Everything You Wanted to Know About Digital Video Editing at the Desktop

Jan Ozer

EMedia Professional, March 1997
Copyright © Online Inc.

----------------------------------------------------------------

Desktop Digital Video Editing: In the Beginning, VidCap and VidEdit
In the beginning, there were VidCap and VidEdit, the capture and editing tools supplied by Microsoft with its original Video for Windows release in 1991. While these programs lack the advanced features of second- and third-generation video editors, they excelled at the simple tasks for which they were designed.

VidEdit is still the standard for compression performance by which other programs are judged. Due to Microsoft's poorly documented application programming interfaces (API's), most video editors had or still have problems matching VidEdit's compressed video quality and ability to produce files that play back smoothly from CD-ROM.

In fact, for a surprising number of simple functions like clipping unwanted frames from a captured file, re-interleaving audio and video files, computing an optimal palette, and compressing to final output, VidEdit is still the program of choice. If you've got a copy, archive the disk for eternity, because you'll always want to be able to reinstall it. If you don't have VidEdit, you're out of luck: while Microsoft still licenses an updated version of VidCap 32, VidEdit has been EOL'd ("end of lifed") out of existence, and is no longer sold or distributed in any form. --Jan Ozer

While most of us struggle to capture and compress good-looking video, the developers of video editing software duke it out with features like advanced 3D motion paths, distortion and image warping, and gamma correction. And the inevitable price of added features--regardless of actual functionality to any particular title--is program complexity, making it even harder to perform the basics.

Few things are as worthless as tools too sophisticated for current skill levels.

In short, most of us don't strive to be Steven Spielberg, but would be plenty happy with better looking Indeo files, and advanced features a person would never use shouldn't have much to do with convincing that person that a video editing product will achieve this admittedly limited but obviously critical function. As more and more professionals turn to CD-ROM and video, there's a need for understanding what basic video editing toolsets can do practically. After all, it's not just multimedia developers anymore that work with video, but people working in human resource departments, or who are responsible for creating a marketing disc or two, or handling CBT as it moves in-house.

Working with three mainstream video editors--Adobe Premiere ($795), Asymetrix Digital Video Producer ($89), and Ulead's Video Editor from Media Studio ($349)--reveals the baselines and the basics from capture to compression, each in the end judged by comparing output quality. Looking at common advanced features proves useful too, in order to identify qualitative differences between the programs.

If you received Media Studio or Digital Video Producer (DVP) bundled with a capture board, you may still want to purchase Premiere to produce your best work, but that depends on what the work is. You need to know where Premiere falls short, or where DVP or even the venerable VidEdit from Microsoft is still your best option. And what you want will depend on your focus: if it's on CD-ROM publishing, for instance, you'll have more concern with compression-oriented features than with whether you can export edit decision lists (EDLs) in Grass Valley format.

Whatever your focus, there's no getting around the basics: video creation involves the four discrete steps of capture, editing, garnishing, and compression. The first step, video capture, is when you capture the video from your analog source. Critical here is the comparative ability to capture at high bandwidths without dropping frames, as well as the availability of advanced features like batch capture.

Next is editing the captured video to its final length and the collection of other assets, like bitmapped images and audio, onto the program time line. Most video editing programs can perform the basics; the difference here is tools that enhance precision and overall ease of use.

The third and most time-consuming step is garnishing, or enhancing video appearance with transitions, special effects, overlays, and titles. The nature and extent of video editing program options, as well as qualitative differences, can make one program's output look better than another.

The last step is rendering, or combining the whole enchilada into one compressed video file. If a video editing program can't produce a file that plays back smoothly from a CD-ROM, exceptional performance in the other areas becomes much less valuable. There are also some advanced features to consider, like the ability to compute an optimal palette and concatenate multiple compressed video files into one without recompression.

When it comes to video captured for digital playback, the first measure of an editing program is still how it stacks up to VidEdit and VidCap. In fact, there are a lot of good reasons for any video editing program assessment to refer back to these classics--frequently.

VIDEO CAPTURE, STEP NUMERO UNO

Return to Top

If you received Media Studio or Digital Video Producer (DVP) bundled with a capture board, you may still want to purchase Premiere to produce your best work, but that depends on what the work is.
Video capture is analyzed in two areas: features and performance. From a feature perspective, it's important to remember that most basic functionality comes from your capture board, not the software, since the latter simply accesses onboard options like capture format, resolution, and adjustment of incoming color and brightness. This means that all editing programs should be able to access the same capture board features.

From an architectural standpoint, DVP and Media Studio capture via a separate program, while Premiere's capture is integrated. Both approaches have their good and bad sides, and working with the two separate capture programs is relatively intuitive, especially for someone used to VidCap, since all controls are capture-related. In contrast, Premiere's capture controls are scattered across several menu items and relatively difficult to find; for example, you can't set the capture file from the movie capture menu, but rather from the general preferences window, and ditto for selecting machine control. On the other hand, once you capture a file with Premiere, you're in the editing program, instantly trimming the file and placing it on the time line. In most instances, this feels like a preferred approach.

Premiere also lets you save most capture settings into a .PCS capture settings file, although Premiere doesn't save perhaps the most critical pieces of information, the incoming color and brightness adjustments. These are preserved in the premiere.ini file, and are restored to their most recent setting every time you load the program.

Capture Features

Return to Top

In terms of common features, all programs enable both real-time and step capture via machine control over such equipment as the test bed laserdisc, although the level of machine control differs by program. Premiere and Media Studio provide VCR-like controls over the laserdisc that let you play, stop, start, and rewind from within the program; DVP doesn't, forcing you to use external controls. The DVP approach can be a problem with VISCA devices that don't enable external control once program control is engaged, and without software-based controls, you need to sever the link by disconnecting the cable from the deck to unfreeze the hardware controls, then manually set the location for the next capture--a tedious process that outweighs many of the benefits of computer control.

While DVP and Media Studio are limited to MCI devices, Premiere goes much further, supporting V-LAN and ARTI protocols within the program and RS-422 and other protocols through third-party plug-ins. This can be helpful when working with BetaSP and other advanced decks, but probably is most critical in non-linear applications rather than capture for compression applications.

