Alessandro
There is no intention or code that fragments the setup message. It perhaps is the underlying network but that may not be the issue.
I suggest turning off FastStart and H245inSetup. Almost all video conferencing equipment don't use it and some older equipment do not handle the setup message with Fast Connect elements. Ie NetMeeting etc. Try setting in your endpoint initialization
DisableFastStart(true); DisableH245inSetup(true);
That should resolve most interop issues.
Simon
-----Original Message----- From: h323plus-bounces@lists.packetizer.com [mailto:h323plus-bounces@lists.packetizer.com] On Behalf Of Alessandro Angeli Sent: Saturday, November 06, 2010 9:21 AM To: h323plus@lists.packetizer.com Subject: [h323plus] H.225.0 packetization
I've been testing SimplePlus and Ekiga on a C2C connection to a Polycom h/w device over the LAN.
I've run into the following 2 issues with both of the applications:
1. the device only shows a broken static video frame every once in a while
2. the device closes the signalling channel right after receiving the first message
Both issues seem to be have the same underlying cause: the messages and samples are not packetized according to the ITU H.225.0 standard.
More specifically, my understanding of H.225.0:2006 section 6.1 and appendix IV seem to require all messages to fit in a non-fragmented datagram.
However, when I add 1 video codec (H.261) and 6 audio codecs (G.722, G.722.2, GSM06.10, GSM-AMR, Speex), the first message (which contains the codec list) grows beyond 2 KiB and ends up fragmented and rejected by the h/w device.
Also, the video keyframes produce media samples larger than the network's MTU and end up fragmented and the fragments are no longer macroblock-aligned and are dropped by the receiving h/w device (as showed by the device's real-time log). Every once in a while, the beginning of a keyframe is fragmented on a macroblock boundary and the device accepts that part of a frame, which is displayed partly broken (the picture is incomplete) and stays there until the next accidental valid paclet (if ever).
I am in no way an expert on H.323, so my understanding of what is going on may be incorrect. If so, what can I do to correct this observed behavior?
-- Alessandro