May 1, 2005 12:00 PM, By Bennett Liles
Versatile boxes process video for large-screen display.
Before DVDs and laptop computers, the topic of scalers lingered in an obscure corner of the AV industry, and the word was more often associated with mountain climbing or model airplanes. But the explosion of portable presentation technology, video projection displays, and inexpensive, high-quality digital storage has thrust scaling technology to center stage. Scalers are everywhere now. They are built into data projectors and other devices and are marketed on their own with a wide variety of designs and features.
Key Digital HD Leeza
As with any AV equipment, smart selection depends on a thoughtful analysis of the specific application in which the scaler will be used. The choice among scalers can be confusing — there's a wide range of feature sets and supported formats. It is best at the outset to take a step back and consider what a scaler really is and what it does. In this article, I will examine a representative group of devices that accept video and computer sources and offer scaling as a primary feature of their operation. I will focus on scalers that are designed to push images to indoor projector screens, HDTVs, and plasma and LCD screens. (I will save for a later discussion similar products that incorporate scaling with other processing techniques intended for large outdoor displays and videowalls.)
Video and computer displays were originally designed to be seen by a small audience at a fairly close range. As the need for larger video and computer displays has grown, scaling technology has answered the call to maintain picture quality while dramatically increasing the image size. This job can be accomplished through simple line doubling or quadrupling by an upconverter. But a scaler's processing power is needed to control output resolution and aspect ratio, to compensate for motion artifacts, to de-interlace and integrate various video formats with computer inputs, and to translate film frame rates to video rates.
When an interlaced scanning beam scans rapidly moving images, the moving edges are going to be displayed in slightly different places in successive image scans. This will produce sawtooth edges called “jaggies.” Scalers use two methods of converting interlaced video input to progressive-scan output. For still images, static mesh processing is used to merge the odd and even fields of each frame into one fairly sharp, crisp image. To deal with jaggies from moving parts of the image, a technique called vertical temporal (VT) processing is employed. This replaces the jagged lines with a new, averaged line that the scaler creates between the places where they appear on odd and even fields of each video frame. Most modern scalers combine static mesh and vertical temporal processing and apply each appropriately, according to the amount of motion in the video image.
Analog Way V-Scale
FILM TO VIDEO
With any source originating on film, conversion is necessary to handle the difference between 24fps film and 30-frame (60-field) video. For the smoothest motion, the first film frame is scanned to make three video fields. The next frame makes two video fields, the next after that makes three again, and so on. The process is known as 3:2 pulldown. Many scalers have the ability to sense this same-frame/different-frame pattern and automatically apply a process of “inverse 3:2 pulldown” or “adaptive frame mode” to handle this film-to-NTSC video frame sequence.
Film has always required aspect ratio conversion to be displayed via video, but the parameter of aspect ratio has achieved new prominence with the coming of HDTV. Many scalers have the ability to adapt 4:3 NTSC video to widescreen ratios and to display original widescreen 1.66:1, 1.85:1, and 2.35:1 film formats at SDTV's 4:3 or HDTV's 16:9 aspect ratio. The conversion to 4:3 is often accomplished by letterboxing, the insertion of horizontal black bands above and below the frame. Going the other way, a 4:3 image displayed on a 16:9 screen has vertical black bars inserted on each side. Anamorphic scaling is another method of displaying a 4:3 original image on widescreen displays by compressing the image vertically to fit the widescreen frame. Most consumer widescreen TVs have this scanning feature built in.
Another distinctive feature of modern scalers is their ability to store various settings and associate these with specific inputs, so that when a source is selected, the various technical parameters don't have to be set up again. Auto-scanning is also available for automatic detection of and adjustment for the input signal parameters. Some models also feature RS-232, infrared, and IP control from remote locations via LAN/WAN.
Universal scalers can translate HDTV, RGB, component video, S-Video, composite video, and SDI (Serial Digital Interface) into a single output format. Video scalers handle only the various video input formats and provide multiple scaled outputs. Among these outputs are RGB, video, plasma, and HDTV formats. RGB scalers input high-resolution computer signals and convert them to video images of various aspect ratios.
One of the central components of a scaler is the scaling chip, but keep in mind that the scaling operation is a relatively minor part of the conversion process that most modern scalers accomplish. The quality of the output signal is affected most in the decoding and de-interlacing operations. The scaling process, in comparison, is relatively simple and has less effect on output quality.
Most scalers available today combine a number of other operations with their core features. Many incorporate manual source switching among a number of video and computer inputs, and some offer remote control via IP, infrared, and RS-232. Keeping in mind the basic question of the intended application, let's take a look at what is available in today's eclectic world of modern scalers.