Like VidEdit, DVP has a major fault of overwriting previously captured files without a warning, which can easily destroy the fruits of your previous capture. Premiere and Media Studio avoid this problem.

Keep in mind that video capture cards drop frames during capture when capture rates are set too high. When this happens, most developers prefer to reduce the capture data rate until the card captures all frames successfully. Most capture programs display dropped frame data in real-time so you can stop the capture and reduce the data rate, if necessary, before the capture is complete. The odd man out in this capability is Media Studio.

Capture Performance

Return to Top

Video capture boards are rated by their ability to capture at high data rates without dropping frames, and this is important because higher data rates translate to better video quality, which is essential to both non-linear editing and capture for compression. The board itself, however, isn't the only factor affecting performance; also contributing is the overhead imposed by the capture software, with more efficient programs enabling capture at higher rates without dropped frames.

The test platform was a Pentium 133 running Windows 95 with 16MB RAM, using a miroVIDEO DC30 capture card, capturing to a ProMax SCSI hard drive connected to an Adaptec 2940W controller. Video was captured at 640x480 resolution at 60 fields, and CD-ROM audio quality (44KHz, stereo, 16-bit), with the graphic mode set to 800x600x8-bit, and with preview disabled during capture. The hard drive was defragmented between each test.

Testing started at 5,800KB/sec, at which VidCap32 dropped no frames. If substantial frames were dropped using the other programs, the data rate was reduced to 5,600KB/sec, then 5,400KB/sec. Overall, the tests revealed why many capture cards ship VidCap32 with their products--the boards simply can't achieve optimum performance with either Premiere or Media Studio, though DVP is slightly better. This means that developers seeking advanced features like batch processing and VTR-like controls may be forced to reduce their capture data rate by ten percent or more to obtain them.

CD-ROM publishers shouldn't panic, however. Capture tested at 320x240 resolution, 30 frames per second, and the highest data rate the DC30 could generate, saw capture performance improve significantly. Both DVP and Premiere dropped no frames, while Media Studio dropped only three. For CD-ROM publishing, as opposed to non-linear editing, all three programs should be fine.

VIDEO EDITING 101, STEP TWO

Return to Top

After capture comes editing. If you've captured without machine control, the first task is usually clipping the extra frames from the beginning and end of the clip, the so-called heads and tails. In many applications, the next stage would be compression to final output, but for more sophisticated applications, you may want to combine two or more clips, perhaps adding titles, transitions between clips, or special effects.

To facilitate this activity, all video editors use a "time line" paradigm that commonly shares many elements. DVP's screen is typical: In the upper left-hand corner is the Media Window, which collects all assets integrated into the final video. On the right side of the screen is the Player window, which serves as DVP's clip editor, used for trimming heads and tails from the captured video.

Along the bottom of DVP's screen is the time line, showing the two videos contained in the Media Window. The time line has four component tracks: video, audio, transition, and overlay. The video tracks contain all visual footage, including animation and bitmaps. The transition track contains all transitions between video A and B, selected from a floating Transition window. The audio tracks contain audio from the videos and can accept discrete audio clips from other sources, as well. The overlay track, often called the S track for superimposition, contains titles, graphics, and video superimposed over the main A and/or B video tracks via chroma keying and similar techniques.

Gathering Your Assets

Return to Top

Captured video clips are typically only one component of the final video. Most projects also contain bitmapped images, perhaps animation and other audio files. All three programs accept AVI and WAV files, Autodesk Animator FLC/FLI files, and sufficient bitmapped formats for most applications. Media Studio's ability to work with audio files embedded in AVI and MOV files is significant, because this saves a step when reusing audio already interleaved with another video file. Heavy Mac users will appreciate Premiere's ability to work with Macintosh filmstrip (FLM) files.

Some features simply deal with creature comfort issues that make working with the respective programs easier. Media Studio can't input multiple files at one time, which is a minor hassle when working with directories of files bound for the same video. On the other hand, Media Studio can preview all files before opening, including animation, which is useful when trying to identify the correct file. Media Studio also lets you double click on an audio or video track to load the file/open screen, another time saver that quickly feels essential.

Editing on the Time Line

Return to Top

Premiere Lite
Does your copy of Adobe Premiere taste less filling than the version discussed here? Well it could be that you have Premiere Lite, or Premiere LE as it's officially called. This is a feature-defoliated version of Premiere that Adobe put together to serve the needs of low-end capture cards. We spoke with Joyce Chung, Premiere product manager, to get the skinny on the features lost in LE. What follows is what she identifies as the major differences:
  1. LE is limited to three audio/video tracks

  2. LE has no 2D/3D motion capabilities

  3. LE has fewer effects, transitions, and filters, and won't accept third-party plug-ins

  4. LE's titler has no gradients, shadows, and has only limited drawing capabilities

  5. LE has no ability to export an edit decision list
Of the differences, CD-ROM publishers are likely to find the track limitation most burdensome. Cost to upgrade to the full version is $149. Details at http://www.adobe.com[LiveLink]. --Jan Ozer
The video editing software time line is the digital cutting room where assets are input, edited, and finally rendered. A number of features affect these programs' ability to perform comprehensive tasks, and their ability to make these features easily accessible to the user.

All programs let you save "projects," which includes all assets and editing characteristics like transitions and special effects. Only Media Studio, however, stores the filename in the file/open screen, like most word processors and spreadsheets, so you don't have to search for the project when you're ready to start working on it again.

One of Premiere's greatest strengths is project presets, which let the user specify time base, compression options, and preview options. Premiere ships with about 15 presets which can't be altered and allows users to build their own. Selected when loading the program, Premiere's presets let you forget about setting discrete output options each time you render a file, saving time and helping you avoid mistakes, and this is especially useful when you work with a number of different types of projects, such as non-linear editing and capture for compression.

While Media Studio doesn't offer presets, it does save output and compression options in its .INI file each time you exit the program. This helps when you consistently work on the same type of project.

The number of video and audio tracks these programs support controls basic editing capabilities, and while 99 may not be of much practical use to the average CD-ROM developer, two is unnecessarily restricting. With its two track limit, DVP, for example, can't overlay a video and place a title at the same time, since the same track is used for both purposes. And while most analog video editors work in Society for Motion Picture and Television Editors (SMPTE) time code, their lingua franca, most CD-ROM developers prefer to work in frames; Premiere and DVP support both metrics, but Media Studio only the former.

