Forgive me for my ignorance, but I was under the impression that the unix versions did nothing whatsoever with the video card? Isn't that why I can be logged on to my home server from work, yet my wife doesn't see anything different on the server screen itself?
Ben ----- Original Message ----- From: "Jonathan Morton" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Cc: "Jerry McBride" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]> Sent: Tuesday, April 01, 2003 7:30 PM Subject: Re: VNC & AVI files > >>> Easy answer. The RFB protocol picjs up the video information before > >>> it > >>> gets to the videocard. this menas that the Video overlay is not > >>> picked > >>> up as this is done at the card. For vidoe not using overlay, VNc > >>> refresh > >>> rates are just to slow to mantain a stream( this is the reason Quake > >>> sux > >>> in a remote client) > >> > >> I dunno about that. On my home lan I'm able to view .avi,etc with > >> pretty darn > >> good results. I just wish there was an easy way to get sound from the > >> server to > >> the client as well as the video portion... > > I should probably clarify. VNC picks up screen data from the video > card's framebuffer - so it does NOT pick it up "before" the video card. > The reason why video doesn't show on some systems, is because such > video is being played into a separate buffer, which is then "mixed in" > by the video card's RAMDAC - this is often known as "overlay mode". > > Overlay mode is very common on modern PC-based video cards. It is > almost universal for TV applications (since the Macintosh Quadra AV > series, and early "feature connector" equipped SVGA cards), and > probably DVD as well (if only for "copyright protection" *cough*). It > is also used, to a lesser extent, for certain "ordinary" video codecs, > but normally only the more modern ones such as MPEG and Sorenson, > rather than Indeo and Cinepak. > > VNC is incapable of reading the overlay buffer. If overlay is in use, > you will see a black, blue or purple hole (depending on your particular > overlay implementation) where the video should be. > > VNC *may* be capable of playing video at an "acceptable" rate, if and > only if the following conditions hold: > > - You have a fast, low-latency network - such as switched 100base-TX. > > - Your video card has a high-efficiency "read pixels from framebuffer" > implementation. This is surprisingly uncommon - ATI only implemented > this in one of their most recent Catalyst drivers. Keep up to date > with your video and m/board drivers. Matrox and recently ATI probably > have the best solutions in this particular field. > > - Your server and client have fast enough CPUs to encode and decode > each frame *very* quickly, in addition to the server decompressing the > video. > > - Your server is not using overlay mode to display the original video. > > -------------------------------------------------------------- > from: Jonathan "Chromatix" Morton > mail: [EMAIL PROTECTED] > website: http://www.chromatix.uklinux.net/ > tagline: The key to knowledge is not to rely on people to teach you it. > _______________________________________________ > VNC-List mailing list > [EMAIL PROTECTED] > http://www.realvnc.com/mailman/listinfo/vnc-list _______________________________________________ VNC-List mailing list [EMAIL PROTECTED] http://www.realvnc.com/mailman/listinfo/vnc-list
