TweetFollow Us on Twitter

Easily capture video from any VGA or DVI device

Volume Number: 23 (2007)
Issue Number: 11
Column Tag: Media

Easily capture video from any VGA or DVI device

Discover how to grab raw video frames and stream them to your preferred capture utility

by Joe Froehlich

How did you do that?

At one point or another, you've most certainly used the infamous [Command] [Shift] [4] key sequence to take a screen shot of an application window or a dialog box that reports a particular error. And, if you prepare training or technical documentation on a regular basis, you've probably graduated to a more sophisticated screen capture utility like Ambrosia Software's SnapzPro X.

But, how do you capture the screen that appears when you launch the Mac OS X Startup Manager, shown in Figure 1, for example? Furthermore, what if you need to record a movie of the entire boot sequence for troubleshooting or training purposes?


Figure 1: Mac OS X Startup Manager

You can't use the tools we've just described because the operating system isn't loaded yet and there's no way to launch a capture utility. In this article, we'll show you how to capture not only static images like Startup Manager, but entire video streams from any VESA-compatible VGA or DVI source, including industrial, scientific, and forensics equipment.

Discover the magic

To acquire images and data streams like those we're discussing here, you typically need to use a frame grabber that captures the raw data generated at the output of a VGA or DVI source, regardless of whether the source is a computer or some other type of equipment. Most frame grabbers are available only as internal PCI expansion cards. Unfortunately, this limits the type of equipment you can use to capture source content. On the other hand, Epiphan Systems, Inc. provides an external USB solution, obviating the need to rely on internal expansion cards for this task and providing convenient portability at the same time.

Epiphan's product family, appropriately named VGA2USB, includes several distinct devices, including the LR, HR, and Pro models, which differ primarily in the image resolutions and frame rates they support. A DVI2USB product is also available to support DVI source equipment. A comparative summary of all product specifications is available via the Frame Grabbers link on Epiphan's website (www.epiphan.com). Figure 2 illustrates the standard version of VGA2USB; the other devices look similar but differ in the color of their respective enclosures.


Figure 2: VGA2USB frame grabber with VGA port (left) and mini-USB port (right)

Plug it in

Prior to connecting the product to your equipment, you need to install the streaming software on a system you want to use as a capture workstation; the source equipment doesn't require any software. The streaming software includes the following items, all included in a single installation package:

The USB device driver

The v2u capture and diagnostics utility (installed in /usr/bin/)

The vdig QuickTime digitizer (installed in /Library/QuickTime/QuickVGA2USB.component)

To install the software, download the latest version of the installation package from www.epiphan.com/downloads/, unpack it, and run the installer. Once the installation is complete, connect the source equipment to the VGA2USB device, and the VGA2USB device to a USB 2.0 port on your capture workstation, as shown in Figure 3.


Figure 3: Connecting VGA2USB to your equipment

If desired, you can install either a passive or an active signal splitter to simultaneously display the VGA or DVI output from the source on a secondary display. Doing so helps you monitor the source image during a capture session, for example.

Next, open System Profiler and expand the USB device tree. You'll see the VGA2USB device listed, as shown in Figure 4. Before continuing, make sure the device is connected to a USB 2.0 port.


Figure 4: The VGA2USB device as it appears in System Profiler

And finally, open a Terminal session and launch /usr/bin/v2u. With no arguments, the v2u utility reports the detected signal, as shown in Figure 5; otherwise it reports no signal detected. For a complete list of arguments, enter v2u h.


Figure 5: Using the v2u diagnostic utility.

Make a movie

While you can use the v2u utility to perform diagnostics and capture individual frames, you'll probably want to use an Aqua application, such as QuickTime Pro, to capture video streams. There are several other applications that you can use as well; for example, VGA2USB is certified to work with Adobe Premiere on both Windows and Mac platforms. Other third-party applications include Vara Software's Wirecast and Videocue as well as Boinx Software's iStop Motion.

Because each capture application offers different features and capabilities, it isn't practical to discuss them all here. For the purpose of this article, we'll just give you a quick tour. In Figure 6, for example, the video output of our server machine is being streamed (via VGA2USB Pro) to Wirecast, which is running on our capture workstation. When we click the Record button on the toolbar, Wirecast records a movie of our login session. We can then use QuickTime Player to play back the movie. We could also use Wirecast to broadcast the stream if desired.


Figure 6: Capturing a video stream in Wirecast

Need a Windows solution?

If you wish, you can use a Windows platform to capture your streams as well. Epiphan provides its own Windows capture application, which is installed by default when you install the drivers on a Windows machine. Of course, there are also several third-party applications that work with it as well. Figure 7, for example, shows a PC BIOS screen captured using Epiphan's VGA2USB capture utility.


Figure 7: Capturing a PC BIOS screen

"Big deal," you say?