When moving assets on the time line, you often need to place the media at a point defined by another asset on the time line. For example, when adding audio to an animation file, you need to drag the audio file to the precise starting point of the animation. Premiere and Media Studio provide edit guides, or vertical lines that frame a clip on all other time line tracks whenever it's moved, providing a guide for aligning the clip with other assets. With DVP you're on your own, which complicates file synchronization.

Premiere enhances its edit guides with a "sticky" mouse that tends to stop the asset at each possible editing point along the way, hanging for just a brief moment before moving along to the next point, which lets you easily align the assets with precision. Media Studio takes its lead from the image editing world, and offers 99 levels of undo, an extremely helpful feature, since you don't always find your mistakes before making another editing decision.

Editing Essentials

Return to Top

All video editing programs enable viewing from various perspectives, from low-level views that display each frame to high-level views in which each frame on the time line represents a minute or more. Premiere's controls are located on the bottom of the time line, Media Studio's on the top right, and DVP's plus and minus buttons are on the left hand side. Locate these controls immediately, because you'll use them frequently and because knowing how to enable/disable these in a hurry will save you a lot of time and hassle. Media Studio, unlike the other two, also has an automatic option to fit the entire project in the time line, a fast lane to the big picture.

All three editors let you customize how the audio and video tracks are represented on the time line, which affects system responsiveness. For example, when displaying a bitmapped representation of the video, the program first scans through the audio and video files to approximate the content, and then paints the screen. This can take anywhere from several seconds to several minutes, depending upon the file length and video resolution. All programs offer an alternate view that displays only thumbnails of the first and last frames and the filename in between.

How much difference does displaying bitmaps of video frames make? With a 17-second video file in Premiere, you can scroll from one end to the other instantaneously when bitmaps are off. When both audio and video are represented as audio, it takes six seconds. Loading the same file in Media Studio with bitmaps off takes less than half a second. With bitmaps enabled, it takes about 16 seconds. Common editing functions like moving an asset on the time line or changing the zoom factor also take much longer when bitmaps are displayed. For such reasons, it's usually fastest to edit with bitmaps disabled.

Another feature to be aware of is "snap to edges." This feature ensures that when you move two clips together on the time line they actually concatenate. With snap to edges disabled, there's always a risk that one or two open frames will lodge between the two videos, especially when you're working in big picture views. Usually, you won't notice the open frames until you spend a couple of hours compressing the project, and then play the clip back--black gaps between video clips are usually pretty hard to miss. To prevent this, keep "snap to edges" enabled.

Editing Creature Comforts

Return to Top

In most instances, it's best to edit video in the clipping or player windows offered by all programs, but sometimes it's more convenient to edit after placing the asset on the time line. These kinds of situations really start to highlight DVP's deficiencies.

Drag duration edits are accomplished by grabbing the bitmap, animation, or video file with the mouse and dragging it to the proper size. Drag edits are especially helpful when working with background bitmaps, because you can easily drag the bitmap to the required length, rather than entering duration via menu commands. Media Studio and Premiere offer drag duration edits, DVP doesn't. Premiere takes this one step further by offering in and out flags which set physical beginning and end points on the time line.

Both Premiere and Media Studio offer trimming windows that let you see up to five frames before and after the edit point to precisely adjust frames where two clips abut. This feature dates back to the old "measure twice, cut once" film editing days, where razors cut celluloid tape and an accurate trim mechanism was critical to smooth transitions. While undoubtedly beneficial in non-linear editing applications, most CD-ROM publishers can obtain sufficient precision without using the trimming window.

Speaking of razors, this is one tool that is as valuable in the digital domain as it was in the analog. Razor functions cut a video into two segments, leaving both on the time line, which is incredibly useful when applying special effects like fades to black that only impact the initial or final few seconds of video in a clip. In DVP, which doesn't have a razor function, you have to split the video into two segments in the player window, which is cumbersome and time consuming.

Advanced Editing Features

Return to Top

Suppose you decide to add a 15-second title to the start of your three-minute clip comprised of ten discrete videos and nine transitions. Ripple edits, an advanced feature found in Premiere, lets you add the title and then automatically "ripples" the other clips back to their proper position, preserving their relative spacing and transition placement. Media Studio lets you get close to the same effect by grabbing all assets on the time line and moving them back 15 seconds, but this is neither as convenient nor as accurate.

Another unique Premiere feature is the project trimmer, which lets you reclaim valuable space on your hard disk after editing. Note that when you trim a video in an editing program, you don't change the actual video file on the disk. For example, say you were capturing a 30-second clip and ended up with 45-seconds, the 15 extra seconds representing heads and tails. In the clip window you cut the heads and tails and send your 30-second file to the time line, but the disk file still contains an extra 15 seconds of video, at up to 6MB/sec. In the ten video examples above, this means up to 900MB of extra video, which is enough to strain even the largest disk system. The project trimmer provides the mechanism to delete unwanted video files from the files on disk, reclaiming the wasted space.

Synchronization between audio and video is key to final appearance, and Premiere and Media Studio preserve this by locking audio and video tracks copied from the same video file, and treating them as one file during all subsequent edits; DVP doesn't, forcing you to separately and carefully move the audio file to the exact same location as the video file each time you move the video. Media Studio and Premiere also let you adjust audio volume manually on the time line with finger controls, a nice convenience.

Speaking of creature comforts, video editing is a very hands-on task, and it's nice to have the controls instantly available via right mouse clicks. Both Premiere and Media Studio make this so.

One of the most important creature comforts is, of course, program speed, which can be compared by loading a 17-second, 640x480 raw file into each editor with the zoom ratio set to one second and the bitmaps on, and then shifting the zoom factor to one frame and timing how long it takes for the program to return editing control. For the most part, Premiere proved faster than the other two programs, usually only slightly faster than Media Studio and much faster than DVP. DVP's times indicate that it's not really designed for real-world non-linear editing, which involve very large files. Even with 320x240 files, DVP was much, much slower than the other two, and while you can reduce the wait in DVP by working with bitmaps off, unless you're working with extremely small files, count on a wait with DVP.

