As many of you may know I have been working on adding XMPP Jingle to the next release. The last two nights ive been up all night trying to get a RTP packet to go from one host to another. Everything looked ok but for some reason VOIP wouldnt work.  I’ve been sniffing my network looking for packets  and kept gettin 100% loss.  Host is sending out but nothing comes in the other end.   I just  noticed what was wrong.    Look at this packet capture log. Notice something odd about the second IP address? It should be

Who ever runs the 45.x.x.x network has probably blacklisted me for blasting UDP packets at them all the time in the wee hours of the night
This i why you should ALWAYS make sure that when two computers talk the bye order is network byte order and not host byte order!

2 thoughts on “Jingles and Tribulations”

  1. Good find on the network order issue.

    I think that you should also take a look at your RTP packet size. For G.711, typical packets should be in the ~200 byte range.

    If you are packing a lot of samples together into each RTP packet payload, then the audio will have a large delay from one user to the other.

    Lastly, PMCA is rarely used in the US. PMCU is the preferred codec.

    Keep up the great work, Monal looks awesome.


    1. I am using PCMA because apparently thats what is used in international communication and even u-law networks switch to a-law when talking to a host that is a-law. Though since I am not quite interfacing with telephone networks yet, its not really an issue.

      I’ve since reduced my packet size to 214 bytes, 54b header and 160b payload. Still havent sorted out a slight output jitter yet. That’s the last major hurdle.


Comments are closed.