At this point, you may be asking yourself, "Why not just use VNC, ARD, or some other remote monitoring solution?" The answer to this question is that, depending on the screen you need to acquire, these services may only be available much later in the boot process. Furthermore, they require you to alter the source by installing the appropriate software component. You can't use these solutions to capture a screen like Startup Manager or a PC BIOS, much less the video output of a non-computer device.

While our demonstration illustrates a computer technology application, there are other environments in which a frame grabber is not only useful but is actually required, depending on the screen you need to acquire. Figure 8, for example, shows the output of sonogram. Other application environments include:

Presentations to remote audiences

Medical diagnostic imaging

Distance learning

Scientific device screen acquisition

Courtroom evidence recording

Security and surveillance

Industrial control system monitoring


Figure 8: Acquiring a screen from a medical imaging device

In short, if you have a device that generates a VGA or DVI signal and you need to capture its output without altering the source equipment (critical for computer forensics, for example), you need a frame grabber.

Conclusion

In this article, we presented a method for capturing static images as well as video streams from devices that are otherwise inaccessible using traditional screen capture utilities. Hopefully, you've learned something new and, if you have such needs, you'll undoubtedly want to explore solutions like this further.


Joe is a technical writer and instructional designer with extensive experience on both Windows and Mac platforms. He's a member of the Apple Consultants Network, the Microsoft Partner Program, and the IEEE Computer Society. You can reach him at froejoe@gmail.com.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Apple iOS 8.1.3 - The latest version of...
The latest version of iOS can be downloaded through iTunes. Apple iOS 8 comes with big updates to apps you use every day, like Messages and Photos. A whole new way to share content with your family.... Read more
SpamSieve 2.9.19 - Robust spam filter fo...
SpamSieve is a robust spam filter for major email clients that uses powerful Bayesian spam filtering. SpamSieve understands what your spam looks like in order to block it all, but also learns what... Read more
RapidWeaver 6.0.5 - Create template-base...
RapidWeaver is a next-generation Web design application to help you easily create professional-looking Web sites in minutes. No knowledge of complex code is required, RapidWeaver will take care of... Read more
Duet 1.2.2 - Use your iPad as an externa...
Duet is the first app that allows you to use your iDevice as an extra display for your Mac using the Lightning or 30-pin cable. Note: This app requires a $14.99 iOS companion app. Version 1.2.2:... Read more
Alfred 2.6 - Quick launcher for apps and...
Alfred is an award-winning productivity application for OS X. Alfred saves you time when you search for files online or on your Mac. Be more productive with hotkeys, keywords, and file actions at... Read more
1Password 5.1 - Powerful password manage...
1Password is a password manager that uniquely brings you both security and convenience. It is the only program that provides anti-phishing protection and goes beyond password management by adding Web... Read more
GarageSale 6.9.2 - Create outstanding eB...
GarageSale is a slick, full-featured client application for the eBay online auction system. Create and manage your auctions with ease. With GarageSale, you can create, edit, track, and manage... Read more
calibre 2.17 - Complete e-library manage...
Calibre is a complete e-book library manager. Organize your collection, convert your books to multiple formats, and sync with all of your devices. Let Calibre be your multi-tasking digital librarian... Read more
OmniGraffle Pro 6.1.2 - Create diagrams,...
OmniGraffle Pro helps you draw beautiful diagrams, family trees, flow charts, org charts, layouts, and (mathematically speaking) any other directed or non-directed graphs. We've had people use... Read more
OmniGraffle 6.1.2 - Create diagrams, flo...
OmniGraffle helps you draw beautiful diagrams, family trees, flow charts, org charts, layouts, and (mathematically speaking) any other directed or non-directed graphs. We've had people use Graffle to... Read more

