Re: XForms: How to display real time images

Steve Lamont (spl@szechuan.ucsd.edu)
Thu, 21 May 98 05:56:47 PDT

# To subscribers of the xforms list from spl@szechuan.ucsd.edu (Steve Lamont) :

> ... Is
> it possible to have real time image display (with frame rate >12fps) with
> image compression/decompression overhead on the server and client
> programs? Would you suggest some tools for us to achieve the task? Would
> you explain how to display an image on a Canvas?

The Canvas is just a wrapper around a plain old X Window into which
you can draw however you wish.

Basically, I'd use the XShm extension where ever possible. Create a
shared memory Pixmap and stuff the image data into it. You may need
two for double buffering if you need.

It's probably easier for you to fetch up the MIT-SHM than for me to
try to explain the nitty gritty details. There's probably a file
called mit-shm.PS.Z lurking in your X distribution somewhere -- most
likely in xc/doc/hardcopy/Xext. If you can't find it there, check
your favorite X repository on the net. If that fails, let me know and
I'll make arrangements to either mail you a copy or provide it via
anonymous FTP.

What kind of machine are you planning to use to display your video?
What kind of graphics card?

spl
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