Qt doubts

[Richard Moore]

Mathias Puetz wrote:
> 
> On Mon, 31 Jan 2000, you wrote:
> >Hello everybody
> >
> >       I'm doing some research on image processing: I'm acquiring frames from
> >the video-cassete through a frame grabber for post_processing.
> >
> >       The fist thing I'd like to do is to watch TV on my computer. I created
> >a window using the KDevelop wizard and I'm showing successive images
> >using the Qt function btblt(view,0,0,&image). Well, it works but it's a
> >bit slow. How could I improve the performance ?
> >
> >       By the way, I developed a device driver for the Data Translation DT3153
> >frame grabber: it's not full-featured yeat but it's functional. Where
> >could I publish it for the people who want to use it and perhaps help to
> >develop it ?
> Hi,
> 
> You may want to contact the video4linux people. Try
> 
> http://roadrunner.swansea.uk.linux.org/v4l.shtml
> 
> as a starter. These guys should know how to get fast
> access to window buffers in X. Standard X Servers
> (as of release XFRee86 3.3.6) don't allow direct
> hardware access as far as I know, so with current
> X it will never be as fast as M$-Win.
> However there is hope, in the future XFree86 4.0
> will support direct streaming support to write
> directly into video ram (www.precisioninsight.com).
> You may want to join the XFree86 developer mailing
> list to find out more about this.

These are definitely the people to talk to. Direct hardware
access to the frame buffer is already done I think.  Alan Cox
is doing a lot of work on video4linux, so you might also want
to ask him. There is already a KwinTV app on ftp.kde.org that
uses the video4linux API to display tv pictures from TV cards
like the Haupage WinTV cards.

Rich.

> 
> Qt bitblt should give you about the same
> performance as standard XLib bitblt functions.
> (If not send a bug report to Troll Tech)
> It might also be an issue whether your image and
> screen have the same color depth and whether your
> XFree86 server accelerates the bitblt function
> (and possibly depth conversion).
> So it could be an issue of your graphic-card/XFree86
> combo alltogether. Unless you have a Matrox card
> which are very well accelerated under XFree86,
> you may download a trial version of the Accelerated X
> (www.xig.com) to see if this does any better (usually
> it does).
> 
> Hope my hints were helpful,
> Mathias
> 
>  ______________
> /              \
> | Mathias Puetz \__________________________________
> |                                                  \
> | Advanced Materials Lab (University of New Mexico) \
> | 1001 University SE, Albuquerque, NM 87106         |
> |                         \|/                       |
> | phone: (505)272-7132    -O-    fax: (505)272-7336 |
> |                         /|\                       |
> |   \|/    email:       mpuetz at unm.edu       \|/    |
> \___/o\________or puetz at mpip-mainz.mpg.de____/o\____/

-- 
     Richard Moore		rich at ipso-facto.freeserve.co.uk
http://www.robocast.com/	richard at robocast.com
http://developer.kde.org/	rich at kde.org