[AG-TECH] Quad Capture card performance

[Natalia Costas Lago]

Hi everybody,

Does anyone the advantages of the Spectra8/Winnov Videum 4400 over the 
Hauppauge Impact  VCB?

The hauppauge card is almost 5 times cheaper than the others. Maybe there is 
something am I missing?

Thanks in advance for ur help.

Kind regards,
Natalia.

----- Original Message ----- 
From: "Natalia Costas Lago" <natalia at cesga.es>
To: "Derek Piper" <dcpiper at indiana.edu>
Cc: "ag-tech" <ag-tech at mcs.anl.gov>
Sent: Monday, April 25, 2005 4:05 PM
Subject: Re: [AG-TECH] Quad Capture card performance


>
> Thanx a lot Derek!!
>
> That was enlightening!!
>
> ----- Original Message ----- 
> From: "Derek Piper" <dcpiper at indiana.edu>
> To: "John Hodrien" <johnh at comp.leeds.ac.uk>
> Cc: "ag-tech" <ag-tech at mcs.anl.gov>; "Natalia Costas Lago" 
> <natalia at cesga.es>
> Sent: Monday, April 25, 2005 3:29 PM
> Subject: Re: [AG-TECH] Quad Capture card performance
>
>
>>
>> Of course if the system you're installing on only supports 32-bit x 33Mhz 
>> slots (as many do) then you're not going to get a lot of benefit. 
>> Natalia, what are the hardware specs on the capture machine you're 
>> upgrading or rebuilding?
>> It's important to note too that however many PCI *slots* you have, you 
>> (normally) only have one PCI *bus*. And the TOTAL bandwidth of that bus 
>> is 32bit x 33Mhz = 132MBytes/sec. So however the cards are arranged 
>> (singly or quad) you're going to run into that same bandwidth limitation. 
>> Of course the quad capture card might be slightly more efficient due to 
>> it being the only card on the bus and thus eliminating bus contention 
>> between the capture cards.
>> To reiterate the math here?
>>
>> 33000000 x 32 = 1056000000 bits/sec PCI max
>>
>> = 132000000 bytes/sec PCI max
>>
>> 1 frame (24 bit color) = (768 x 576 x 24 / 8 ) = 1327104 bytes
>>
>> 25 fps = 33177600 bytes/sec
>>
>> x 2 captures = 66355200 bytes/sec
>>
>> x 3 captures = 99532800 bytes/sec
>>
>> x 4 captures = 132710400 bytes/sec
>>
>> Derek
>>
>> John Hodrien wrote:
>>> On Mon, 25 Apr 2005, Natalia Costas Lago wrote:
>>>
>>>>
>>>> We are about to purchase a Spectra8 capture card or Winnov Videum 4400. 
>>>> It's
>>>> a very good point not to have to use 4 PCI buses, that's what I like 
>>>> most of
>>>> both cards, however I am concerned to performance issues, I mean, a PCI 
>>>> bus
>>>> allows 132 Mbps more or less, and the Spectra8 delivers 4 videostreams 
>>>> at
>>>> 30fps 768x576 (it can be less, that's the worst case) (similar values 
>>>> for
>>>> the Videum 4400 card). So, it seems to me that the PCI bus cannot 
>>>> transmit
>>>> so much information, that means, does it drop frames? Maybe I cant get 
>>>> the
>>>> highest resolution at 30fps (25fps for the Winnov card)?.
>>>
>>>
>>> It won't be 30fps at 768x576 will it?  That's PAL resolution at NTSC 
>>> frame
>>> rates.  If you drop that to 25fps, the back of my envelope looks like 
>>> you'd
>>> indeed be rather close to 32 bit PCI limits.  The 4400 supports 64bit 
>>> PCI,
>>> thus solving that problem.
>>>
>>> jh
>>>
>>
>> -- 
>> Derek Piper - dcpiper at indiana.edu - (812) 856 0111
>> IRI 323, School of Informatics
>> Indiana University, Bloomington, Indiana
>>
>
>