Analog Way, based in Paris with offices in New York and Singapore, has just introduced the cost-effective V-Scale video scaler. The V-Scale accepts composite and S-Video sources intended for display on high-resolution LCD and plasma screens and via video projectors. Featuring multiple outputs and display resolutions up to 1400×1050, the unit automatically displays full-frame memory in the event that input sync is lost. It also automatically switches to a user-defined source when the present input signal is lost. The product offers complete RS-232 remote control.
The DIDO high-resolution scaler from Aurora Multimedia is a very versatile unit. It features composite, S-Video, YPbPr, RGBHV, and DVI inputs. Output resolutions include 1080i, 720p, 480i, 480p, VGA, SVGA, XGA, SXGA, UXGA, and WUXGA. Audio switching is included. An especially interesting capability is its multi-image rotation with quad-split, split-screen, and translucent overlay. An internal event scheduler uses a realtime clock to control single or multiple units connected by RS-485 bus. RS-232 and handheld IR remote enable control from a distance. The product retails for less than $4,000.
Communications Specialties is a Long Island-based company that specializes in computer-video technology and fiber-optic transmission. Among the company's products is its line of Deuce video scalers. All of the Deuce scalers accept NTSC and PAL video sources. The Deuce MC, with six motion compensation settings, includes composite video input on female RCA connectors, S-Video on mini-DIN F, and component on female RCA connectors. The HD-15F output connector can be configured for RBHV, RGBS, or YCC through a rear-panel switch. Output resolutions include 800×600, 852×480 (16:9), and 1034×768. It also has line-doubling and line-quadrupling functions. One interesting feature of the Deuce MC is its six user-selectable motion compensation settings — including static mesh, vertical temporal, and adaptive frame (inverse 3:2 pulldown) — which can be applied individually or in combination. Automatic modes analyze the input signal and apply the appropriate motion-control methods. The unit also includes a three-pin Phoenix connector on the rear panel for RS-232 control. Output refresh rates are 59.95Hz for NTSC and 50Hz for PAL. The Deuce HD model outputs a variety of progressive-scan formats, and the Deuce Pro has 10 outputs, offers three selectable refresh rates, and supports four aspect ratios. The Deuce SDQ affords economical operation with scaling to three selectable resolutions. The Deuce line ranges in price from about $800 to $1,500.
Crestron, of Rockleigh, N.J., markets a variety of products in the AV field. Among those with scaler functions is the C2N-DVP4DI video processor. This unit features multi-window displays: Up to four scalable windows may be simultaneously displayed among up to 12 composite, S-Video, or component video inputs and four RGB/computer or DVI-I sources, using the unit's 12×4 switcher. All this goes to a single DVI-I output that can be formatted as 4:3 or 16:9 in resolutions up to 1600×1200 RGB and 1280×1024 DVI. Automatic source identification assigns the optimal processing algorithm for all sources, including 3:2 NTSC and 2:2 PAL pulldown. The C2N-DVP4DI includes a touchpanel interface and Ethernet control. MSRP is $15,000.
DVDO, located in Campbell, Calif., offers the iScan HD+, a high-resolution video scaling processor and AV switcher. The unit differs from the iScan HD only in that it is HDCP-compliant, meaning that it employs digital content protection on the DVI connections. HDCP (High-bandwidth Digital Content Protection, approved by the FCC late last year) is a feature to prevent unauthorized digital copying. Among the model's features are 3:2 NTSC pulldown, 2:2 PAL pulldown, 480i and 480p inputs through composite and S-Video connections, 720p and 1080i inputs, 12-bit digital-to-analog video conversion, input and output aspect ratio control, four audio inputs and two audio outputs, full-frame time base correction, and AutoVFR intelligent component video inputs with automatic video format routing. The iSCAN HD+ retails for about $1,500.
Lumagen Vision HDP
DWIN Electronics of Burbank, Calif., offers the TranScanner 3 system controller and video formatter. The product accepts up to 10 different input video signals and produces a DVI-HDCP signal for DLP/LCD projectors and plasma displays. HDTV/DTV output resolutions include 480p, 720p, and 1080i. Computer outputs, including VGA, SVGA, SGA, and SXGA, are compatible with 4:3 and 16:9 aspect ratios. Plasma screen resolutions are 859×480, 1366×768 and 1024×1024. The unit can input two DVI-HDCP signals, two RGB, two component YPbPr, two S-Video, and two composite video signals. The TranScanner 3 features 3:2 NTSC and 2:2 PAL pulldown and both IR and RS-232 remote control. Enhancements include adaptive film mode processing and signal dynamic range expansion. Up to 20 video source memories can store individually tailored setup parameters. The system lists for around $3,500.
