Re: ProMovie Spectrum

Steve Edgar (se10@cornell.edu)
Mon, 1 Aug 1994 10:49:43 -0400


Actually, it is neither Microsoft nor the video capture hardware vendors who
are at fault. The Video For Windows (VFW) video capture API does provide
device independent video capture, but does not lock down how captured images
may be stored or compressed. This important distinction makes possible
advances in speed/compression/color/image size without affecting the capture
API. This is where specialized processors and CODECs (COmpressor
DECompressor software which is "installable") advance the state of the art.

A program like VFW's VidCap relies on the video capture API and CODECs to
digitize video from a wide variety of capture cards. But the requirements
of sending real time digital video over a network can be considerably
different than "streaming" digitized video to disk. Consequently, CU-SeeMe
does not use CODECs, but does use the VFW capture API.

Not using CODECs means CU-SeeMe has to know exactly how captured images are
stored. Right now, it only knows how to deal with "8 bit palettized"
images; an image format the Intel capture cards do not support, and the Pro
Movie is seems to handle a bit differently than the Creative Labs product.

So, supporting lots of cards means either building in image processing
support for more image formats into CU-SeeMe, or trying to redesign CU-SeeMe
around CODECs.

-- Steve.

At 07:01 AM 7/30/94 -0400, Chris Hand wrote:
>Martin Storer said:
>> I investigated the ProMovie Spectrum Card [...]
>>
>> "The Movie Machine" [...] bottom 10% of the window with the remaining
>> top 90% being grey.
>> [...]
>> "The AVIator" This card does not work with CUSM at the moment.
>
>How come there are so many PC cards that don't work? I had presumed
>that the idea of a standardized API such as Video for Windows would allow
>code written for the API to work with all VFW supported cards.
>
>Is it microsoft's fault? The card manufacturers? Just wondering...
>
>Chris