VideoHelp Forum
+ Reply to Thread
Results 1 to 16 of 16
Thread
  1. Hi,

    I'm quite new in this video world, so I don't even know if the following is possible. I hope the question fits to this forum. Any help is appreciated!

    I'm planning to put up the following scientific setup: I'd like to capture video from two screens at resolution 1600x1200 and sync the video with the voice from microphone. The other screen shows my software running and the other screen shows pictures and video from web cam that is recording subject's face. I'd like to capture even small facial expressions, so quite high fps is required (>20).

    I've tried many (sigh...) different screen capture programs, but all of them have some problems. The one that gets most close to what I want is BB FlashBack, but it achieves at most 15 fps and voice sync is a problem. I have relatively powerful computer but the screen capture process takes 50-80 % of the processor time, which is too much.

    So - do you see any solution for this? Is purely software based solution doomed to fail? If video capture card(s) could be used, how would this happen? To me it seems appealing solution to attach some kind of "capture box" between computer and displays.

    Thanks a million!
    Quote Quote  
  2. Originally Posted by jazuju View Post
    I'd like to capture video from two screens at resolution 1600x1200... >20 fps... Is purely software based solution doomed to fail?
    Yes. 3200x1200 is just too many pixels to be moving around.

    Originally Posted by jazuju View Post
    If video capture card(s) could be used, how would this happen? To me it seems appealing solution to attach some kind of "capture box" between computer and displays.
    I don't think you're going to find anything that can capture 1600x1200 at >20 fps. If you can switch to 1920x1080i30 you can use a high def capture device like the BlackMagic Intensity or Hauppauge HD PVR. With the former you will need two devices and two more computers to handle the capturing. I don't know if you can use two Hauppauge HD PVRs in one computer. If you can, there is some possibility you could run the two caps on the same computer that's running your software. The HD PVR will also require dual component video outputs from the computer. I've never seen that on a single video card so you'll probably need to use two video cards. With both of those products you'll have to sync the two caps later.

    You have a webcam that puts out a 1600x1200 image at >20 fps? Or are you capturing at a lower resolution and just displaying at that resolution? If the latter you might be able to save the video directly from the webcam and screen cap your software at 1600x1200.
    Last edited by jagabo; 26th Oct 2010 at 07:14.
    Quote Quote  
  3. Thanks jagabo, this is really valuable information for me!

    OK, I didn't explain the setup very clearly. The first screen has to have resolution 1600x1200, because my software requires that. The other screen could actually have lower resolution, e.g. 640x480, because its main function is to show some simple pictures for the subject. Webcam has resolution 640x480, and the picture window is placed above my program on the first screen or is captured separately in the background (as the BB FlashBack software does).

    I'll try next to lower the resolution of the picture screen and see what happens. If it doesn't work, I'll have to take bigger guns in.. i.e. the capture cards..
    Quote Quote  
  4. So you really only need to record the one 1600x1200 display?
    Quote Quote  
  5. Yes. You made me think about lowering the resolution of the other screen. So the setup would be 1600x1200 + 640x 480 (or 800x600). I haven't had time to check the performance yet, but I'll report the results tomorrow.
    Quote Quote  
  6. Originally Posted by jagabo View Post
    So you really only need to record the one 1600x1200 display?
    I read your question once again and figured out what you really were asking... I have to record two displays, but only the other is 1600x1200.
    Quote Quote  
  7. Have you tried fraps? You'll need some fast compression with 1600x1200. What CPU do you have?
    Quote Quote  
  8. Yeah, I tried FRAPS also, but it can't record desktop applications under XP that I'm forced to use. Processor is Intel Xeon W3530.

    Lowering the resolution of the other display to 640x480 improved performance a bit. I also replaced my old VelociRaptor hard drive with SSD, which may improve something as well.

    After googling around and sending some questions to Blackmagic it seems impossible to capture 1600x1200 video with video capture cards. So I'll stick with the software capturers. I actually have already managed to record the setup 1600x1200 display + 640x480 display + 640x480 webcam + voice at almost satisfying speed.
    Quote Quote  
  9. Originally Posted by jazuju View Post
    Yeah, I tried FRAPS also, but it can't record desktop applications under XP that I'm forced to use. Processor is Intel Xeon W3530.
    I didn't realize fraps wouldn't record desktop apps.