New WOTA: U-Boat Compass ‘Wets’ Your App...
New WOTA: U-Boat Compass ‘Wets’ Your Appetite for WOTA: Wolves of the Atlantic. Posted by Jessica Fisher on January 27th, 2015 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Warship Solitaire Review
Warship Solitaire Review By Nadia Oxford on January 27th, 2015 Our Rating: :: A WAR OF NUMBERSUniversal App - Designed for iPhone and iPad Warship Solitaire might lack frills and looks, but it offers some thought provoking... | Read more »
Keep Track of Your Hectic Work Schedule...
Keep Track of Your Hectic Work Schedule With Shifts Posted by Jessica Fisher on January 27th, 2015 [ permalink ] iPhone App - Designed for the iPhone, compatible with the iPad | Read more »
All Star Quarterback Review
All Star Quarterback Review By Campbell Bird on January 27th, 2015 Our Rating: :: PLAY YOUR PARTUniversal App - Designed for iPhone and iPad Train your way to the Super Bowl in this free-to-play sports management game.   | Read more »
Sentinel 4: Dark Star Adds New Campaign...
Sentinel 4: Dark Star Adds New Campaign and More Posted by Ellis Spice on January 27th, 2015 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Wheel & Deal Review
Wheel & Deal Review By Tre Lawrence on January 27th, 2015 Our Rating: :: SIMPLE FUNUniversal App - Designed for iPhone and iPad A simple arcade shooter that has a retro feel.   | Read more »
Join the NAVY in a Big New Update for WW...
Join the NAVY in a Big New Update for WW2: Sandbox. Strategy & Tactics Posted by Jessica Fisher on January 27th, 2015 [ permalink ] Universal App - Designed for iPhone and iPad | Read more »
Earthworm Alchemy Review
Earthworm Alchemy Review By Campbell Bird on January 27th, 2015 Our Rating: :: FEED THE WORMUniversal App - Designed for iPhone and iPad Feed this funny looking worm and dodge bombs in this charming, free-to-play arcade game.   | Read more »
Graphic Novel App netwars – The Butterfl...
Graphic Novel App netwars – The Butterfly Attack has Received Some New Episodes Posted by Jessica Fisher on January 27th, 2015 [ permalink ] | Read more »
DataVault Password Manager Review
DataVault Password Manager Review By Jennifer Allen on January 27th, 2015 Our Rating: :: SECURE DATA STORAGEUniversal App - Designed for iPhone and iPad Store your passwords and other sensitive information safely, thanks to... | Read more »

Price Scanner via MacPrices.net

Save up to $340 on iMacs with Apple Certified...
The Apple Store has Apple Certified Refurbished iMacs available for up to $340 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free. These are the best prices on... Read more
AppleCare Protection Plans on sale for up to...
B&H Photo has 3-Year AppleCare Warranties on sale for up to $105 off MSRP including free shipping plus NY sales tax only: - Mac Laptops 15″ and Above: $244 $105 off MSRP - Mac Laptops 13″ and... Read more
Apple refurbished Time Capsules available sta...
The Apple Store has certified refurbished Time Capsules available for up to $60 off MSRP. Apple’s one-year warranty is included with each Time Capsule, and shipping is free: - 2TB Time Capsule: $255... Read more
3TB AirPort Time Capsule on sale for $349, $5...
B&H Photo has 3TB AirPort Time Capsules on sale for $349 including free shipping plus NY sales tax only. Their price is $50 off MSRP, and it’s the lowest price available for this model (except... Read more
16GB iPad Air 2 on sale for $446, save $53
Walmart has 16GB WiFi iPad Air 2s on sale for $53 off MSRP on their online store. Choose free shipping or free local store pickup (if available). Sale prices available for online orders only, in-... Read more
Save up to $300 on a new Mac, $30 on an iPad,...
Purchase a new Mac or iPad at The Apple Store for Education and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free,... Read more
MasterCard Brings Contactless Payment, Apple...
MasterCard, the official card of the Waste Management Phoenix Open, and the PGA TOUR are bringing the latest payment technology to the spectator experience with the introduction of contactless... Read more
Petitioning Dropbox For Mac OS X 10.4 and 10....
Last week Dropbox announced to its users that app support for Mac OS X 10.4 and 10.5 will end May 18 — disappointing news for those of us who are still getting useful service out of older PPC Macs... Read more
Stop Street Harassment, Bullying, and Assault...
The STOP-ATTACK (http://www.stop-attack.com) app will leverage smartphone technology to make the world a safer place. Whether it’s bullying, street harassment or something even more sinister, the app... Read more
Stir Kinetic Desk M1 Standing Or Sitting Desk...
The age of the standing desk is upon us, and according to medical research, it’s arriving none too soon. The World Health Organization (WHO), reports that 60 to 85 percent of people worldwide lead... Read more

Jobs Board

*Apple* Solutions Consultant - Retail Sales...
**Job Summary** As an Apple Solutions Consultant (ASC) you are the link between our customers and our products. Your role is to drive the Apple business in a retail Read more
*Apple* Solutions Consultant - Retail Sales...
As an ambassador of the Apple brand, the ASC is accountable for driving sales performance by: Connecting with customers. Discovering customers' needs and values. Showing Read more
*Apple* Solutions Consultant- Retail Sales -...
**Job Summary** The ASC is an Apple employee who serves as an Apple brand ambassador and influencer in a Resellers store. The ASCs role is to grow Apple product Read more
Detailer *Apple* Ford Body Shop / Collision...
Apple Automotive is one of the fastest growing dealer…and it shows. Consider making the switch to the Apple Automotive Group today! At Apple Automotive , Read more
*Apple* Acura/Subaru Service Technicians - A...
Apple Automotive is one of the fastest growing dealer…and it shows. Consider making the switch to the Apple Automotive Group today! At Apple Automotive , Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.