Hi All,
Wesley Hosking wrote:
> One of the gentlemen using a Dipix card used rt-linux to get some
> extra functionality out of the driver. (It has an on-board TI C44 DSP
> with a DMA transfer that had some problems, that haven't been fixed in
> the driver... ). I believe his objective was to sync the frame
> acquisition and display.....
Part of what I was trying to do with RTLinux and the Dipix FPG-44 was to
minimize the lag from when a frame became available to when I could
actually operate on the frame. I was also interested in maintaining a
30 FPS video stream under high load. RTLinux definitely helped with
this.
The problem was with synchronizing RTLinux to the framegrabber because I
have to poll to determine if a frame is available. Interrupts are only
generated on DMA completion. There was sufficient evidence in the Dipix
documentation that PIO was just as fast, if not faster, than DMA so I
didn't explore adding DMA to the driver. Right now, I estimate the
synchronization by measuring the interval between frames becoming
available and using that as the period to a RTLinux task. Currently,
I'm stuffing the frames into a shared memory buffer, but I had
investigated using a RTL task to not only grab the frames but to display
them in X using the DGA extension.
> I haven't heard of anyone doing it with a Matrox grabber, but the
> techniques would be similar IMHO.
Yes, the techniques would be similar. The way I handeled it with the
Dipix driver was to cut-and-paste the necessary parts into a RTLinux
task. If anybody wants to discuss this further or would like to see
some code, feel free to contact me.
Rick
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Richard J. Wood -- [EMAIL PROTECTED] -- http://cns-web.bu.edu/~rjwood
Computer Vision/Computational Neuroscience Laboratory
Department of Cognitive and Neural Systems
Boston University
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