"D" Is for Digital: Video Digitizers and Nonlinear Editing

by William Ronat
July 1997

Why should you care about video digitizers? Because the way that we view, shoot, record, edit and deliver video is changing faster than you can say information superhighway.

Just look around. The new DV format is here, and the D stands for digital. Satellites and fiber-optic cable deliver information digitally. Home digital-video teleconferencing is just around the corner. Leaders in the computer industry have decided for all of us that the World Wide Web is the place to be. How do you supply video for these hip virtual destinations? By digitizing it.

In this article, we'll look at the types of products that can give you what it takes to move into the digital world. If you are new to computers, you may want to get your feet wet first by capturing still images from video with an inexpensive frame grabber. A serious hobbyist might want to capture moving video on a computer with a motion video digitizer or with a complete turnkey nonlinear edit system. Once you've got the video on the hard drive, you'll need some way to make editing decisions and carry them out; this is where nonlinear editing software enters the picture. These are the types of products we'll be looking at: still-capture devices, motion-capture boards, nonlinear-editing systems and software.

Before we get into the products themselves, however, let's take a brief moment to bring some of the digitally uninitiated in our audience up to speed. If you're a hot-shot digital whiz kid who already understands the subject right down to the chip level, then feel free to skip ahead to the next section. If not, don't fret; the following introduction to the subject should clear the way.

Ones and Zeros
How does it all work? What do video digitizers do, exactly? Here's the short answer: they convert the continuously varying voltage of an analog video signal into numerical information so you can store it on a hard drive.

Confusing? Perhaps. The important factor to remember is this: what most people call video--analog video--is completely different from its digital sibling. To store video on a computer's hard drive, you must convert the analog signal to digital information (ones and zeros). Similarly, if you want to transfer the images on your computer screen onto analog videotape--VHS, for example--you have to convert them from digital to analog.

Both of these jobs--converting analog to digital and digital to analog --are the basic operations performed by still- and motion-video digitizers. It's a rather difficult task for the computer, converting analog video to a string of numbers. A good way to get the feel of what it means to convert analog video to digital information is to look at a digitizer that only produces still images. As video flies by at 30 frames per second, a still-capture board grabs one of these frames and turns it into a picture that you can view or manipulate on your computer. Sometimes, the computer needs a few seconds to render the still frame on your screen. Imagine doing the same thing to each frame 30 times a second, and you can see why motion-video digitizers are truly a miracle of modern technology.

Also of particular concern is the large amount of data that digital video represents. To record raw video--full-frame, full-color, full-motion video--you'd need a hard drive that could record about 27MB of data every second. Most drives can't even keep up with a moderate 5MB-per-second data flow, much less find room to store a short video clip that consumes more than 1GB per minute. The solution: use a codec (compression/decompression scheme), such as MPEG or MJPEG (see sidebar). Most video capture cards include on-board hardware to compress the incoming video so the hard drive can keep up with it. The most common type of codec used to compress full-screen, full-color, full-motion video is MJPEG, or Motion-JPEG.

The three most important performance characteristics to look for in a video capture device are its maximum bit depth, its maximum number of vertical and horizontal pixels, and its maximum capture rate. Bit depth refers to the amount of color information assigned to each pixel. The number of vertical and horizontal pixels affect the device's capture resolution. And the capture rate affects the overall quality of the video. A good trio of benchmarks to consider are 24-bit color, 640x480-pixel capture resolution and a capture rate of at least 1MB/second. These guidelines are for those of you who need a good bottom-line minimum figure for what's necessary to output your productions to videotape. If your final target is the Web or CD-ROM multimedia, then you can (and should) work with slower capture rates and fewer pixels in order to keep the size of your final productions down in the megabyte range, instead of the gigabyte range.

When looking at video digitizers, you may notice that the price goes up as you add speed (megabytes per second) and visual quality (bit depth and resolution). The best bet is to try to see equipment in action before you buy. Checking Usenet discussions, or Videomaker's Web forums (http://www.videomaker.com/forument.htm) can also be helpful.