Indeed, in terms of pure functionality, DVP's two audio/video tracks can prevent developers from completing even moderately complicated projects, or force them to build the product in stages, adding layers along the way. Otherwise, the three programs offer similar functionality, but vary greatly in ease of use. You can "get there from here" from each editor, the ride is just much more pleasant with Premiere and Media Studio.

GARNISHING PRAISE, STEP THREE

Return to Top

Another feature to be aware of is "snap to edges." This feature ensures that when you move two clips together on the timeline that they actually concatenate.
Once your assets are captured and on the time line, it's time to garnish your video with transitions, filters and special effects, keying, and titles.

Transitions are mechanisms for moving smoothly from one clip to the next. The simplest transition is none at all, a "cut" where the first frame of the second video immediately follows the last frame of the first. Other simple transitions include fades--where the first video fades out to either white or black, while the next fades in, from white or black--and wipes, where a line moves across the screen "wiping" off the first video and "wiping" on the second. For simple cuts and wipes, DVP is probably sufficient. As you move up on the creative scale, Media Studio offers more transitions and the most options, although Premiere's anti-aliasing filter adds a touch of professional quality not available in the other two programs.

Filters break down into two categories: corrective filters and special effects. Once again, the sheer number of filters matters little so long as the necessary filters are present. Corrective filters fix problems in the video itself and fall into two subcategories: color balance and brightness. Special effects change the basic look of the video for artistic effect. DVP offers all the basics, but little else, and Media Studio tends to offer greater flexibility with their filters, which advanced users will appreciate, while Premiere handles cropping and scaling with aplomb. Premiere's cropping and scaling feature shouldn't be underestimated, however, since many video capture cards have equalization controls, making it highly likely that the fastidious video developer will be cropping pixels, and, if working in Premiere, glad they could do it in one step.

The overlay process is used to combine elements of two or more clips into a single video and overlay works through "keying" techniques that "tell" the editor which part of the video to ignore and which to "overlay" onto the final rendered video.

For the most part, editing programs treat titles like any other bitmapped image: you place titles on a video or overlay track, integrate it with your other videos with keying techniques, and move the title around the screen with motion controls. For this reason, the title generation utilities included in video editors are similar to limited use graphics editors primarily oriented towards text creation. However, DVP ships with a special 3D title editor for more advanced operation, while the full version of Adobe Premiere ships with Crystal Flying Fonts, which serves the same purpose.

Overall, Premiere ranks at or near the top in all garnishing functions, most clearly in cropping/scaling, keying, and overall program speed. The only significant qualitative advantage over Media Studio is in keying, however, with Ulead's editor generally performing the same functions. Both programs offer several qualitative advantages over DVP, and many artistic ones, and DVP proved much slower in most critical functions.

Transitions

Return to Top

Contrary to popular opinion, the number of available transitions isn't the most important program feature. Most professional video editors will tell you that the best transitions are those that go unnoticed, and that simpler is usually better. This is especially true when editing for compression, since garish transitions typically create additional motion, limiting interframe compression and degrading compressed quality.

No, the sheer number of available transitions isn't key---it's the quality of the implementation, the ability to customize and ease of access to the features. This is what truly sets programs apart.

While the sheer number of transitions isn't critical, all programs store available transitions in a dialog box, allowing the user to scan through and drag or otherwise select the desired transition to the time line. Media Studio organizes their 103 transitions into 12 discrete categories, like rolls, wipes, and 3D transitions, and lets you build your own custom groupings. The other two programs pack their transitions into one big dialog box, which makes finding the right transition a bit tougher to both select and find, especially if you have to work through Premiere's alphabetized list of 75.

All three editors let you preview the transitions with the actual source videos, which helps select the best-looking transition. Media Studio and Premiere also let you set transition duration, simplifying the editing process. With DVP, on the other hand, to create a one-second transition, you have to move the clips so that they overlap by precisely one-second, which often requires that you change to a low-level time line view. With the other two programs, you simply drag the transition into place, set the one second duration, and then move the two clips to the required locations.

Finally, drag and replace lets you sample new transitions simply by dragging a new transition from the dialog box and replacing the old, and Media Studio is the only program offering this option. DVP is similar in that once you select a new transition and close the dialog box, the time line automatically updates. In contrast, Premiere forces you to delete the old transition first, which tends to be a pain since the transition window moves behind the construction window when deleting the transition, forcing more than a few extra mouse clicks.

Transition Customization

Return to Top

Transition customization options fall into two ranges--creative and qualitative-- with the first allowing the producer more creative choices, and the latter affecting transition quality. Common creative options include direction, where one wipe transition lets the producer wipe from right to left, left to right, top to bottom, and bottom to top. Orientation is a similar option, letting the producer rotate a clock-wipe transition either clockwise or counter-clockwise. Both Media Studio and Premiere let the developer place a border on the transition effect, set its width, and choose a color. Media Studio also enables a "soft" edge which blurs the hard lines of the transition.

Multiples is the ability to divide the transition into a number of smaller windows, all accomplishing the same basic transition. For example, applying a vertical multiple of two to a wipe creates two wipe effects, the first starting at the left edge and working through to the middle of the video, and the second working simultaneously, starting at the middle and working through to the right edge. Applying a horizontal multiple divides the transition window north/south, creating four simultaneous wipes. Media Studio leads the pack here, offering multiples on virtually all transitions. Premiere has one or two multiple transitions, and DVP has one.

Premiere is the only editor with quality-related options, and specifically its customized anti-aliasing. One constant problem with computer graphics is aliasing, also known as the "jaggies," which occurs most frequently on hard diagonal edges. Since many transitions use hard diagonals, aliasing is often a problem.

Premiere's anti-aliasing, available in three levels, blurs this aliasing, reducing the starkness of the jagged edges. When transitions feature diagonal lines, this feature makes Premiere smoother than the other two editors, though only slightly.

There are also various transition files--standout effects--worth noting. One is Media Studio's killer "Burn" transition, reminiscent of the final transition in the introduction to Bonanza, where the title sequence shows a burning map of the Ponderosa in an expanding ring, then transitions to Dad, Hoss, and Little Joe, together on horseback.

