VGA to USB (VGA2USB) and DVI to USB (DVI2USB) RGB frame grabbers

Frequently Asked Questions.

• Will VGA2USB or DVI2USB devices work with USB 1.0 or USB 1.1?
  • VGA2USB and DVI2USB will not work with USB 1.x buses as they won't provide enough bandwidth for this device to function.
  • VGA2USB LR, HR and Pro will work with either USB 1.1 and USB 2.0. Although please note that significant performance degradation will occur as data transfer rate of USB 1.x bus is much slower that USB 2.0 bus.
• What the frame rate (number of frames per second) that VGA2USB and DVI2USB devices are capable of capturing? 
  • Detailed technical specification of VGA2USB and DVI2USB devices lists the frame rates of each.
  • VGA2USB will capture between 2 and 28 frames per second, depending on your operating system, screen resolution, refresh rate, how fast changes are happening on the screen,  and speed of your computer hardware. Also if capturing is set to uncompressed frame transfer - there will be more data to send and capture rate might be reduced as well.
  • VGA2USB LR, HR and Pro will capture between 10 and 60 frames per second.
  • DVI2USB will capture between 6.7 and 29 fps.
  • DVI2USB Duo will be released in January 2008 together with final specs. According to manufacturer (Epiphan Systems) it will be the world's fastest dual link DVI Capture device.
• Does VGA2USB or DVI2USB models reduce the image resolution during the capture?
  • No, all VGA2USB and DVI2USB devices capture and transfer every pixel of original VGA image. VGA2USB captures images in 16bits per pixel RGB format. VGA2USB LR, HR and Pro uses lossless compression to capture and transfer original quality imagery. DVI2USB captures images in 24 bits per pixel, 8:8:8 format.
  • All VGA2USB and DVI2USB devices offer better image capture quality than any VGA to video converters paired with Composite or S-Video connector.
• Does VGA2USB or DVI2USB devices support older version of Windows Operating System?
  • VGA2USB (all models) and DVI2USB (all models) does not support Windows NT and lower/older operating systems due to their inferior USB bus support capabilities.
• Does VGA2USB or DVI2USB support capturing to Linux ?
  • For VGA2USB, LR, HR and Pro as well as DVI2USB - we offer Linux SDK, API for the driver and examples. The driver is provided for 2.6.x series of Linux kernel for i386 and x86_64 platforms. Source code for the device driver itself is not provided.
  • VGA2USB LR, HR, Pro and DVI2USB driver supports Epiphan systems proprietary API as per SDK, as well as Video4Linux API.
  • Please contact us if you need device driver for specific version or flavor of Linux you are using.
• Can VGA2USB or DVI2USB device can capture VGA or DVI signals as a movie?
  • Yes, all of the above devices support signal capturing in AVI movie format.
• Which AVI codecs you recommend to use with VGA2USB and DVI2USB devices?
  • For best compromise between image quality, CPU power and compression (final size of saved movie) we suggest using Indeo 5.1 codec with 50% quality setting. Although we recommend you try other settings to find the best combo for your specific needs and set of resolutions, computer hardware and other parameters.
• Images grabbed seems to be shifted to the left or right side. Can this be fixed?
  • VGA2USB and DVI2USB devices implements an algorithm to adjust and crop visible image from VGA frame. Although in some situations it is not possible to automatically adjust the final capture shift perfectly. Please use these steps to perform simple manual adjustments:
    
• Can two or more VGA2USB or DVI2USB devices can be used to capture VGA signals simultaneously?
  • Yes. Epiphan Systems suggests that separate VGA2USB (or DVI2USB) application needs to be ran for each VGA2USB device attached. You will, however, notice a significant difference in frame rate for each additional active VGA2USB. The higher the performance of your computer, the better the possible frame rate. Our internal testing on a Dell Dimension 2400 (Celeron 2.4GHz processor, 512mb RAM) at 1024×768 with two VGA2USB (or DVI2USB) devices yielded average frame rates of 7.1 fps and 4 fps. In contrast, a Pentium 4, 3.0Ghz desktop with 512MB of RAM at 1024 x 768 yielded average frame rates of 9.52 fps and 5.85 fps. Please note that you must start the VGA2USB application after connecting each VGA2USB.
• Can DVI2USB device capture DVI and VGA video signals at the same time?
  • No.
• What kind of protocol is being used by VGA2USB or DVI2USB devices when sending stream of images?
  • The VGA2USB and DVI2USB frame grabbers work by emulating a high resolution video camera for Windows. VGA2USB and DVI2USB are DirectShow compatible device, which makes them compatible with virtually any video capture software designed for Windows. For example, VirtualDUB can be used to record .avi files, Microsoft Media Encoder to record .wmv files, and RealProducer to record .rm files.
• Does VGA2USB LR, HR or Pro compression algorithms degrade the quality of output?

  • No. All these devices uses advanced compression algorithms that helps to to achieve high transfer rates without loss of image quality.

• Does VGA2USB, LR, HR and PRO support capture to Mac OS?
  • Yes, all these devices are fully compatible with Mac OS 10.3.x and higher and support QuickTime API.
     
• Additional Resources:
  • VGA2USB Review and Information Article
• Please contact us if your question or concern is not addressed in this list.