Using computer output as a video source
There are various times when it can be useful to use the output of a computer as a video source, including
- feeding an external video recorder, or connecting to a conventional TV Monitor (eg. from an Output module)
- sending the output of one computer to the video input of another (eg. for capturing Powerpoint presentations)
There are different hardware devices available, depending on the type of output connection available on the PC.
For VGA output, there are several low-cost options that can connected using a cable splitter so that the VGA output from a computer is routed both to a projector/second monitor, and to the screen grabber. Many of these use a simple USB interface into the VidBlaster computer.
There are higher cost options in the form of PCI cards that can be used to capture VGA output with a higher framerate, like the Startech PEXHDCAP or Magewell X1204XE.
|Note - there’s a limit to the length of cable through which an analogue VGA signal can be run. In most cases it is better to put the frame grabber close to the presenter's computer, and use an active USB cable to connect the frame grabber to the VidBlaster Computer. Also consider the number of USB channels available on the VidBlaster Computer. There's a discussion on this in the article on connection types.|
Examples of remote VGA capture devices:
Examples of VGA to SD video converters:
Examples of VGA to HDMI converters:
For DVI output, there are products available that can convert the DVI output into analogue video or an SDI video stream. These devices can handle normal video frame rates, and the resulting SDI stream can be run over longer distances to the VidBlaster computer, typically 50-100M or more.
Examples of SDI capture cards:
DisplayPort is a digital output, used among others on Lenovo Laptops and Apple Macs. There are low-cost adapters/cables available that can convert DisplayPort output into a HDMI stream. Make sure you get an active adaptor (not a passive one).
HDMIHDMI is getting increasingly popular with newer laptops and video cards on desktops. Many DVI outputs are also capable of generating HDMI-compatible output via a simple passive adaptor/cable. There are also projectors with HDMI input that are coming into use.
There are HDMI splitters available so that the HDMI output can be sent both to a projector/monitor and to a capture card in the VidBlaster computer. HDMI capture cards allow for high frame rates at HD resolutions, but there are limits on maximum HDMI cable length because it was designed for domestic/consumer installations. For professional environments, HD-SDI is the preferred signal format, allowing for much longer cable runs over single-core coaxial cable.
Examples of HDMI Capture cards:
|See also - Using desktop capture software and LAN cabling for Streaming a remote desktop into VidBlaster.|