|PPNCG Information Pages : Video-conferencing : Desktop videoconferencing recommendations (PPNCG) : Notes to the 2nd Edition PPNCG recommendations|
|H.323 solutions fall into
two main categories: those based on hardware codecs, and those based
on software codecs.
In our community, the only widely-tried H.323-based software-codec solution had been MS NetMeeting, used with an inexpensive PC-camera and with either a headset or the SoundPoint/PC echo canceller. There's no disagreement that this is a usable technique when used for personal videoconferencing between consenting participants; the arguments have been about its use in group-sized "business class" multipoint H.323 conferences.
In the past, Netmeeting definitely *has* caused disruption of otherwise satisfactory multipoint conferences due to major audio defects (echoes, noises, and a kind of "motorboating"), and there have also been claims that the use of Netmeeting is implicated in crashing H.323 MCUs.
More recently, OpenH323-based packages such as GnomeMeeting have become available. Again, for point to point use if the participants can make them work then fine, but for multipoint meetings the caveats apply.
The use of software-based codecs such as Netmeeting isn't allowed on the ESnet MCU, nor in H.323 Megaconferences.
There seems little doubt that the use of hardware-codec based H.323 solutions
is very much to be recommended, whatever one's feelings might be
on the possibility of a fallback onto software-based solutions when no other
facility was to hand. Be aware however that H.323 hardware codecs
(Zydacron, ViaVideo etc) are dedicated devices; they are not in general
suitable for arbitrary video capture purposes, such as use with the 'vic' application, webcam, etc.
|Already at the PPNCG's meeting in early 2002, the recommendation for
the Zydacron was "frozen". The product still works, no less than it ever
did, and one of ours is actually QA-tested and accredited to the JANET
videoconferencing service, but at the lower edge of what they would
consider adequate for participation in their service.
Those who already have Zydacron units may of course continue to use them, but look out for notes on incompatibilities and work-arounds in some situations.
The recommndations for 'business-class' H.323 conferencing were:
* (PPNCG RECOMMENDATION NOW FROZEN:) For an extensible group system, the PPNCG had recommended the Zydacron OnWAN solution, based on the Z353 PCI card (a development from the Z350 card, functionally equivalent as far as we are concerned).
* For a relatively portable personal system, that can be swapped around between desktop machines and laptops as required: the Polycom/Polyspan ViaVideo (USB-connected). This is less than half the cost of the Zydacron card, but what you get is essentially all that you get: there are no options for upgrading video inputs etc.
Updating this article as of Oct 2003, one can say that the ViaVideo units have been a success story, for the personal workstation situation. However, they don't take an external video input.
The then-current VCON ViGo product had been assessed at the time, and rated as poorer value than the ViaVideo; however, it appears that there's a new model of the product out now (2003) in the Americas, and some good reports have been heard. It costs, it seems, roughly 50% more than the ViaVideo, but it does accept external video input. The product has a number of other attractive features. Since the offering hasn't been directly assessed by, or on behalf of, the PPNCG, we can't make any specific recommendations here, but it seems worth considering, at least when the new model is available in Europe. http://www.vcon.com/solutions/videoconferencing/desktop/ViGO/index.shtml
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