Extron Electronics of Anaheim, Calif., is a longtime leader in the scaling realm. The company markets its DVS 406 digital video scaler among a vast range of other video, AV control, and presentation products. This model comes in two variants: the DVS 406A and the DVS 406AD. Both include audio switching with the video, and the DVS 406AD adds the SDI input. The DVS 406 features 3:2 NTSC film pulldown and 2:2 PAL pulldown. True Rate Scaling Technology adds fields to film-originated video to equalize frame rates in order to avoid a phenomenon called “judder,” a jittering effect that often occurs during film frame-rate translation. The unit also applies an automatic motion compensation process that Extron calls Dynamic Motion Interpolation (DMI). The DVS 406 handles inputs from RGBHV, SDI (optional), composite, and S-Video. The output is RGBHV, RGBS, and RGsB in scaled resolutions from 640×480 to 1360×1024, 720p, 1080p, and 1080i. The six balanced/unbalanced audio sources connect on rear terminals. The audio input levels can be adjusted to avoid noticeable level changes upon switching. The unit may be controlled remotely through RS-232 and hardwired IR or with an optional IR remote. Also included is the interesting ability to key graphical characters over video input. This versatile product, for all its features, is amazingly easy to set up and operate. It lists for about $4,500.
Focus Enhancements of Campbell, Calif., offers the CS-1 and CS-2 video processors with multiple scaling features. The models differ in that the CS-1 has DVI in and out and is not HDCP-compliant, while the CS-2 has DVI and DVI-HDCP in and out. The units input NTSC, PAL, and SECAM sources, as well as composite, component, and S-Video. They include the VGA pass-through. Aspect ratios at the inputs are 4:3, 16:9, 4:3 letterbox, and 16:9 letterbox, while the output provides 4:3, 16:9, and anamorphic lens support. The DVI input can accept resolutions from 640×480 to 1280×1024, and user-adjusted input parameters are auto-saved. An ambient light sensor automatically adjusts the brightness of the 32-character LCD display. 3:2 pulldown is also available. The CS-1 lists for approximately $1,700, and the CS-2 retails for about $2,100.
FSR of West Paterson, N.J., markets the Compass presentation switcher, which incorporates scaling functions to process composite, component, S-Video, and computer RGB signals up to 1600×1200. The Compass accepts these signals on any of its seven universal inputs on DB-15 connectors. An eighth video source can be a corporate logo. All input parameters are individually programmable, and the unit features RS-232 remote control. Audio switching is included, and dissolves, wipes, and other transition effects may be programmed. Output resolution is selectable from 640×480 to 1365×1024. Calibration of display devices may be made with internally generated test patterns. The Compass lists for approximately $6,000.
KeyDigital Systems of Riverdale, N.Y., offers among its video processing products the KD-HD1080P HD Leeza. The unit offers HDTV and SDTV scaling in 480i, 480p, 576i, 576p, 720p, 1080i/540p, and 1080p for plasma, LCOS, D-ILA, DLP, LCD, and CRT projectors as well as HDTV and SDTV monitors. Digital inputs include DVI-HDCP and SDI. The unit also features analog inputs including component, RGBHV, S-Video, and composite. Outputs are DVI and RGBHV in resolutions from 640×480 to 1920×1080. The HD Leeza can accommodate any new digital equipment addition without leaving the analog world behind. Control methods include Crestron-compatible RS-232 and IR remote with onscreen setup display. The product retails for about $4,000.
Kramer Electronics, based in Israel, has introduced its Proscale digital scaler/switchers. These include the VP-725DS video-only and VP-725DSA video and audio units. Each handles five different formats along with 18 input sources, including composite, S-Video, component (YUV or RGB), computer graphics video on a 15-pin HD connector, and DVI (2 DVI-D). Featuring two switching modes, the product can switch any input in a group to that group's output. A scaling function switches any video source into the unit's 15-pin HD, DVI-D, and five BNC connectors for RGBHV output at a multitude of selectable resolutions. The unit also features picture-in-picture and fade-through-black, audio breakaway, and text overlay. Control options include IR remote, RS-232, and Ethernet. The VP-725DS lists for $2,995 and the VP-725DSA retails for $3,175.
Lumagen of Beaverton, Ore., markets several video processors with scaling functions. Among these is the Vision HDP, which features eight inputs: two composite, two S-Video, two SD/HD component, and two DVI inputs with HDCP copy protection. Two more SDI inputs may be added as an option. Outputs include DVI-HDCP, and resolutions range from 480p to 1080p. Remote control is possible through IR or RS-232. Output aspect ratio is selectable from 1.33 to 2.35 in steps of 0.01, and size/position is programmable in pixel increments. Also 3:2, 3:3, and 2:2 film pulldown is frame-reconstructed for SD and HD sources. Software updates are available on the company website, and the unit lists for about $1,500.
