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

Duplicate Annihilator 5.7.5 - Find and d...
Duplicate Annihilator takes on the time-consuming task of comparing the images in your iPhoto library using effective algorithms to make sure that no duplicate escapes. Duplicate Annihilator... Read more
BusyContacts 1.0.2 - Fast, efficient con...
BusyContacts is a contact manager for OS X that makes creating, finding, and managing contacts faster and more efficient. It brings to contact management the same power, flexibility, and sharing... Read more
Capture One Pro 8.2.0.82 - RAW workflow...
Capture One Pro 8 is a professional RAW converter offering you ultimate image quality with accurate colors and incredible detail from more than 300 high-end cameras -- straight out of the box. It... Read more
Backblaze 4.0.0.872 - Online backup serv...
Backblaze is an online backup service designed from the ground-up for the Mac.With unlimited storage available for $5 per month, as well as a free 15-day trial, peace of mind is within reach with... Read more
Little Snitch 3.5.2 - Alerts you about o...
Little Snitch gives you control over your private outgoing data. Track background activity As soon as your computer connects to the Internet, applications often have permission to send any... Read more
Monolingual 1.6.4 - Remove unwanted OS X...
Monolingual is a program for removing unnecesary language resources from OS X, in order to reclaim several hundred megabytes of disk space. If you use your computer in only one (human) language, you... Read more
CleanApp 5.0 - Application deinstaller a...
CleanApp is an application deinstaller and archiver.... Your hard drive gets fuller day by day, but do you know why? CleanApp 5 provides you with insights how to reclaim disk space. There are... Read more
Fantastical 2.0 - Create calendar events...
Fantastical is the Mac calendar you'll actually enjoy using. Creating an event with Fantastical is quick, easy, and fun: Open Fantastical with a single click or keystroke Type in your event details... Read more
Cocktail 8.2 - General maintenance and o...
Cocktail is a general purpose utility for OS X that lets you clean, repair and optimize your Mac. It is a powerful digital toolset that helps hundreds of thousands of Mac users around the world get... Read more
Direct Mail 4.0.4 - Create and send grea...
Direct Mail is an easy-to-use, fully-featured email marketing app purpose-built for OS X. It lets you create and send great looking email campaigns. Start your newsletter by selecting from a gallery... Read more

Fast & Furious: Legacy's Creati...
| Read more »
N-Fusion and 505's Ember is Totally...
| Read more »
These are All the Apple Watch Apps and G...
The Apple Watch is less than a month from hitting store shelves, and once you get your hands on it you're probably going to want some apps and games to install. Fear not! We've compiled a list of all the Apple Watch apps and games we've been able to... | Read more »
Appy to Have Known You - Lee Hamlet Look...
Being at 148Apps these past 2 years has been an awesome experience that has taught me a great deal, and working with such a great team has been a privilege. Thank you to Rob Rich, and to both Rob LeFebvre and Jeff Scott before him, for helping me... | Read more »
Hands-On With Allstar Heroes - A Promisi...
Let’s get this out of the way quickly. Allstar Heroes looks a lot like a certain other recent action RPG release, but it turns out that while it’s not yet available here, Allstar Heroes has been around for much longer than that other title. Now that... | Read more »
Macho Man and Steve Austin Join the Rank...
WWE Immortals, by Warner Bros. Interactive Entertainment and WWE, has gotten a superstar update. You'll now have access to Macho Man Randy Savage and Steve Austin. Both characters have two different versions: Macho Man Randy Savage Renegade or Macho... | Read more »
Fearless Fantasy is Fantastic for the iF...
I actually had my first look at Fearless Fantasy last year at E3, but it was on a PC so there wasn't much for me to talk about. But now that I've been able to play with a pre-release version of the iOS build, there's quite a bit for me to talk... | Read more »
MLB Manager 2015 (Games)
MLB Manager 2015 5.0.14 Device: iOS Universal Category: Games Price: $4.99, Version: 5.0.14 (iTunes) Description: Guide your favorite MLB franchise to glory! MLB Manager 2015, officially licensed by MLB.com and based on the award-... | Read more »
Breath of Light (Games)
Breath of Light 1.0.1421 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0.1421 (iTunes) Description: Hold a quiet moment. Breath of Light is a meditative and beautiful puzzle game with a hypnotic soundtrack by... | Read more »
WWE WrestleMania Tags into the App Store
Are You ready to rumble? The official WWE WrestleMania app, by World Wrestling Entertainment, is now available. Now you can get all your WrestleMania info in one place before anyone else. The app offers details on superstar signings, interactive... | Read more »