Not all transitions are created equal, however, especially when 3D effects like page curls from Media Studio and Premiere are involved. The aliasing on the perpendicular line at the root of the page curl in the two clips reveals a smarter angle of attack chosen by Adobe that really limits the jaggies. On the other hand, Adobe's other edges show more jaggies, though somewhat smoothed by the anti-aliasing filter. What really stands out on the attention to detail scale, however, is this: all of Adobe's page curl transitions have shadows beneath the curved edge, just where they would be in real life; Media Studio's don't.

Corrective Filters

Return to Top

Not all transitions are created equal, however, especially when 3D effects like page curls from Media Studio and Premiere are involved.
Corrective filters fall into two categories: color/brightness and clipping/scaling. Many times after capturing video, you'll find that the color is a bit too dark, or perhaps tinted incorrectly. And while it's always preferable to resolve these issues during capture, sometimes you can't, and all three editors provide both brightness/ contrast and either red/green/ blue or hue/saturation/brightness color controls, allowing you both color and brightness levels.

Note, however, that Premiere and Media Studio let you customize settings at both the start and finish of the clip, adding a level of precision and an exceptionally simple way to fade the video to or from black or white. DVP doesn't allow customization of their brightness/color filters, but has dedicated fade video filters, a nice convenience for beginners.

Premiere starts to break out with clipping and scaling. You clip unwanted pixels from the video either to address capture card equalization problems that can produce rows of black pixels on one of the video edges, or simply to cut the video to the desired resolution. You scale to adjust the entire video to a new resolution, say to reduce a 320x240 video down to 176x144 resolution for streaming over the Internet. All three programs can clip, and all can scale. However, they vary in terms of how they implement these features, which affects usability.

Here's a scenario: Say you've designed your application for 320x240 video files, but your capture card caused a row of four black pixels on the video bottom. What you'd like to do is to crop the unwanted pixels, then scale back to 320x240, preferably in one step, so the video fits your application. Premiere handles this best with two separate filters; the first is clipping, which removes the pixels and leaves the video at its new resolution, and the second is cropping, which clips the pixels and then stretches back to the original resolution. Premiere also enables compression time cropping and scaling (they call it clipping), allowing the user to adjust all component clips at one time. The "better resize" option is a resizing algorithm from Adobe sister product PhotoShop that reportedly avoids scaling artifacts that can occur when adjusting video resolution.

Media Studio's approach is more awkward. While you can crop unwanted pixels from any video edge (in the compression options screen, rather than as a filter), you can't resize back to the original resolution in one step--you have to crop, then reload the video and expand it back to the original size. In addition, since all cropping is performed at compression time, rather than as a filter on the time line applied to arbitrary clips, you have to crop all videos, not just those that need it. This also makes for additional steps.

Similarly, DVP can clip unwanted pixels or scale to a different output size, but not both in one step; in addition, cropping and scaling are not implemented as filters but as a separate menu command (file/ scaling). Unlike the other two programs, DVP's clipping control doesn't show the actual video when clipping, making it tougher to produce accurate results.

Artistic Filters

Return to Top

Artistic filters are most commonly used for fading to and from white or black at the start or end of a clip. All three programs let you modify your clips in these fashions, once again using different techniques.

DVP works most simply with dedicated fade to/from black and white filters which apply over the duration of the clip. With Premiere and Media Studio, you work with the standard brightness/contrast filter, which lets you adjust the values at the start and end points.

Fading is the single most important reason to be able to cut a video clip into two segments on the time line. To fade to black in the last three seconds of a 30 second clip, you use a razor tool to cut or separate the final three seconds of the clip from the other 27 seconds, and apply the brightness/contrast filter to the stub clip. If you can't cut on the time line, you have to use the clipping window to create two clips, which is much less efficient.

In general, Media Studio is more customizable than either of the other two programs. For example, Premiere offers blur, blur more, and Gaussian blur filters, all without user options or the ability to preview the filter over the source video. In contrast, Media Studio offers blur and Gaussian blur, both completely adjustable for start and ending values, and both with preview over source footage. In general, advanced users may find themselves getting frustrated with some of these limitations in Premiere.

Media Studio is also unique in its ability to apply a filter to a clip region, allowing you to blur a subject's face without blurring the entire frame, for example. Both Premiere and Media Studio let you paste filter attributes from one clip to another, a nice time saving option.

Audio Filters

Return to Top

The most commonly used audio filters are fades, used to fade in from silence at the start of a clip and fade down at the end. All three programs let you increase or decrease audio volume by grabbing an audio volume line beneath the audio wave form and moving it upwards or downwards. Premiere and Media Studio offer their controls conveniently on the time line, while DVP opens a separate window.

Unlike video fades, which force you to cut a clip into two components to fade to black at the end, you can start your audio fade from any point in both Premiere and Media Studio. You simply anchor the clip by touching the audio volume line at the point you want to begin your fade and then drag the stub downwards.

A cross-fade occurs during transitions when the first clip's audio fades to silence while a second clip's audio fades in from silence. Both Premiere and Media Studio offer automatic cross fade tools, a nice convenience, while DVP makes you apply the cross fade by hand.

Media Studio offers the widest range of audio filters, no doubt pinched from its sister audio editor. Unfortunately, in both Premiere and Media Studio, you can't sample the filters when you select them, you have to apply the filter and then preview. This makes audio filters somewhat more difficult to access than the video filters. For example, in Media Studio you can't test the amplitude filter without selecting a value and previewing the entire clip, an unnecessary step.

Keying the Basics

Return to Top

The most common overlay technique is called chroma keying or color keying. Video editing programs implement a number of keying techniques that are variations on the same theme, to allow the developer to describe which portion of the video to ignore, and which to include in the final rendered sequence. For most developers, the sheer number of keying options isn't critical--just be sure to film using a technique supported by your editor, and in most instances chroma keying is just fine. The sheer number of layers is important, as DVP, with one superimposition line, can't place a title and chroma key at the same time. The 99 layers offered by Premiere and Media Studio are both more than adequate.

In most instances, you'll have to adjust the tolerance of the chroma key, increasing or narrowing the definition of the keying value to completely eliminate the key color. Tolerance adjustments are critical to achieving good results, and the different programs handle keying with varying levels of success.