    Originally Posted by jazuju View Post
    After googling around and sending some questions to Blackmagic it seems impossible to capture 1600x1200 video with video capture cards.
    I believe there are some but the BlackMagic cards are limited to standard HDTV resolutions. Which is why I suggested using 1920x1080i30 if you wanted to try the BMI or HD PVR.

    Originally Posted by jazuju View Post
    So I'll stick with the software capturers. I actually have already managed to record the setup 1600x1200 display + 640x480 display + 640x480 webcam + voice at almost satisfying speed.
    VirtualDub has a screen capture module you might try out. You can run two instances of the program but I don't know if you can capture dual displays.

    Another thing to try is capturing each display to a separate drive.
    Quote Quote  
  10. Member
    Join Date
    Jul 2001
    Location
    United States
    Search Comp PM
    Originally Posted by jagabo View Post
    Another thing to try is capturing each display to a separate drive.
    Exactly what I was going to suggest... Just looked up your cpu and that should be more than fine. My only guess is that the capture software may not be multi-cpu optomized. Though if you've got many other apps running at the same time, a quad core may not be enough with two concurrent captures going.
    Have a good one,

    neomaine

    NEW! VideoHelp.com F@H team 166011!
    http://fah-web.stanford.edu/cgi-bin/main.py?qtype=teampage&teamnum=166011

    Folding@Home FAQ and download: http://folding.stanford.edu/
    Quote Quote  
  11. Member
    Join Date
    Jul 2001
    Location
    United States
    Search Comp PM
    Deleted. Sorry, double post...
    Last edited by neomaine; 29th Oct 2010 at 12:45.
    Have a good one,

    neomaine

    NEW! VideoHelp.com F@H team 166011!
    http://fah-web.stanford.edu/cgi-bin/main.py?qtype=teampage&teamnum=166011

    Folding@Home FAQ and download: http://folding.stanford.edu/
    Quote Quote  
  12. Hi guys! Thanks for advice.

    I gave a look for VirtualDub, but it seems to need to put up a "virtual webcam", e.g. "VH Screen Capture Driver", which sounds too much hassle to me. Today I found a program called Camtasia, which seems to be one of the top programs for this purpose. According to first quick tests it seems to be clearly most efficient: capturing two displays at 1600x1200 at 15 fps plus 640x480 webcam at 30 fps, CPU load stays under 30 %. It's also clearly more expensive than the other options. Now I'll try to record 25 fps. I'm quite amazed how big differences there are between screen capture programs!
    Quote Quote  
  13. I assumed you had already tried Camtasia since it's one of the most popular. I suspect the biggest difference you're seeing between the capture programs (aside from the UI) is the compression codecs they're using.
    Quote Quote  
  14. Originally Posted by jagabo View Post
    I assumed you had already tried Camtasia since it's one of the most popular.
    Yeah, I actually tried in the beginning it but didn't figure out the possibility to record multiple screens.

    I tried now recording 2 x 1600x1200 + webcam, all at 30 fps. Processor load was under 50% and voice was in sync. Hooray! It seems that after all it is possible to do such a heavy recording.

    Thank you a lot for your great advice!

    All good!
    -- jazuju
    Quote Quote  
  15. Originally Posted by jazuju View Post
    I tried now recording 2 x 1600x1200 + webcam, all at 30 fps. Processor load was under 50% and voice was in sync. Hooray! It seems that after all it is possible to do such a heavy recording.
    I didn't think that was possible. Good to know!
    Quote Quote  
  16. Member SHS's Avatar
    Join Date
    Oct 2000
    Location
    Vinita, Oklahoma
    Search Comp PM
    It can be done how ever the eazy way cost major $$$$$$ it custm made hardware ans softwre or more cheap way you need setup dual Recoding from each output then Stitch both Video Into Panoramas
    Quote Quote  



Similar Threads

Visit our sponsor! Try DVDFab and backup Blu-rays!