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

Bookends 13.2.5 - Reference management a...
Bookends is a full-featured bibliography/reference and information-management system for students and professionals. Bookends uses the cloud to sync reference libraries on all the Macs you use.... Read more
Quicken 2019 5.11.2 - Complete personal...
Quicken makes managing your money easier than ever. Whether paying bills, upgrading from Windows, enjoying more reliable downloads, or getting expert product help, Quicken's new and improved features... Read more
Dashlane 6.1927.0 - Password manager and...
Dashlane is an award-winning service that revolutionizes the online experience by replacing the drudgery of everyday transactional processes with convenient, automated simplicity - in other words,... Read more
Capo 3.7.4 - Slow down and learn to play...
Capo lets you slow down your favorite songs so you can hear the notes and learn how they are played. With Capo, you can quickly tab out your songs atop a highly-detailed OpenCL-powered spectrogram... Read more
BetterTouchTool 3.153 - Customize multi-...
BetterTouchTool adds many new, fully customizable gestures to the Magic Mouse, Multi-Touch MacBook trackpad, and Magic Trackpad. These gestures are customizable: Magic Mouse: Pinch in / out (zoom)... Read more
calibre 3.46.0 - Complete e-book library...
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
Firefox 68.0.1 - Fast, safe Web browser.
Firefox offers a fast, safe Web browsing experience. Browse quickly, securely, and effortlessly. With its industry-leading features, Firefox is the choice of Web development professionals and casual... Read more
Vivaldi 2.6.1566.49 - An advanced browse...
Vivaldi is a browser for our friends. We live in our browsers. Choose one that has the features you need, a style that fits and values you can stand by. From the look and feel, to how you interact... Read more
Daylite 6.7.3.1 - Dynamic business organ...
Daylite helps businesses organize themselves with tools such as shared calendars, contacts, tasks, projects, notes, and more. Enable easy collaboration with features such as task and project... Read more
Vivaldi 2.6.1566.49 - An advanced browse...
Vivaldi is a browser for our friends. We live in our browsers. Choose one that has the features you need, a style that fits and values you can stand by. From the look and feel, to how you interact... Read more

Latest Forum Discussions

See All

Void Tyrant guide - Tips and tricks for...
Void Tyrant continues to get a lot of play in these parts. Probably because the game is just so deep and varied. The next stop on our guide series for Void Tyrant is class-specific guides. First up is the Knight, as it’s the first class anyone has... | Read more »
Summon beasts and battle evil in epic re...
Imagine a tale of conlict between factions of good and evil, where rogueish heroes summon beasts to aid them in them in warfare and courageously battle dragons over fields of scorched earth and brimstone - that's exactly the essence of epic fantasy... | Read more »
Upcoming visual novel Arranged shines a...
If you’re in the market for a new type of visual novel designed to inform and make you think deeply about its subject matter, then Arranged by Kabuk Games could be exactly what you’re looking for. It’s a wholly unique take on marital traditions in... | Read more »
TEPPEN guide - The three best decks in T...
TEPPEN’s unique take on the collectible card game genre is exciting. It’s just over a week old, but that isn’t stopping lots of folks from speculating about the long-term viability of the game, as well as changes and additions that will happen over... | Read more »
Intergalactic puzzler Silly Memory serve...
Recently released matching puzzler Silly Memory is helping its fans with their intergalactic journeys this month with some very special offers on in-app purchases. In case you missed it, Silly Memory is the debut title of French based indie... | Read more »
TEPPEN guide - Tips and tricks for new p...
TEPPEN is a wild game that nobody asked for, but I’m sure glad it exists. Who would’ve thought that a CCG featuring Capcom characters could be so cool and weird? In case you’re not completely sure what TEPPEN is, make sure to check out our review... | Read more »
Dr. Mario World guide - Other games that...
We now live in a post-Dr. Mario World world, and I gotta say, things don’t feel too different. Nintendo continues to squirt out bad games on phones, causing all but the most stalwart fans of mobile games to question why they even bother... | Read more »
Strategy RPG Brown Dust introduces its b...
Epic turn-based RPG Brown Dust is set to turn 500 days old next week, and to celebrate, Neowiz has just unveiled its biggest and most exciting update yet, offering a host of new rewards, increased gacha rates, and a brand new feature that will... | Read more »
Dr. Mario World is yet another disappoin...
As soon as I booted up Dr. Mario World, I knew I wasn’t going to have fun with it. Nintendo’s record on phones thus far has been pretty spotty, with things trending downward as of late. [Read more] | Read more »
Retro Space Shooter P.3 is now available...
Shoot-em-ups tend to be a dime a dozen on the App Store, but every so often you come across one gem that aims to shake up the genre in a unique way. Developer Devjgame’s P.3 is the latest game seeking to do so this, working as a love letter to the... | Read more »

