Jin Tian jintian at nlsde.buaa.edu.cn
Sat May 25 11:13:17 CDT 2002

Hi, Ivan and Abraham:

  The WDM driver is based on DirectShow System, which is not design for network program (design for stream program). So, there is much difference between these two. At least I think so.

  Using VFW is not a mistake, as far as I think so. A lots of video capture card support Vfw and WDM both, and only some of them using Vfw-WDM-Mapper. According to our testing, both the mapper and the vfw driver will NOT cause program to be slow. 

  In my computer (Dell Presion 420, PIII 933x2), I use our program to capture 2 streams by 2 Osprey Card at 25fps/H261/Q=5. Totaly CPU usage is mostly 0.000 (test by perfmon), and no more than 1.5 at whole time, if the motion of video is very slightly.

  We can not found Hauppage cards in China. Another card we test is Princle. Its performance is also very well. But I do not suggest you to use this card, because it might stop responsing sometime (though very rarely).

======= At 2002-05-25, You wrote =======

>Hi Abraham,
>It's great news that you are working on installing an Access Grid Node!
>Anything we can do to help we'll try to do.
>I'm not familiar with VCON or the Accord MCU, but I'll do the best that
>I can.
>On question #1: VFW vs WDM, this is what I've learned:
>Vic is using the older vfw api because it's older code, primarily
>supported on non-microsoft operating systems.  Converting it to use the
>more modern WDM, or more current DirectShow interfaces to Video Capture
>would be ideal, but we haven't gotten to it.  From what I do know, the
>vfw API is a legacy interface on most current capture hardware, so as
>such it might have lower performance, but I'd be surprised if it was a
>full 10 FPS! 
>Jay Beavers from MS Research might have some better suggestions.
>On question #2: Which capture card to use:
>We recommend the Hauppage card because we're familiar with it.  We've
>also used the Osprey card (at least one model anyhow).  If you are
>familiar with other capture cards and can debug the interaction with
>Vic, I'd say go for it.  But, you'll get less help from the current
>community than you would if you use what's more familiar.  It's a
>trade-off, but the choice is yours.
>-----Original Message-----
>From: owner-ag-tech at mcs.anl.gov [mailto:owner-ag-tech at mcs.anl.gov] On
>Behalf Of AGAY at vms.HUJI.AC.IL
>Sent: Saturday, May 25, 2002 5:51 AM
>To: ag-tech at accessgrid.org
>Subject: [AG-TECH] VfW and WDM
>                                                  ag-tech at accessgrid.org
> Hi,
> We are trying to build a kind of mini Access Grid node  (actually there
>will be 4 of them, one in each campus).
> We would also like to use the mini node as a conference
> room for VRVS (we have a reflector), and with the VCON
> H.323 clients and Accord MCU already bought by our IUCC.
> Some dumb questions:
> 1.  Both VRVS/VIC and AG/VIC use on Windows the VfW
>     (Video for Windows) driver interface.
>     If the video capture card driver is WDM, then the
>     Microsft VfW-to-WDM Mapper automatically kicks in
>     and provides compatibility?  Is it possible the
>     Mapper will lower frame rate by a factor of 10?
>     Should we use only VfW drivers?
> 2.  Should we stick with Hauppauge or Osprey capture
>     cards, or others like LifeView/FlyVideo are ok?
> Abraham Agay
> ---
> Abraham Agay (Hebrew U. of Jerusalem)
> Email:  agay at vms.huji.ac.il

= = = = = = = = = = = = = = = = = = = =

  Best Wishes to u.

	Jin Tian(金天)
	PhD. Student
	Advance Network Technologies Group (Admire Group)
	National Lab of Software Development Environment
	Beijing University of Aeronautics and Astronautics
	P.B.: 2-83# 37 Xueyuan Road  Beijing 100083  P.R.China
	E.B.: jintian at nlsde.buaa.edu.cn
	P.N.: (86)(10)82317603(O)

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