Pixel Magic Systems of Hong Kong markets the Crystalio VPS-2300 scaler and video processor as a do-it-all product with a wide range of input and output formats. Crystalio uses a DCDi (Directional Correlational De-interlacing) algorithm to eliminate jaggies from rapidly moving portions of the displayed image. The VPS-2300 employs inverse 3:2 pulldown for film-originated NTSC content, 2:2 pulldown for PAL, and adaptive noise reduction for moving images. The product includes an HDTV digital input and three SDI inputs, as well as component, RGB, composite, and S-Video inputs. Outputs include DVI (Digital Video Interface), RGBHV, and component video on BNC connectors as YPbPr and YPbCr. Control options include RS-232 via DB9 and direct IP control via an RJ-45 connector on the rear panel. A USB connector is also available for upgrades. Thorough user-selectable setup control is available by following menus using four up/down and left/right buttons, which also enable selectable aspect ratios, hue, contrast, color, brightness, sharpness, and other manually adjustable enhancements. The unit also offers a huge range of output display resolutions, from 800×600 to 1920×1080. Display resolution may be selected through a library of display makes and models. Though it has a slight learning curve, the VPS-2300 is an extremely versatile product and retails for around $3,500.
Runco International of Hayward, Calif., offers its line of virtual high-definition processors, including the DHD digital controller with Vivix II digital video processing technology. The product includes 3:2 and 2:2 film pulldown. The VirtualWide feature is designed for conversion of 4:3 images to 16:9 displays with maximum picture quality. Inputs include one composite, two S-Video, one component (480i or 576i), two RGBHV/component HD, and two DVI digital with HDCP. The unit can handle aspect ratios including anamorphic, letterbox, VirtualWide, and 4:3 (on either 16:9 or 4:3 displays). Besides the front-panel controls, control options include RS-232, a nine-pin connector, discrete infrared remote, RJ-11 connector, and of course, the front-panel controls. All of these features are packed into a small chassis that weighs only 13lbs.
Scancom of Margate, England, offers the AVT-3800 ImageMax Plus scaler as a low-cost solution. This is appropriate if your scaling needs are fairly straightforward and the input sources are analog. Video from DVD players, VCRs, camcorders, video games, and satellite receivers can be scaled for viewing on RGBHV or component display inputs. Aspect ratio selection includes 4:3 and 16:9, and the unit also provides 3:2 NTSC film pulldown. RGB output resolutions range from 640×480 to 1280×1024, and HDTV outputs include 480p (576p in PAL), 720p, and 1080i. IR remote control is included, with onscreen display. The product can input composite, component, and S-Video sources. Operators can control contrast, brightness, hue, and saturation. At around $650, this unit will fit the bill for analog video scaling.
The OptiScale from Silicon Optix of San Jose, Calif., features digital and analog signal switching on a simple-to-operate panel. Input capabilities include composite, S-Video, and component, with HD in 720p and 1080i. With SECAM, PAL-M, PAL-N, and NTSC standards compatibility, you can take it anywhere. Output resolutions include 720p, VGA, SVGA, XGA, SXGA, and SXGA+. It serves plasma displays up to 1366×768. Multilingual onscreen and front-panel menus complement RS-232, RS-422, RS-485, and IR control modes. Picture controls offer contrast, brightness, hue, gamma, zooming, panning, and aspect ratio conversion. The OptiScale lists for just less than $2,000.
TV One, located in Erlanger, Ky., markets the C2-4100 as a high-performance PC-HDTV video scaler, but as is the case with many products billed as scalers, the unit features much more functionality. The C2-4100 inputs and outputs YPbPr, RGBHV, RGsB, and RGBS up to 2048×2048 and handles all HDTV resolutions. Some of the more interesting professional features include picture-in-picture between any two sources and a preview output for use during live events. One handy feature is a nonvolatile memory for the settings of each input. Remote control is available through RS-232 and, as options, IR and Ethernet. Audio switching is included and can be done in audio-follow or audio breakaway modes. The C2-4100 retails for around $3,000.
Zinwell Digital of Walnut, Calif., offers the Brite-View DVI de-interlacer/scaler as a versatile little product, especially in view of its $600 price. The Brite-View inputs composite, component (YCbCr), and S-Video in all NTSC and PAL formats, and it provides RGB output in resolutions of 640×480, 800×600, 1024×768, and 1280×1024. Component output (YPbPr) is available in 480p, 720p, and 1080i. These RGB and component outputs are selected via a hardware switch. The latest model, the Brite-View DVI, includes a DVI output. Also featured is automatic 3:2 NTSC and 2:2 PAL film pulldown. Parameters such as contrast, brightness, color, tint, sharpness, resolution, display format, and language are also adjustable. IR remote control is available.
The scaler market is dense and diverse. The models listed here are but a few of the representative devices. It makes sense to examine carefully the specific application — along with possible future uses — before deciding on the exact make and model to suit the task.
For More Information
Pixel Magic Systems