Price Scanner via MacPrices.net

Flash sale! New 11″ 1TB WiFi iPad Pros for th...
Amazon has the 11″ 1TB WiFi iPad Pro on sale today for only $1199.99 including free shipping. Their price is $350 off Apple’s MSRP for this model, and it’s the lowest price ever for a 1TB 11″ iPad... Read more
Weekend Deal: 2018 13″ MacBook Airs starting...
B&H Photo has clearance 2018 13″ MacBook Airs available starting at only $999 with all models now available for $200 off Apple’s original MSRP. Overnight shipping, or expedited shipping, is free... Read more
Apple has clearance 10.5″ iPad Pros available...
Apple has Certified Refurbished 2017 10.5″ iPad Pros available starting at $469. An Apple one-year warranty is included with each iPad, outer shells are new, and shipping is free: – 64GB 10″ iPad Pro... Read more
Apple restocks refurbished iPad mini 4 models...
Apple has restocked Certified Refurbished 32GB iPad mini 4 WiFi models for $229 shipped. That’s $70 off original MSRP for the iPad mini 4. Space Gray, Silver, and Gold colors are available. Read more
Apple, Yet Again, Is Missing An Ultraportable...
EDITORIAL: 07.19.19 Prior to the decision made by Apple earlier this month to retire the thin and light MacBook model with a 12-inch retina display, the Cupertino, California-based company offered,... Read more
Verizon is offering a 50% discount on iPhone...
Verizon is offering 50% discounts on Apple iPhone 8 and iPhone 8 Plus models though July 24th, plus save 50% on activation fees. New line required. The fine print: “New device payment & new... Read more
Get a new 21″ iMac for under $1000 today at t...
B&H Photo has new 21″ Apple iMacs on sale for up to $100 off MSRP with models available starting at $999. These are the same iMacs offered by Apple in their retail and online stores. Shipping is... Read more
Clearance 2017 15″ 2.8GHz Touch Bar MacBook P...
Apple has Certified Refurbished 2017 15″ 2.8GHz Space Gray Touch Bar MacBook Pros available for $1809. Apple’s refurbished price is currently the lowest available for a 15″ MacBook Pro. An standard... Read more
Clearance 12″ 1.2GHz MacBook on sale for $899...
Focus Camera has clearance 12″ 1.2GHz Space Gray MacBooks available for $899.99 shipped. That’s $400 off Apple’s original MSRP. Focus charges sales tax for NY & NJ residents only. Read more
Get a new 2019 13″ 2.4GHz 4-Core MacBook Pro...
B&H Photo has new 2019 13″ 2.4GHz MacBook Pros on sale for up to $150 off Apple’s MSRP. Overnight shipping is free to many addresses in the US: – 2019 13″ 2.4GHz/256GB 6-Core MacBook Pro Silver... Read more

Jobs Board

Best Buy *Apple* Computing Master - Best Bu...
**707083BR** **Job Title:** Best Buy Apple Computing Master **Job Category:** Sales **Location Number:** 000045-Rockford-Store **Job Description:** **What does a Read more
Geek Squad *Apple* Master Consultation Agen...
**702908BR** **Job Title:** Geek Squad Apple Master Consultation Agent **Job Category:** Services/Installation/Repair **Location Number:** 000360-Williston-Store Read more
Best Buy *Apple* Computing Master - Best Bu...
**711023BR** **Job Title:** Best Buy Apple Computing Master **Job Category:** Sales **Location Number:** 000012-St Cloud-Store **Job Description:** **What does a Read more
*Apple* Systems Architect/Engineer, Vice Pre...
…its vision to be the world's most trusted financial group. **Summary:** Apple Systems Architect/Engineer with strong knowledge of products and services related to Read more
Best Buy *Apple* Computing Master - Best Bu...
**696259BR** **Job Title:** Best Buy Apple Computing Master **Job Category:** Store Associates **Location Number:** 001076-Temecula-Store **Job Description:** The Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.