Still-Image Capture
What use might you find for a still capture board? You could snap some pictures of yourself and your kids and e-mail them off to relatives and friends. You could capture pictures from raw, unedited video and create a storyboard to help you make editing decisions. You could use the images in printed literature-- perhaps a marketing piece about your company to sell your video services to clients. You could use a still image from your video as a background for titles. Or you might use the digitized images on your Web site or in a PowerPoint presentation.

One of the most popular still-image capture devices is Snappy from Play, Inc. For $199, this device plugs into your computer's parallel port and captures still images from any NTSC video source. Bundled software includes Adobe PhotoDeluxe, Kai's Power Goo SE and Gryphon Morph. Snappy works with Windows 3.1, 95 and NT. Maximum capture resolution is 1500x1125 and maximum bit depth is 24.

The AIGotcha! from AITech is a similar product that works with Windows 3.1/95. At a suggested retail price of $169, it delivers a maximum bit depth of 24 and maximum capture resolution of 1600x1200. One of its main selling points is the presence of an S-video connector, which is missing from the Snappy.

Another contender in this category is the VideoShot from VideoLabs, which captures 640x480-pixels with a maximum bit depth of 24. It sells for $199.

Movin' On Up
There has been a lot of commotion in the motion-video digitizer category in the past year. Current trends include boards that digitize both video and audio, and low-priced units that almost anyone can afford. (Note: if your video board doesn't capture audio, you'll need to purchase a sound card to fulfill this duty.)

For Web and multimedia developers, there's the Intel Smart Video Recorder III, a motion-video capture card that supports resolutions up to 640x480 with 24-bit color. At $199, the Intel Smart Video Recorder III includes Asymetrix's Digital Video Producer and Web Publisher software packages.

Another good choice for Web and multimedia developers who want to work with MPEG is Data Translation's Broadway 2.0 ($995), a board that has the ability to capture and compress moving images and audio in the MPEG-1 codec "on the fly," as the video is playing. The Broadway captures 24-bit color at a maximum resolution of 352x240 pixels.

Matrox has recently introduced the Rainbow Runner Studio, which at $249 provides an inexpensive solution for those who want full-color, full-screen, full-motion digital video. A companion card for the Matrox Mystique ($159) graphics accelerator, the Rainbow Runner Studio provides a low-cost nonlinear editing solution for home users. It can capture video from any analog source, such as a VCR, camera or laser disc. Rainbow Runner Studio uses hardware Motion-JPEG compression, and comes bundled with Ulead's MediaStudio video editing software, iPhoto Express for image editing, a software MPEG converter (for producing videos for use on CD or the Internet) and VDOnet's VDOPhone for video conferencing.

Fast Electronics offers the AV Master ($899), an MJPEG board that captures both audio and video. Maximum resolution is 640x480, and the color is 24-bit. Included with the board is Ulead's MediaStudio Pro software, as well as Fast's own AVI Warp, FastCap and MediaCache utilities.

The Bravado 1000 ($699) from Truevision is available for the PC or Macintosh platforms. The Bravado 1000 uses Motion-JPEG compression and allows you to capture 640x480-pixel, 24-bit color video directly to hard disk. The full retail version of Adobe Premiere 4.2 (discussed later) is included.

Another popular maker of video capture boards is miro Computer Products. Their two most current products are the miroVideo DC10 ($399) and the miroVideo DC30 ($999). The DC10 has a maximum capture resolution of 340x480 and a maximum MJPEG compression of 6:1. The DC30 increases the maximum resolution to 704x480 and the maximum data rate to 6MB/second. The DC30 board captures incoming audio as well as video.

These are but a few of the players in the digitizer and nonlinear editing hardware market. Many more are listed in the buyer's guide accompanying this article.

Software Choices
Having gone to all of the trouble of getting your video onto your hard drive, what will you do with all those zeros and ones? Edit them, of course.

For $79, the Digital Video Producer from Asymetrix puts video editing capabilities in the hands of any Windows 3.1, 95 or NT user. The timeline uses two video tracks, and automatically applies transitions to overlapping video tracks. The program includes 15 different types of transitions, including fades, dissolves and wipes.

