Your Complete Guide to VGA and VGA Capture
Whether your application involves creating IT instructional manuals, recording from high resolution security systems, sharing a presentation with people from around the world, or printing handouts directly from any computer screen, you are looking at VGA video capture or VGA signal capture as a mean to achieving these goals. This article will explain in-depth how VGA signal capture works and what you need to know in order to capture such a signal.
The VGA Plug
Unlike DVI or HDMI, which are both digital standards, a VGA signal is purely analog. The differences between VGA, DVI, and HDMI are described in detail in this article.
“VGA” is short for Video Graphics Array and has been the most common connector/plug for analog video on computer equipment and various electronics with an analog video output since the introduction of personal computers (PCs). VGA carries a RGB (red-green-blue) signal and is sometimes referred to as “D-Sub” due to its’ 15-pin “subminiature” connector. The term “VGA” also refers to the VGA standard graphics resolution – 640×480 pixels.
A detailed VGA pinout is shown below to help advanced users understand how VGA works. Source.
VGA Video Connector Pinout
| Pin # | Signal Name |
|---|---|
| 1 | Red |
| 2 | Green |
| 3 | Blue |
| 4 | No Connect |
| 5 | Ground |
| 6 | Ground |
| 7 | Ground |
| 8 | Ground |
| 9 | No Connect |
| 10 | Ground |
| 11 | No Connect |
| 12 | DDC DAT |
| 13 | Horizontal Synchronization |
| 14 | Vertical Synchronization |
| 15 | DDC Clock |
VGA Frame Grabbers and How They Work
The only true way to capture and record a VGA signal is through a VGA-compatible frame grabber. A VGA frame grabber can be defined as a device that proccesses analog VGA signals and converts them into digital signals readable by computer equipment. While frame grabbers are described in slightly higher detain in this Wikipedia article, these three main internal components determine a VGA frame grabber’s performance:
- ADC (analog-to-digital) converter. This is the circuit that transforms the analog signal coming from the source VGA signal into a digital stream that can be read by the target computer.
- RAM (random-access memory). Also referred to as buffer memory, this memory is vital in storing the captured image for a short period of time on board the actual frame grabber.
- FPGA (field-programmable gate array). This is the heart of the frame grabber and is analogous to a processor inside a PC. It is a part that is entirely programmed by the manufacturer of the frame grabber.
Some frame grabbers, like the PixelSmart VGA Master have no on-board RAM buffer memory. This fact alone, besides leading to a lower-quality image, lowers the maximum possible capture rate (also referred to as frame rate) achievable by the frame grabber. Frame grabbers without on-board RAM are sufficient for the capture of presentations with lots of static slides or any other static imagery, like capturing screenshots from the computer’s BIOS. On the other hand, if you are capturing a high-resolution image and/or are capturing from a source with a high frame rate, like a video game console (ie XBOX 360) or medical equipment (ie: ultrasound), a frame grabber with at least 16MB RAM would be preferred. The VGA2USB Pro by Epiphan Systems, for example, has 32MB RAM memory and is able to capture at a whopping 60 frames per second in some resolutions.
PixelSmart’s Internal PCI VGA-Master
Epiphan Systems’ external USB-based VGA2USB Pro frame grabber
While RAM is important in defining the characteristics of a frame grabber and the quality of the image it outputs, another important factor is the way that the FPGA, or processor, is programmed. You will notice that the higher-end frame grabbers, like the VGA2USB Pro pictured above, have built-in features that some of the more basic frame grabbers, like the PixelSmart, do not have. A quick look at the Epiphan Systems webpage reveals the following features programmed via the FPGA processor: On-board cropping, Color space conversion, USB Transfer Accelerator™, Compression Booster Filters™. All of these software/firmware features allow the frame grabber to achieve extremely high quality and transfer rates without increasing the frame grabber’s size.
Please refer to our complete Frame Grabber Specifications Comparison Table for detailed and complete specifications on every VGA frame grabber on the market.
Applications for Frame Grabbers
Frame Grabbers, while being a niche product, have many practical uses in today’s IT-oriented business environment. The five most common and prominent uses are described in detail in our Top 5 Uses for High Resolution Frame Grabbers You Should Know About article. From the gaming industry to the military, frame grabbers are used accross many fields related to computer technology. To give you a general idea, some industry-specific uses for high resolution VGA frame grabbers are described below.
Computer Console Gaming
Microsoft’s X-BOX 360 gaming console has the ability to output its images via VGA or DVI. This means that a VGA frame grabber can be used to capture and record the gameplay from this game console, and even broadcast the gameplay live over the internet for other viewers to see.
