archiv~1: Re: SETI Linux signal analysis-video performance of scroll

Re: SETI Linux signal analysis-video performance of scroll

MarcusJohn@aol.com
Thu, 26 Nov 1998 10:39:15 EST

In a message dated 11/26/98 2:55:29 AM Eastern Standard Time,
david@djwhome.demon.co.uk writes:

> Scrolling is very expensive. I seem to remember that specgram writes
> left to right and wraps round, rather than scrolling. (Text mode
> scrolling can use tricks to do with the way the hardware works, which
> are not available to anything using windows (text or graphic)).

Scrolling is very cheap with hardware accelleration available on the video
card. A bit blit to move it up should consume a few cycles, then be done on
the card itself. You should be able to view a whole day in about a second, on
an accellerated card. Not that you could process it between your ears that
fast.
On a windows machine, or on an video accelerated linux machine, the
scrolling should not consume a lot of resources. In any case it will be easy
to benchmark. Just save a whole day of waterfall, and then play it on the
screen as fast as the hardware will show it, with all the other functions
turned off (If the software will allow it). Anything less than a couple of
minutes should have negligible effect on the performance of the seti system.

John Marcus.
KE3SW.