BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Re: Need to improve a remote control software...          BorlandTalk.com Forum Index -> Delphi Internet Winsock View previous topic :: View next topic   Author Message Sven Ratzlaff Guest Posted: Wed Sep 07, 2005 7:16 pm    Post subject: Re: Need to improve a remote control software... Hello, Quote: To transfer the desktop image... we capture the screen to a BMP, then save it to JPG, compress it using UCL compression and save to a Stream, just to send it to the remote computer. Just an idea: Since JPG is an image compression format you do a "double compression". Skip JPG and compress your BMP with UCL comression directly... Sven Back to top Remy Lebeau (TeamB) Guest Posted: Wed Sep 07, 2005 8:07 pm    Post subject: Re: Need to improve a remote control software... "Santy Concepción" <santyweb (AT) hotmail (DOT) com> wrote Quote: To transfer the desktop image... we capture the screen to a BMP, then save it to JPG, compress it using UCL compression and save to a Stream, just to send it to the remote computer. Is this the faster method? JPG is already compressed quite a bit, so using additional compression won't help much. I would suggest using either JPG or UCL but not both. Also, since JPG is a lossy format anyway, it would probably be better to just compress the BMP directly instead of using JPG (unless you don't care about reproducing the original quality of the images on the receiving end). Also, the best way to send a series of images quickly is to not send complete images to begin with. After you have sent the first image, each subsequent image should only send the *differences* from the previous image for the portions that have actually changed. This means that you are transmitting much less data, and performing less intense image updates on the receiving end. Of course, you should send a complete image periodically, say once a minute or so, to ensure that the display on the receiving end stays in sync and can recover if the image differentials beome out-of-sync or corrupted. Gambit Back to top Jim P Guest Posted: Wed Sep 07, 2005 8:33 pm    Post subject: Re: Need to improve a remote control software... Remy Lebeau (TeamB) wrote: Quote: "Santy Concepción" <santyweb (AT) hotmail (DOT) com> wrote in message news:431f36fa$1 (AT) newsgroups (DOT) borland.com... To transfer the desktop image... we capture the screen to a BMP, then save it to JPG, compress it using UCL compression and save to a Stream, just to send it to the remote computer. Is this the faster method? JPG is already compressed quite a bit, so using additional compression won't help much. I would suggest using either JPG or UCL but not both. Also, since JPG is a lossy format anyway, it would probably be better to just compress the BMP directly instead of using JPG (unless you don't care about reproducing the original quality of the images on the receiving end). Also, the best way to send a series of images quickly is to not send complete images to begin with. After you have sent the first image, each subsequent image should only send the *differences* from the previous image for the portions that have actually changed. This means that you are transmitting much less data, and performing less intense image updates on the receiving end. Of course, you should send a complete image periodically, say once a minute or so, to ensure that the display on the receiving end stays in sync and can recover if the image differentials beome out-of-sync or corrupted. Gambit Good comments. JPG can take a bit of time to generate. So I would suggest staying away from JPG. and are not that good for text - mainly for pictures. I have done JPG on black and white and text and found that Tif was smaller. Jim P. Back to top Ciaran Costelloe Guest Posted: Wed Sep 07, 2005 11:41 pm    Post subject: Re: Need to improve a remote control software... Santy Concepcisn wrote: Quote: Hi! We have developed a remote control application, and it works "fine", so we can see the remote desktop on our screen, move the cursor, click, write, etc... The "problem" is that, we need it to go FASTER! I know it depends on which components we use, network speed and the source code used, but... Which are the best methods to transfer images and info between computers? UDP or TCP? (we use Indy idTCP components) You need to send differences (see below) so UDP is out. UDP would mean your code would have to deal with missing parts of an image or diff, making your code more complex and slower. Quote: To transfer the desktop image... we capture the screen to a BMP, then save it to JPG, compress it using UCL compression and save to a Stream, just to send it to the remote computer. Is this the faster method? Forget about image formats. Send the screen size and colour-bit depth once, then send one full screen capture (don't waste your time converting it to a BMP). Grab another screen capture, and by comparing with the previous capture, transmit the differences only. Use lossless compression (Indy has compression code, but there are also public-domain / open-source compression routines freely available). You cannot use JPG with this methodology: even a slight image change will give significantly different images because of the way JPG compression works, and the number of different bytes would frequently be much higher (on a simplified basis, JPG smudges adjacent colours - changing one pixel from red to blue affects the adjacent pixels also). JPG is also just ugly, particularly in this case: the lines at window borders and at the mouse cursor will not be sharp, and will eventually give the user a pain in the head. JPG is OK for photos but very poor with lines. 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