Price Scanner via MacPrices.net

13-inch 2.5GHz MacBook Pro (refurbished) avai...
The Apple Store has Apple Certified Refurbished 13″ 2.5GHz MacBook Pros available for $829, or $270 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free: - 13″ 2.... Read more
Save up to $80 on iPad Air 2s, NY tax only, f...
 B&H Photo has iPad Air 2s on sale for $80 off MSRP including free shipping plus NY sales tax only: - 16GB iPad Air 2 WiFi: $469.99 $30 off - 64GB iPad Air 2 WiFi: $549.99 $50 off - 128GB iPad... Read more
iMacs on sale for up to $205 off MSRP
B&H Photo has 21″ and 27″ iMacs on sale for up to $205 off MSRP including free shipping plus NY sales tax only: - 21″ 1.4GHz iMac: $1019 $80 off - 21″ 2.7GHz iMac: $1189 $110 off - 21″ 2.9GHz... Read more
Färbe Technik Offers iPhone Battery Charge LI...
Färbe Technik, which manufactures and markets of mobile accessories for Apple, Blackberry and Samsung mobile devices, is offering tips on how to keep your iPhone charged while in the field: •... Read more
Electronic Recyclers International CEO Urges...
Citing a recent story on CNBC about concerns some security professionals have about the forthcoming Apple Watch, John Shegerian, Chairman and CEO of Electronic Recyclers International (ERI), the... Read more
Save up to $380 with Apple refurbished iMacs
The Apple Store has Apple Certified Refurbished iMacs available for up to $380 off the cost of new models. Apple’s one-year warranty is standard, and shipping is free: - 27″ 3.5GHz 5K iMac – $2119 $... Read more
Mac minis on sale for up to $75 off, starting...
MacMall has Mac minis on sale for up to $75 off MSRP including free shipping. Their prices are the lowest available for these models from any reseller: - 1.4GHz Mac mini: $459.99 $40 off - 2.6GHz Mac... Read more
College Student Deals: Additional $50 off Mac...
Take an additional $50 off all MacBooks and iMacs at Best Buy Online with their College Students Deals Savings, valid through April 11, 2015. Anyone with a valid .EDU email address can take advantage... Read more
Mac Pros on sale for up to $260 off MSRP
B&H Photo has Mac Pros on sale for up to $260 off MSRP. Shipping is free, and B&H charges sales tax in NY only: - 3.7GHz 4-core Mac Pro: $2799, $200 off MSRP - 3.5GHz 6-core Mac Pro: $3719.99... Read more
13-inch 2.5GHz MacBook Pro on sale for $100 o...
B&H Photo has the 13″ 2.5GHz MacBook Pro on sale for $999 including free shipping plus NY sales tax only. Their price is $100 off MSRP. Read more

Jobs Board

DevOps Software Engineer - *Apple* Pay, iOS...
**Job Summary** Imagine what you could do here. At Apple , great ideas have a way of becoming great products, services, and customer experiences very quickly. Bring Read more
*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
Sr. Technical Services Consultant, *Apple*...
**Job Summary** Apple Professional Services (APS) has an opening for a senior technical position that contributes to Apple 's efforts for strategic and transactional Read more
Lead *Apple* Solutions Consultant - Retail...
**Job Summary** Job Summary The Lead ASC is an Apple employee who serves as the Apple business manager and influencer in a hyper-business critical Reseller's store Read more
*Apple* Pay - Site Reliability Engineer - Ap...
**Job Summary** Imagine what you could do here. At Apple , great ideas have a way of becoming great products, services, and customer experiences very quickly. Bring Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.