The diagram above explains how to connect an X-BOX 360 to a frame grabber for recording and broadcasting the gameplay. The X-BOX’s VGA cable is connected to a VGA splitter’s input, from which one VGA output goes to the TV, and the other to the frame grabber-equipped computer. The image can then be broadcasted to the internet using the computer.
Presentation, Conference Broadcasting and Recording
In today’s globalized business world, businesses often have partners in many different countries. When conducting an online meeting or presentation, the presenter often has the need to share his screen with viewers around the world. For this exact reason, VGA frame grabbers are useful. They allow the presenter to not only share an image from a projector, but also from a BIOS screen, an ATM machine, a RADAR device, a medical ultrasound device, a security system, or even an electronic microscope. Most of these VGA sources are not able to be broadcasted in real-time with the use of traditional software sources, and frame grabbers are the only way to properly create diagnostic-quality images and videos from these devices.
In the diagram above, the VGA source is connected directly to a frame grabber-equipped PC with access to the internet. Using any web broadcasting software, the user is able to relay the images and video captured by the frame grabber to his or her audience.
Security System Surveillance Recording and Broadcasting
Today’s security systems and cameras are able to support digital formats as well as high resolutions required for complex security solutions. Of course, as solution is needed to record the outputs from the security system, store it in a digital format, and provide access to the files from remote locations. All of this can be accomplished with VGA frame grabber-based technology, such as the VGA Recorder, which have ample space for recording video files (up to 500GB), are able to directly transmit recordings to a remote FTP location, and give access to the recorded files through a web interface.
The diagram above, borrowed from the Epiphan Systems website, shows how easy it is to hook up a security system’s VGA output to the VGA Recorder. Everything can be set up in minutes, and the VGA Recorder is able to archive hundreds of hours of digital compressed video data to its internal hard drive.
Telemedicine and Remote Guidance
Telemedicine, also known as Remote Guidance, is an expanding field in which doctors are able to, through the internet, diagnose patients and provide advice. Telemedicine has many practical applications but some of the more notable ones are the delivery of expertise to areas in which it is not practical to have a qualified doctor at all times. For example, lets suppose that a player on a sports team gets a knee injury. Through telemedicine, the coach can use a portable ultrasound device like the Logiq Book XP and, with the aid of a frame grabber, relay the images from the Logiq Book directly to a qualified radiologist who can then make a decision on the severety of the injury.
The diagram above shows how any equipment with a VGA output, such as the ultrasound device, can be connected to a frame grabber, and the a computer. The images are then relayed to the qualified radiologist or doctor through the internet or a satellite uplink. If you would like to find out more about the field of remote guidance, then this website is a good start.
Summary
The VGA signal is the most common format used on today’s electronics and computer-based equipment. When this equipment is coupled with a VGA frame grabber, the possibilities are endless. Using a frame grabber, which is a relatively inexpensive device, organizations can not only significantly cut costs, but can also improve their productivity.
Feature comparison table for the world’s best VGA and DVI frame grabbers
July 29, 2008 by admin · 2 Comments
The niche market for VGA and DVI frame grabbers is full of different products, each with its own advantages and disadvantages. Since there are no defined standards in the field of high-resolution frame grabbers, it is often very difficult to choose among the various offerings. Analyzing each frame grabber and then comparing it to others in the industry can be a very tedious task, which is why we’ve compiled a side-by-side comparison table to ease the selection process, making it easy to compare these cutting edge products side by side.
This table was made using specifications supplied via each manufacturer’s website and data sheets. Some manufacturers do not provide complete specifications for their products, in which case “Not specified” is written in the table cell. For actual real-life tests and results, consult the “Reviews” section of this website.
Please note that all specifications supplied by the manufacturer are included in this table, making this the most comprehensive frame grabber comparison on the internet. After the table you will find short descriptions for what each specification means and how it impacts the capture process.
