> -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED]] On Behalf Of Greg Breland > Sent: 21 December 2001 23:36 > To: [EMAIL PROTECTED] > Subject: RE: Serve Side scaling > > > Actually, you would not see much of a drop in bandwidth > unless the page was heavy on graphics. By scaling the the > screen you are compressing it and therefore, making it more > random. This will cause hextile to be less effecient and > therefore erase your gains. You might even slow things down > with the tight encoding since almost eveything will have to > be jpeg encoded. >
Incorrect. For a "typical" environment (i.e. remote-controlling a PC), the complexity of the screen doesn't change much, and the bandwidth required drops significantly. Specifially - 1) For regions with complex imaging, less data is transmitted (e.g. 1 hextile instead of 4 for 1:2 scaling) so again there is a big performance boost. [Each hextile containing a 32x32 bitmap in either case]. 2) On regions with patterns (e.g. text), the number of pixels that differ from the background is actually reduced, again improving performance. (As hextile uses a fixed 32x32 pixel region, the number of tiles you transmit is reduced dramatically, more than compensating for the increase in pixels-per-hextile). 3) Similarly to 1), for solid-colour regions, less data is transmitted (e.g. 1 hextile instead of 4 for 1:2 scaling) [Each hextile containing just the background colour in either case]. The point is that the scaling of the screen actually has a minimal effect on the "randomness" of the data, and the advantages of the lower amount of hextiles/screen data are a major bonus. As an example, a standard Windows desktop (i.e. with taskbar at the bottom, some icons down the left hand side, couple of medium-size app windows open) will download in approx. 5-8 seconds over a 9600bps serial link with PPP, compressed to 160x120 pixels (original size 800x600), whereas the full-size desktop would take at least 40-60 seconds. On top of this, PalmVNC only grabs the region of the framebuffer that it needs to display, rather than the entire display (scaled or otherwise), which gives a massive performance improvement over almost any other VNC client (unless they've been changed to do this in the last 6 months). Basically, it should never take more than 15 seconds @ 9600bps to grab an entire Palm screen from the server, regardless of scaling, complexity etc. Try doing that with a standard client (e.g. PocketPC) when the server is 1600x1200 with complex bitmaps and apps running. Chris. --------------------------------------------------------------------- To unsubscribe, mail [EMAIL PROTECTED] with the line: 'unsubscribe vnc-list' in the message BODY See also: http://www.uk.research.att.com/vnc/intouch.html ---------------------------------------------------------------------
