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Started by Jon Crowcroft
Thu, 08 Oct 1998 00:00
Re: [mbone-be] Re: MBone services
Author: Jon Crowcroft
Date: Thu, 08 Oct 1998 00:00
Date: Thu, 08 Oct 1998 00:00
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In message <199810081438.QAA24919@vivaldi.belnet.be>, Patrick De Muynck typed: >>I've seen the quality that a PictureTel H.320 terminal at 3xISDN can >>achieve (that is 384 Kbit/s for video *and* audio). >>Then coding the same content with vic on a Digital-alpha Workstation >>(500MHz) was a very disappointing experience. Even at 600 Kbit/s you >>cannot obtain the same quality. thats not com>>paring like with like try a PC with an H263+ codec over 384kbps worth of IP actually , yo umust be using an old Vic too - motion JPEG or MPEG or other codecs in Vic can do very well albeity at higher bandwidth, but thats nothing to do with multicast >>I think that the absence of motion estimation in vic's H.261 >>implementation is probably most responsible for this, but I don't >>really have the expertise to make a final judgment on this matter. >>I understood that the motivation of vic's authors not to include >>motion estimation was to make the codec more robust in the face of >>packet losses. I wondered if this is the case in the H.261 >>implementations of the new H.323 conferencing products (which will be >>susceptible to the same packet losses) ?? sure - there are experimental h.263+s in vic too they arent bad - the mbone tools (public domaon) are catching up again, but this is orthogonal to network serice >>I think that the way to go for both commercial and non-commercial >>software is to use "hardware" H.261 compression (or whatever standard) >>on the video-capture board. I also guess that then I wouldn't be >>so annoyed with the delay that the video has with respect to the >>audio (very annoying on my SGI-O2, or am I doing something wrong?). well the SGI O2 isnt really a lightning machine.....note there are better audio systems around as well as video - but i was responding to critique of the network, not of the toolsets... cheers jon
Re: [mbone-be] Re: MBone services
Author: Chris Rapier
Date: Thu, 08 Oct 1998 00:00
Date: Thu, 08 Oct 1998 00:00
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> but i was responding to critique of the network, not of the > toolsets... Ahhh, that might be the problem then. I think the MBONE is perfectly fine and very useful as a network. I should have said that I do not think the golden application, the one that will get the average network consumer (say Bob in NYC who just signed up with Netcom) to stand up and say, hey! Multicast rocks!, exists. However, the fact that Real Video 5.0 has multicast support changes much of this. The goal now would be to get content providers to distribute more than IETF meetings and technical conferences. NB: I know that there are several mbone based radio station feeds and probably a non tech video feed or two. However, more are needed if MBONE and MBONE technology are going to gain the lead (eg. overtake traditional ip network models for distributing media feeds). I think a business case FAQ is an excellent idea.
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