All three programs offer these basics, and the ability to preview over the actual video, obviously essential to getting good results. Premiere takes preview an extra step by letting you zoom the video in the preview window and move the video around to closely examine the edges where keying typically breaks down. With Media Studio and DVP, you really have to preview in the time line to gauge your results. Both Media Studio and Premiere let you adjust similarity at both the start and end points, useful when the subject matter of the video changes.

Variable keying is an advanced control that adjusts the intensity of the overlaid videos, especially when more than one overlay is active. This is how producers fade multiple video components in and out of a scene, like in the movie Ghost, when Patrick Swayze appeared ghostlike when appearing onscreen after his untimely death. More common applications might be fading text and graphics into a video, rather than placing it onscreen at 100 percent strength. Premiere has similar variable keying capabilities to Media Studio, but DVP, with only one superimposition track, doesn't.

For simple, one-track overlay, all three video editing programs run neck and neck. But Premiere offers smoothing, which enhances final appearance significantly, something not offered by either Media Studio or DVP. Keep in mind that the mere ability to select a tolerance level doesn't mean you wipe out all the blue. Even when using Media Studio's soft edges control to smooth the edges of the overlaid video, the jaggies are eliminated, but blue halo effects can make the video unusable.

Keying appears to be one area where Premiere produces more polished results than either of the other two products. If you're developing content with lots of overlays, Premiere may be your best choice.

Motion Paths, the Basics

Return to Top

Most motion controls probably fall into the most hyped, least useful variety of video editing program features, especially for CD-ROM publishers, because motion makes video more difficult to compress, and so degrades overall quality. Two-dimensional motion is movement across the X and/or Y axis of the video, and common examples are scrolling credits, which start at the bottom and end at the top, or spinning logos or other graphics that rotate around a fixed axis. These types of motion are well within the capacity of all three video editors, as is resizing an object to make it appear as if it's getting closer or further away, a faux 3D effect.

Three-dimensional effects range from spinning on a Z axis, like old rotating gas station signs, to simulated views around a circle or cylinder. These artistic, complicated effects are fun, but probably best left to true artistic professionals.

Motion paths work with the editor's time line which represents clip duration. At any given point on the time line, you can create a "key" frame with unique X/Y placement coordinates as well as the rotation, zoom, and delay levels. In essence, the clip's motion is its journey from key frame to key frame, adjusting at a constant rate during the move from the coordinates of the first to the coordinates of the second. For example, to scroll a text title from top to bottom, you would move the start square to the top of the visible area and the end square to the bottom, leaving the other controls alone. To add a 360 degree spin, you would change the final rotation coordinate to 360, and the title would spin one full turn over the duration of the move. To build a stationary, spinning logo, you would place the logo in the same position on the screen at the start and finish but change the rotation. Premiere's zoom control and Media Studio's sizing control let you zoom the image closer to or further from the viewer, creating the appearance of 3D motion. Both products also let you warp or distort the clip, again over time.

Sub-pixel rendering proves to be more than just a buzzword. While Media Studio and Premiere were relatively smooth at all angles in motion path effects, DVP showed severe jaggies throughout the rotation, causing noticeable image degradation. The lesson: Even when performing relatively simple motion edits, Premiere and Media Studio will outperform DVP.

Titling

Return to Top

Most video editors can use all system fonts and modify font size, style, justification, and color. All editors anti-alias text objects for smooth appearance, but Premiere's features for titling start to wax while Media Studio and DVP's feature sets start to wane. Premiere offers kerning, or the ability to adjust the distances between the text letters. In addition to horizontal fonts, Premiere supports vertical titling, a useful creative option. Premiere is the only editor to include drawing tools for boxes, circles, ellipses, and irregular objects, and the ability to apply a gradient pattern to any text or graphic object.

Like most graphics editors, Premiere treats text as an object, allowing you to manually place it in the frame. In contrast, there is no WYSIWYG placement in Media Studio or DVP, but instead you place text using spaces and lines like an old DOS word processor, and hope for the best. Adobe maximizes the creative potential of these tools by letting you create the title over the actual video frame itself, a unique feature among these programs.

As a result, Premiere offers more options and is much easier to use, providing a significant advantage over the other programs in title-intensive projects. Uniquely, Premiere even lets you save title files for later use in other projects.

Which is not to say that DVP doesn't have its own charms. A separate program, Asymetrix's Titling Specialist, creates three-dimensional titles that can be rendered as AVI files and added to video presentations. As with most titling programs, you can specify font, size, and attributes. In addition, the Titling Specialist lets you create three-dimensional titles with varying thickness, colors, and surface materials.

In Asymetrix's Titling Specialist, you control the motion across the X,Y axis with motion paths with key frames, selecting from canned motion paths or creating your own. In addition to motion across the X and Y axis, you can spin and rotate the title, and move it closer and further from the viewer. You can also change the lighting implemented, choosing between back and front lighting, a flashlight, and many other effects.

An educated guess is that the Titler is a derivative of Asymetrix's highly regarded 3D FX program, a general-purpose 3D creation program. Either way, this function alone might justify DVP's $79 purchase price.

COMPRESSION AND OUTPUT

Return to Top

A fact of CD-ROM multimedia development today: Most video captured and edited for digital playback is destined for compression into Video for Windows' AVI format. With the standard for compression performance remaining Microsoft's VidEdit, writing compression routines that match VidEdit's results shouldn't be difficult for programmers, in theory, since all codecs fit into the prescribed Video for Windows architecture. However, the initial compression APIs Microsoft supplied were poorly documented and incomplete, and, arguably, didn't improve with Windows 95.

As a result, most first-generation video editors compressed incorrectly, resulting in files that failed to achieve the target data rate or suffered from defective audio/video synchronization or incorrectly computed CD-ROM padding. For this reason, many CD-ROM developers to this day process their videos with another editing program, but then compress the raw file with VidEdit.

If a video editor can't match VidEdit's performance with your target codec, you have to render the finished file in a raw format and compress with another tool. At the very least, this means another step, complete with pretty stiff disk space requirements. If you don't have a copy of VidEdit hanging around the lab, it means you have to purchase an editor that can get the job done.