Brand/Product |
EMS Imaging Xtreme RGB |
Epiphan Systems |
Epiphan Systems DVI2USB Duo | Epiphan Systems VGA2USB Pro | Foresight Imaging I-RGB 200 | Ncast DCC 3.1 |
| Product Image |
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| Interface | PCI (internal) | Gigabit Ethernet (external) |
USB 2.0 (external) | USB 1.1 and 2.0 (external) | PCI (internal) | PCI (internal) |
| Board Format | 3/4 Size PCI Card, 105mm x 170mm; PCI Bus Master with scatter/gather DMA providing up to 1GB/sec peak, 500MB/sec sustained |
External device, 7.95″×4.13″×1.38″, 202×105×35 mm; |
External device, 5″ x 3.2″ x 1.2″; 126 mm x 81 mm x 30 mm; USB Bus providing with up to 480 Mbit/s | External device, 80 mm x 54 mm x 23 mm; 3.15″ x 2.125″ x 0.91″; USB Bus providing with up to 480 Mbit/s | 3/4 Size PCI Card; 120+ MB/sec sustained to system memory via PCI bus master; Real-time transfer to VGA memory | Full size PCI card; PCI 33MhZ, 32Bit BUS |
| Connectors | 2 DVI-I Type connectors | Two VGA D type connectors Two Ethernet RJ45 connectors One USB type A connector One 5V DC power supply connector or Power-Over-Ethernet |
DVI dual-link; USB mini B type connetor | VGA D type connector; USB mini B type connector; 5V DC 1.3mm power supply connector | 15 pin D-shell connector (VGA type) | RGB on DB15; DVI-D; S-Video; Composite |
| Input | VGA, DVI (single link) | VGA | DVI (single link and dual link) | VGA | VGA, DVI-A (analog only) | VGA, DVI (single link), composite, S-Video |
| Input Mode Detection | Automatic | Automatic | Automatic | Automatic | Automatic | Automatic |
| EDID Support | Programmable EDID | Programmable EDID | Programmable EDID | Programmable EDID | Not specified | Not specified |
| Video Format | R,G,B plus separate HSYNC and VSYNC signals; R,G,B plus CSYNC signal; R,G,B with Sync-on-Green synchronization. TDMS Single Link | R,G,B plus separate HSYNC and VSYNC signals; R,G,B plus CSYNC signal; R,G,B with Sync-on-Green synchronization. | TMDS Dual Link; HDCP ready | R,G,B plus separate HSYNC and VSYNC signals; R,G,B plus CSYNC signal; R,G,B with Sync-on-Green synchronization. | R,G,B plus separate HSYNC and VSYNC signals | R, G, B plus separate HSYNC and VSYNC signals; TDMS Single Link |
| Maximum Resolution | 2048 x 1536 (VGA) 1920 x 1080 (DVI) | 2048 x 2048 2560 x 1600 (wide) |
2048 x 2048 2560 x 1600 (wide) | 2048 x 2048 | 1600 x 1200 | 1920 x 1200 |
| Update Rate | User defined, typically up to 60 frames per second, limited by available PCI bandwidth. Multi-buffered to eliminate tearing artifacts | Up to 120 frames per second, depending on resolution and amount of change in frames | Up to 52 frames per second, depending on amount of change in frames | Up to 62 frames per second, depending on amount of change in frames | Not specified | YUV mode: 24 60 fps RGB mode: 15 30 fps |
| Capture Rate at 1280 x 1024 | 60 fps | 20-100 fps | 10.0-52 fps | 10.0-62 fps | Not specified | 28-56 fps |
| Color Resolution | 16 bits per pixel, 5:6:5 format; 24 bits per pixel, 8:8:8 format. 16 bits per pixel, YUV(422) Chroma packed YUYV format. | 24 bits per pixel, RGB 8:8:8 format; 16 bits per pixel, RGB 5:6:5 format ; 8 bits per pixel, RGB 3:3:2, 3:2:3, 2:3:3; 8 bits per pixel, 256-grey scale format ; 16 bits per pixel, YUY2(422), UYVY; | 24 bits per pixel, RGB 8:8:8 format; 16 bits per pixel, RGB 5:6:5 format ; 8 bits per pixel, RGB 3:3:2, 3:2:3, 2:3:3; 8 bits per pixel, 256-grey scale format ; 16 bits per pixel, YUY2(422), UYVY; | 24 bits per pixel, RGB 8:8:8 format; 16 bits per pixel, RGB 5:6:5 format ; 8 bits per pixel, RGB 3:3:2, 3:2:3, 2:3:3; 8 bits per pixel, 256-grey scale format ; 16 bits per pixel, YUY2(422), UYVY; | 24 bits per pixel, RGB 8:8:8 format; RGB 8:8:8; RGB 5:5:5, YUV 4:2:2, Y-only | RGB 8:8:8 format; YUV 4:2:0 format |
| Transfer Rate | 330 Megapixels per second | 270 MPixel/s and 532MPixel/s for two consequent frame interlaced grab | 330 Megapixels per second | 270 Megapixels per second | 200 Megapixels per second | 165 Megapixels per second |
