How we capture hi-def Vista video streams
We've developed a pretty novel way to capture presentation and demo content from Vista here at the PAC. There are a couple of old ways that don't work quite well, maybe you've used them:
- Convert the VGA signal to composite video.
- Use a continuous screen capture utility like Windows Media Encoder's screen capture mode.
Method one still sort of works, but since the base resolution is going to be 720x480 at best; it really doesn't work all that well anymore. It also destroys color fidelity and makes text unreadable. Vista has such a great look that destroying it using a 1950s transport medium is quite the crime.
Method two just doesn't work anymore on Vista. The DirectX based GPU acceleration features of Vista either bypass the GDI based capture methods OR it drives the performance the graphics to zero as each rendered frame is pushed to the GDI layer for capture.
We did some web searching and found a very novel piece of technology from a company named Epiphan. They create several products that sample VGA and DVI signals in real time and then transmits them as JPGs over USB to a capture system. We use the VGA2USB product and the newer DVI2USB product. The DVI2USB product is our current favorite with better drivers and better performance. We've used the VGA2USB product for quite sometime now and we've notice that it occasionally blue screens when we stop capturing the streams from Windows Media Encoder. Because it’s a stream, we never lose any presentation data because it was already committed to the disk, but it is a bit disconcerting. Regardless, both units have worked liked champs and have captured hundreds of hours of high resolution video from the screens of presenter's laptops.
If you do go this route, you should probably invest in a good distribution amplifier to split the VGA signal cleanly. We like the Kramer VP300 but you can get cheaper units from companies like IOGear. Try to stay away from the simplistic “split VGA” cable since the loss of signal will put a dent in your captured stream.