Basic Compression Performance

Return to Top

Three encoders--Intel's Indeo 3.2, Indeo video interactive, and Radius's Cinepak-- were tested with a five-second, real-world clip comprised of talking head and action footage, with a wipe transition in between. All codecs were compressed at 150KB/sec, using a key frame setting of 15, CD-ROM padding engaged, and quality set to the codec's default value.

The same clip and a short animation sequence were also tested with Microsoft's Video1 to explore the three editors' palette management skills. Video1 is still used for real-world videos targeted towards the 8-bit display environment, and is the best VFW codec for compressing FLC/FLI animation to add audio and enable streaming from CD-ROM.

Compression with Indeo video interactive (IVI) occurred with this codec's advanced features, scalability and bidirectional encoding enabled. Both Premiere and DVP closely matched VidEdit in both data rate and appearance, and while Media Studio's data rate was substantially higher than VidEdit, appearance was similar. Several other IVI files with Media Studio were compressed without similar data rate spikes, but this issue bears watching if you're working with close tolerances.

With Indeo 3.2, both Premiere and DVP once again closely matched VidEdit's performance in both data rate and appearance. However, Media Studio's video data rate was inexplicably about 32 percent lower than VidEdit (93KB/ sec versus 138KB/sec), resulting in the gauzy looking video shown. Several other clips compressed with Indeo 3.2 by Media Studio showed similar results, and so if you're compressing with Indeo 3.2, Media Studio is probably not your best option.

With Cinepak, Premiere's data rate was about 10KB/sec higher than VidEdit, primarily due to excess CD-ROM padding in the Premiere file (12KB/sec, as compared to 9KB/sec). On other clips, Premiere generally duplicated VidEdit's CD-ROM padding numbers, so this appears to be an isolated problem. Premiere's visual quality was virtually identical to VidEdit. With Cinepak, DVP did Premiere one better, matching VidEdit's data rate and visual quality almost exactly. While Media Studio produced acceptable data rates, visual quality was sub-optimal on the test clip and several other clips compressed on several different computers to verify results. The program produced ugly blotches on key frames, rendering the compressed footage unusable.

Palette Management

Return to Top

Most Windows video graphics cards display in 8-bit, 16-bit, or 24-bit color depth, with 8-bit systems predominating. When a computer is in 8-bit graphics mode, display is limited to 256 colors; this collection of 256 colors is called the palette, and all screen elements must be painted with colors contained in the palette. The 256-color combination is not fixed, and palettes can and do frequently change. But at any one point with 8-bit, only 256 colors can be used to describe all the objects on the screen.

All graphic objects, including animation, video, and bitmapped images, have their own palette. When a graphic object displays, Windows makes certain that its palette is installed. If it isn't, Windows automatically changes the palette to that of the new object by momentarily blanking out and "realizing" the colors of the new palette. Known in the trade as "palette flashing," this effect can be quite distracting.

Cinepak and both Indeos are native 24-bit codecs that use over 16 million colors to describe their compressed video. When displaying in 8-bit mode, Cinepak and each Indeo have to drop from 16 million to 256 colors. To conserve file size and preserve display rate, none of these codecs store palette information in their file but rather simply decompress to the same fixed palette for all videos. To minimize the potential for distortion, 24-bit codecs "dither" or draw minute geometric pixel patterns of various sizes to simulate colors not contained in the palette. Because these codecs each decompress to their own palette as a video plays, developers need to use one of several techniques to avoid palette flashing. Even then, however, the video is dithered, which degrades appearance.

The two 8-bit codecs, Video1 and RLE, don't have either the palette flashing or the dithering problem. Eight-bit codecs can "hold a palette," which allows developers to select one palette for a screen or presentation and compress all videos and other graphics to that palette, and they don't have to dither because the video is already described in 256 colors or less. For these reasons, many developers consider Video1 for mass-market multimedia products that will probably play on lower-end machines with 8-bit displays. However, Video1 simply doesn't have the horsepower for action footage, which means that Video1 does a great job only for low-motion videos and certain animation.

To compress video to a fixed palette, the editors must be capable of two tasks at which VidEdit excels--calculating an optimal palette for the graphics elements in the presentation and applying a previously calculated optimal palette. It also helps if the programs can save the palette as a separate PAL file for subsequent use.

In fact, only DVP can import, compute, and save a palette file, though its import capabilities are limited to only Windows palette files with the PAL extension. DVP can also compute a palette from a partial file, which can be a huge time saver when working with large animation files. Media Studio can grab a palette from a BMP file in addition to PAL files, while Premiere works with PAL, BMP, and AVI files, at least in theory. Loading a palette from a number of AVI files into Premiere was unsuccessful, resulting in an "error reading file" message, even from files compressed by Premiere that loaded normally into the time line.

When computing an optimal palette for a video file, Media Studio and DVP matched VidEdit's palette very closely on both the animation and real-world video. Premiere performed well on the real-world video but faltered on the 640x480 animated sequence, missing virtually all primary colors. When Premiere was tested using a smaller 320x200 animation, the program computed an appropriate palette.

Media Studio was the star when compressing the full-screen animation, equaling VidEdit's quality at a substantially lower data rate (49KB/sec versus 188KB/ sec). Premiere mangled the first few frames with excessive blockiness, and DVP alternated between smooth and blocky frames. With the 320x240 (partial screen) animation file, all the programs produced files of similar quality.

When it comes to real-world video, Premiere bettered VidEdit's visual quality at a lower data rate. While DVP matched VidEdit's data rate, visual quality was noticeably worse than VidEdit. Media Studio had problems with Video1 when compressing difficult footage that stressed the target data rate, producing a data rate of 822KB/sec.

THE END GAME: ADVANCED COMPRESSION OPTIONS

Return to Top

When it comes to advanced options, Adobe Premiere is clearly one generation ahead in terms of creature comforts, codec support, and compression enhancements.

What's the first thing you want to do after compressing a file? You want to play it and you want as much relevant information about data rate and other file statistics. Premiere excels here by loading the file into its clip window, which enables a movie analysis that provides comprehensive audio and video file statistics, including a histogram showing streaming data rate. Neither DVP nor Media Studio offer anything like it.

Another unique Premiere feature is batch compression of Premiere projects. This allows developers to edit a number of captured clips, cutting heads and tails, adding filters, titles and other effects, selecting output options and then saving the project. When it's time to go home, you can queue up the projects for overnight or weekend processing, which makes for a big time saver. Neither DVP nor Media Studio offer a similar feature.