| On-board memory | 32MB | 32MB | 32MB | 32MB | 12MB | |
| Multiple devices supported | Up to 32 | Yes, limited by network bandwidth | Limited by number of USB ports present on computer | Limited by number of USB ports present on computer | Not specified | Not specified |
| Operating System | Windows 2000, Windows XP, Windows Vista | Linux (x86, amd64), Windows 2000, Windows XP, Windows Vista (x86, amd64), Mac OS X 10.3.x and up. | Linux (x86, amd64), Windows 2000, Windows XP, Windows Vista (x86, amd64), Mac OS X 10.3.x and up. | Linux (x86, amd64), Windows 2000, Windows XP, Windows Vista (x86, amd64), Mac OS X 10.3.x and up. | Windows XP Professional | Windows 2000, Windows XP, Linux |
| SDK, API | Windows: EMS SDK included. WDM streaming drivers included. | Windows: DirectShow API, Proprietary API (C/C++, VB 6, C#, Delphi) Linux: Video4Linux API, Proprietary API (C/C++) Mac OS X: Quicktime API, Proprietary API (C/C++) | Windows: DirectShow API, Proprietary API (C/C++, VB 6, C#, Delphi) Linux: Video4Linux API, Proprietary API (C/C++) Mac OS X: Quicktime API, Proprietary API (C/C++) | Windows: DirectShow API, Proprietary API (C/C++, VB 6, C#, Delphi) Linux: Video4Linux API, Proprietary API (C/C++) Mac OS X: Quicktime API, Proprietary API (C/C++) | Auto-SYNC automatic configuration software; Example application programs (source code included); Real-time video streaming with AVI file creation; IDEA software development kit; ActiveX controls; Common Vision Blox, Image-Pro Plus, and TWAIN drivers | SDK available: Ncast Screen capture software application, Ncast Control Program for settings |
| Power Requirements | Max current at +3.3V – 1A Max current at +5V – 1A Max power – 8 Watts | 5V DC external adapter or Power-Over-Ethernet | 5V DC external adapter | 5V DC external adapter | Not specified | Input RGB analog 1600×1200 (capture set to 18fps): 3.3V @ 1.20A = 3.96W; 5V @ 0.55A = 2.75W; Total= 6.71W typical |
| Operating Temperature | 0 to 35 ?C | Not specified | Not specified | Not specified | Not specified | 0 to 35 ?C |
| Storage Temperature | -20 to 70 ?C | Not specified | Not specified | Not specified | Not specified | Not Specified |
| Relative Humidity | 5% to 90% non-condensing | Not specified | Not specified | Not specified | Not specified | 5% to 90% non-condensing |
| Other Features / Specifications | Update rates when used with the EMS Vigilant-X graphics card are: 1 channel at 1280 x 1024 = 75Hz. 1 channel at 1024 x 768 = 75Hz. | LEDs to indicate operational status (power, source, capturing) | LEDs to indicate operational status (power, source, capturing) | LEDs to indicate operational status (power, source, capturing) | Pixel jitter: 0.5 ns S/N ratio: 47 dB Dedicated trigger input Camera power: +12 V DC @ 1.0 A Camera integration Dedicated high current digital output | Simultaneous capture of two synchronized input streams; Picture-in-Picture capability |
| Common Applications | Capturing VGA and DVI signals using a stationary source | Capturing a VGA signal over a distance; | Capturing high-resolution imagery from dual-link DVI signals. High speed and high precision military, medical, and industrial applications. | Capturing ultrasound, radar and other industrial diagnostic-quality images. Broadcasting VGA output to web. | Capturing VGA and DVI signals using a stationary source. Monitor, display testing. Supports camera integration. | Capturing camera output, archiving HD video. |
| Price | Not specified | $1 600.00 | $2 000.00 | $2 000.00 | Not specified | $ 1 995.00 |
This table was made using specifications supplied via each manufacturer’s website and data sheets. Some manufacturers do not provide complete specifications for their products, in which case “Not specified” is written in the table cell. For actual real-life tests and results, consult the “Reviews” section of this website.
