Ambicious project

[sogtulakk]

Why pay $300 for a license on a software we can make ?!
Here is the idea... I´ve seen some great softs to remotelly control a win2000 server, showing the desktop etc.. How can we build our own ??? eg NetOP, etc..
I managed to send screenshots but its slow even over a LAN, I think the best way is to send movment vectors ....

Anybody ???????

Thank you,
Martin Descalzi

[VirtuallyVB]

Every once in a while I think of the performance problems I've had in doing screen capture on a remote machine using Java. Just this moment I thought of using delta frames (change in the frame data) like MPEGs or AVIs (I forget which).

I'd suppose that the remote machine would grab a screenshot and compare it to the last shot and only send the changes. I've never implemented the algorithm myself though, but that is how I would proceed.

I had thought of grabbing the screen shot then sending keyboard and mouse input, but it still wouldn't really sync with causing updates

The game Descent has a cool "record" feature, but I've never deciphered their replay scheme. I don't know if they save inputs and apply them to the engine or if they have saved the video etc. If it's video, the compression is phenomenal.

***EDIT***
Then again, NetMeeting is free. I used to control my pc at work from home with NetMeeting.

Are you looking for the satisfaction of making it yourself or do you need to get a job done now?
***EDIT***

[sogtulakk]

Actually it´s more curiosity and satisfaction than a job.

Maybe comparing 4x4 pixels or 8x8 and sending that block of pixels if they are different.

In the game maybe its DivX, it´s compression is great...

Mmmm.. I never thought about NetMeeting...but my server is not on the internet...how do I see each other...?

[VirtuallyVB]

"Actually it´s more curiosity and satisfaction than a job."
I have the same curiosity and I've been wanting to do video/audio chat as well.

"Maybe comparing 4x4 pixels or 8x8 and sending that block of pixels if they are different."
I was thinking of the entire screen and some boolean operators that will make the non-changed pixels black. Then compress this 'delta' frame and send through the network.

"In the game maybe its DivX, it´s compression is great...
I really have no clue how they do it. Tell me more about this DivX thing. I'm trying to get the compress/uncompress to work.

"Mmmm.. I never thought about NetMeeting...but my server is not on the internet...how do I see each other...?"
It doesn't have to be the internet network. But it was IP, I suppose LAN and Internet at a minimum. At work we'd have LAN meetings and even intercontinental internet meetings. Even though the directory server isn't the way it used to be, if you know the IP for your "NetMeeting Server", you can connect. there are many ways to get your IP address, but from NetMeeting, you can get it from "Help | About Windows NetMeeting" and it's in the bottom left corner (in 3.x versions I suppose). You setup the machine to be a "Server" under "Tools | Remote Desktop Sharing". An icon should appear in the system tray and then a remote machine can call this machine using the IP address.

I'm getting a little upset trying to use Java for the compression. There seems to be a bug, but the class usage definitely isn't documented well.

How are you doing the screen capture? I remember that I was using system resources too much (but I don't remember if it was the screen capture or another part of the code). It probably was sending the screen data uncompressed causing the cpu to peg. What language are you using?

***EDIT***
NetMeeting really is impressive. It is updating the screen at least once per second (I think even faster) and the cpu usage is below 20% even 10%. I found my beginner error in making an intensive loop as a delay and got the cpu usage from 100% down to 40% to 50%, but that doesn't compare to MS's 10-20%. Hopefully when I don't draw the captured screen onto the same pc, it will drop to 20 or 30%. At least I corrected the programming technique to relieve that 100% cpu usage. But that still doesn't take into account processing to decide what to send as an update.
***EDIT***

[Lasse]

Before you start the project, have a look at the VNC software from AT&T. Its distributed under GNU Public License and works fine for remote control (screen, mouse, keyboard) over IP.

[CADMANdo]

Great bit of software and its free. Use it at work as part of support. Can take control of any PC in the business. We use IDSN, works fine using dial-up connections.