But when I try to transmit to my friends computer, which is far far away... I do receive NewParticipantEvent, and I do get StreamMappedEvent, but no NewReceivedStreamEvent. sometimes I received an InactiveReceivedStreamEvent but to the caller computer, not to the callee. I thought perhaps the log would help:
This is what I get when I try to call my friends remote computer, on his computer:
Participant added to list: xx.xx.xx.xx.bb.netvision.net.il/xx.xx.xx.xx
  - A new participant had just joined: TacB0sS@dell-laptop
New Stream Event received: StreamMappedEvent
  Stream: com.sun.media.rtp.RecvSSRCInfo@198a455
  Participant: com.sun.media.rtp.RTPRemoteSourceInfo@aa37a6
  Source: RTPManager
SSRCCache  com.sun.media.rtp.SSRCCache@12b7eea
Dataport  33444
Controlport  33445
Address  192.168.2.101
RTPForwarder  com.sun.media.rtp.util.PacketForwarder@99353f
RTPDemux  com.sun.media.rtp.RTPDemultiplexer@76e369
And this is what I get on my computer when I call my friends:
New Stream Event received: InactiveReceiveStreamEvent
  Stream: null
  Participant: com.sun.media.rtp.RTPRemoteSourceInfo@7b7b11
  Source: RTPManager
     SSRCCache  com.sun.media.rtp.SSRCCache@cc9d70
     Dataport  33444
     Controlport  33445
     Address  10.0.0.1
     RTPForwarder  com.sun.media.rtp.util.PacketForwarder@17456bc
     RTPDemux  com.sun.media.rtp.RTPDemultiplexer@ea85b4This is really bigger then me, we've tried to play a bit with configuration, but I just don't see the point, some events are received some are not...
What am I missing?
Thanks,
Adam.
Edited by: Adam-Z. on Jun 14, 2010 7:34 PM