MediaStudio Pro 5.0 from Ulead Systems ($595) delivers 32-bit video editing for Windows 95 and NT. In Video Editor, you arrange video, animation, audio, image and graphics files in many popular file formats on up to 101 video and audio tracks. You can overlay and animate text, images and video with 3D moving paths, or map overlays onto 3D spheres and cylinders. Also included are F/X Studio, a gallery of video filters and transition effects, Multimedia Converter, Image Editor, Audio Editor, Morph Editor, Album and other modules for multimedia material.

Star Media Systems offers two Windows-based products: Video Action Pro ($499) and Video Action NT ($999). Each is a comprehensive 32-bit digital-editing software package with transitions, filters, titling, animation, keying, morphing, warping and sound.

Adobe's Premiere for Macintosh or Windows is one of the most popular and flexible nonlinear software packages available. Premiere supports both Apple's QuickTime and Microsoft's Video for Windows formats, so it can work with a wide range of hardware and software products. Version 4.2 ($795) includes features that optimize movies for smooth, low-data-rate playback on CD-ROM and the Web. The graphical interface displays video clips in "filmstrip style," with variable zoom-in and single-frame viewing.

One of the main advantages of Premiere is the wide range of plug-in software products available from third-party manufacturers. Products like Artel Software's Boris Effects Pro or Videonics' Video ToolKit can add functionality to your existing Premiere system without requiring a whole new nonlinear editing software package.

Speed Razor Mach 3.5 ($1495) is a higher-end editing and compositing software package from in:sync. Features include many items that you wouldn't need for most simple hobbyist setups--features like D1 quality output (a very high-quality digital-video format) and full-field rendering with no project-length limits, flexible effect-compositing tools and real-time audio mixing (from six to 20 tracks).

Speed Razor offers a character generator, an infinite number of video tracks, an infinite number of audio tracks, and support for time code and RS-422 deck control. The software works only under Windows NT.

Digital Is as Digital Does
There's no doubt about it: the world is going digital. This is a good thing. Analog video can deteriorate rapidly when it is played back and recorded, played back and recorded, played back and recorded. Digital video remains pristine through repeated manipulations, duplications and edits.

And you can use digital video on computers, CD ROMs or DVDs, and on the Web. Five years ago, only a few visionaries would have thought these things possible. Imagine what the next five years might bring.

Whatever it is, you can bet it will be digital.

Videomaker contributing editor William Ronat owns a video production company.

Sidebar

Glossary of Terms

Analog Video: Video information in the form of a continuously varying voltage. Currently, it's the standard way of encoding a video signal for transmission over the airwaves, through cable systems, or on videotape or laser disc. In the not-too-distant future, however, digital video will become the new standard.
Codec: Compression/decompression scheme used to reduce the size and data rate of digital video files. Common codecs include MPEG and MJPEG.
Digital Video: A way of encoding a video signal by transforming its analog waveform into a series of ones and zeros (digital information).
Frame Grabber: A type of video digitizer that captures only a single frame of video. You can then view, manipulate and store this image on the computer.
Motion Video Digitizer: A type of video digitizer that captures a moving stream of video for viewing, manipulation and storage on a computer.
Motion JPEG (Joint Photographic Experts Group) or MJPEG: A type of digital video codec that's commonly found in motion video digitizers. MJPEG is derived from JPEG, the type of still-image compression that's named for the Joint Photographic Experts Group.
MPEG (Moving Picture Experts Group): A popular type of digital video and audio codec. Web videos, CD-ROMs, DVDs and digital satellite services currently use various forms of MPEG.
Nonlinear Editing: The process of creating a video program from digital video stored on a hard drive. Also called random-access editing, nonlinear gets its name from the fact that you never have to rewind or fast forward a videotape to access any particular "clip" or section of the video.
Video Digitizer: A computer peripheral that transforms an analog video signal into a series of ones and zeros.

Rate This Article

Rating: 1 (Poor) - 5 (Excellent)

	1	2	3	4	5
How would you rate the author of this article?
How Would you rate the overall value of this article?
How would you rate the graphics?
How would you rate this article's method (i.e interview, tutorial, narrative) for explaining this topic?
How would you rate the depth and length of the article