| Brand/Product | PixelSmart VGA-Master | Unigraf UFG-03A Hidef |
| Product Image |
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| Interface | PCI (internal) | PCI (internal) |
| Board Format | Full size PCI card; 32 bit 33 MHZ 5 Volt BUS | 3/4 Size PCI card; 175mm length; PCI bus master; bursts up to 133 MBytes/sec; Compatible with both 5 V and 3.3 V bus logic voltages |
| Connectors | DB15 VGA | RGB on DB15; DVI-D; optional composite video |
| Input | VGA | VGA, DVI (single-link) |
| Input Mode Detection | Not specified | Automatic |
| EDID Support | Not specified | Not specified |
| Video Format | R, G, B plus separate HSYNC and VSYNC signals | R,G,B plus separate HSYNC and VSYNC signals; R,G,B plus CSYNC signal; R,G,B with Sync-on-Green synchronization. |
| Maximum Resolution | 1280 x 1024 | 1600 x 1200 |
| Update Rate | Not specified | Not specified; Progressive and interlaced scan modes. |
| Capture Rate at 1280 x 1024 | Not specified | Not specified |
| Color Resolution | Not specified | 16, 24, 32 bits per pixel |
| Transfer Rate | Not specified | 133 Megabytes per second (~300 MP/s) |
| On-board memory | Not Specified | |
| Multiple devices supported | Up to 4 | Up to 10 |
| Operating System | DOS, Windows 98, Windows 2000, Windows NT, Windows XP | Windows 2000, Windows XP, Linux |
| SDK, API | Victor SDK by Catenary Systems; ImageJ processing software. | Video for Windows, UFG-03 Extended Driver Interface, SDK with examples, DLL library, C++, Visual Basic, LabView code included |
| Power Requirements | Not specified | 7.5 watts maximum |
| Operating Temperature | Not specified | Not specified |
| Storage Temperature | Not specified | Not specified |
| Relative Humidity | Not specified | Not specified |
| Other Features / Specifications | None | Picture-in-Picture mode allows for up to 10 capture images displayed on one screen; Hardware image scaling from half of imput image size to 1600 x 1200 |
| Common Applications | Presentation recording, low-quality image capture | Webcasting, testing and measurement (LabView) |
| Price | $349.00 | Not specified |
*Manufacturers specification sheets were used to compose the table above. In cases where the manufacturer did not indicate a specification, not specified is written in the table cell.
Analysis
Interface
All manufacturers except for Epiphan Systems, which makes external USB-based devices, produce internal PCI cards.
Input
Frame grabbers from Epiphan Systems and PixelSmart only have one input for a single VGA or DVI stream. However, Epiphan Systems DVI2USB Duo is the only frame grabber on the market that is able to capture dual link DVI signals with a maximum resolution of 2048×2048. Ncasts DCC 3.1 gives the user the most choice in terms of signal inputs as it has on-board VGA, DVI, composite, and S-Video inputs.
Capture Rate
Out of the two manufacturers that specified capture rates in their specification tables, Epiphan Systems has the highest possible capture rate at 62 frames per second, while Ncast has a higher lowest frame rate at 1280 x 1024. Capture rate depends highly on the nature of the image that is being captured. The user will notice lower capture rates in applications where there is a lot of movement in the VGA or DVI source.
Color Resolution
Compared to other manufacturers, Epiphan Systems VGA2USB and DVI2USB have the widest range of support for different video formats, whereas Unigrafs UFG-03A is the only frame grabber with support for a color resolution of 32 bits per pixel.
Transfer Rate
The maximum transfer rate determines how much data can be moved between the frame grabber and the computer. While it doesnt directly affect the picture quality, a higher transfer rate means that the frame grabber can handle more pixel changes from frame to frame.
Multiple Devices Supported
Many times, the user needs to record output from multiple sources onto one device simultaneously. Basically, this number indicates the maximum number of devices all functioning at the same time, while connected to a single computer.
Operating System
All manufacturers have Windows XP support. Epiphan Systems is the only manufacturer to support MAC OS X while PixelSmart is the only company to have support for the ancient command line-based DOS and Windows 98 operating systems. Epiphan Systems, Ncast, and Unigraf are the only companies to support Linux.
SDK/API
All manufacturers provide the user with an SDK and sample code. Epiphan Systems and Unigraf are the only two companies which produce Video for Windows capable frame grabbers which have the capability to appear as high-resolution cameras in Windows.
Price
All high-resolution and high quality frame grabbers are generally priced around $2 000 USD. PixelSmarts VGA-Master is priced at only $349 because it is not capable of grabbing high resolution signals, meaning that the picture quality will be poor compared to the other frame grabbers in this review.
*Note
Be wary of manufacturers that omit important specifications such as capture rate in their specification sheets. Specifications are usually not included if the product is unable to achieve steady performance.