Premiere was also the first to focus on filtering as a way to improve video quality and to place a number of options in their compression menu, saving time for those who perform very little time line editing. At compression time, you can select either a blur, Gaussian, or median filter to assist compression performance. DVP offers a blur filter, while Media Studio offers blur, Gaussian blur, noise reduction, and an average filter that should offer the same benefits, but none are offered at compression time. Note also that both DVP and Media Studio allow the user to customize filter settings on the time line while Premiere doesn't, neither at compression time nor on the time line. And while both Premiere and Media Studio offer compression time clipping, only Premiere can scale the video back to the original resolution, using the scaling algorithm from PhotoShop to avoid scaling artifacts.

Key Frame Placement

Return to Top

Most compression formats use two types of frames: key and delta frames. Key frames--I frames in MPEG lingo--standalone and are compressed without reference to any other frame. Delta frames--B and P frames in MPEG speak--are compressed based on their differences from other frames.

Key frames serve a number of purposes in the compressed bitstream. First, since key frames are compressed without reference to any other frame, they can be decompressed very simply, and therefore act as an entry point when randomly accessing the video stream. That is, to seek to a delta frame, you typically decompress the immediately previous key frame and then scan forward. For this reason, interactivity--the ability to move quickly to random points in the clip--is optimized when entry points are key frames.

Second, key frames are larger than delta frames and able to produce a high-quality frame even at scene changes, which can dramatically degrade delta frame quality. Placing a key frame at scene changes therefore optimizes quality for both the key frame and all delta frames that reference the key frame.

For these two reasons, the ability to place a key frame at desired locations can improve both quality and performance. However, until Premiere 4.2, publishers were forced to select one key frame interval that was applied uniformly throughout the video. New in version 4.2 is the ability to place key frames at edit points, which automatically addresses many scene changes, and also at random markers on the time line, providing completely random placement. A new dialog box, accessible from the compression options screen, enables these functions.

This feature was tested by compressing clips with several markers and edit points using Indeo 3.2, Video1, Cinepak, and Indeo video interactive. With all codecs except for Indeo 3.2, the feature worked as advertised, placing key frames at the appropriate frames and then returning to the regular key frame interval. Indeo 3.2 blithely ignored Premiere's commands, placing key frames at the specified key frame interval.

Concatenation

Return to Top

Another important creature comfort, at least in certain, limited situations, is the ability to abut several previously compressed video files without recompressing them. This technique is used to join files that need different key frame intervals for joining together files developed at different times, or for animation or screen capture files that need key frames placed at irregular intervals. To abut files without recompressing, they have to be the exact same resolution: If compressed with Video1 in 8-bit mode, all the files must use identical palettes. Key frame intervals and data rates can be different, however.

Interestingly, the different editors have different capabilities in this regard. DVP was the overall best performer in concatenation, combining files compressed with Indeo 3.2, Indeo video interactive, Cinepak, and Video1. Premiere was next, combining all formats, save Video1. Media Studio brought up the rear, successful at combining only Cinepak and Indeo 3.2.

IN THE END...

Return to Top

As the jazz men used to say back in the Roaring Twenties, "It don't mean a thing if it ain't got that swing." For publishers, this roughly translates to "If you can't compress accurately, you can't place it on a CD!"

Overall, Media Studio was generally neck and neck with Premiere until the end game. At compression time, however, Media Studio faltered with Indeo 3.2, Cinepak, and Video1 with real world videos, and the lack of a histogram or other data analysis tool makes these problems difficult to address. If you plan on using Media Studio for CD-ROM publishing, you'd better have a copy of VidEdit or another program handy.

And users should also note that while Asymetrix's DVP struggled in several areas, a major update to the editor is scheduled for late first quarter 1997 release. In addition to addressing several of the issues that arose in testing, the company says the new version of DVP will also break new ground with enhanced ease-of-use features.


The Take on Transitions

Return to Top

Most professional producers tend to minimize the use of transitions, pursuing the creative attitude that the best transitions are those that are barely noticed. There are other good reasons to use "low octane" transitions. From a compression perspective, transitions are "motion," which like other video noise, degrades overall quality. Usually, the more exotic the transition--like tumbling videos or 3D page curls--the more motion created and the more image degradation.

How much degradation? We tested a number of transitions and fades by compressing a short clip with the Video1 codec to 150KB/sec. Of course, Video1 isn't the most industrial-strength codec, but all lossy codecs will respond similarly, albeit not to the same degree.

HIDE/REVEAL VERSUS PUSH

Hide/reveal transitions are those that keep both images stable, clip A on top of clip B, and then use some mechanism to hide clip A while revealing clip B. Common hide/reveal transitions are wipes, clocks, irises, diamonds, and other transitions that maintain both videos in the same visual plane. Push transitions are those that use clip A to push clip B from the visual area, simulating, kind of, two simultaneous pans in the video window. Common push transitions are the push, slide, and barn doors.

Major quality differences between the two general types of transitions can be very noticeable; in our test, the wipe transition, a type of hide/reveal, maintained good fidelity throughout. A push transition showed much more pronounced degradation.

It's interesting to note that from the viewer's perspective, quality differences notwithstanding, these transitions are almost indistinguishable. Thus you can increase quality significantly with minimal impact on creativity.

SIMPLE IS BETTER

Whether you decide to use a hide/reveal transition or not, in all instances, simpler transitions are better than more exotic ones. Examples? The common dissolve isn't a hide/reveal transition, but the amount of motion perceived by the codec is surprisingly small. On the other hand, dissolves come in many flavors, including the fizzle, which may look beautiful in the analog domain, but, well, fizzles in the digital.

3D IS OUT

Three of the 3D transitions available in both Premiere and Media Studio are the motion transition, the page curl, and the barn door, and we tested them.

The results? The motion transition spins the new video in over the old, and as you might expect with all that motion, it creates extreme artifacting. The page curl maintains video quality surprisingly well, although it shows blockiness in the page back and also in the video. Finally, the barn door transition, which the first video track swings away like a barn door, is perceived as significant motion by the codec, producing blockiness that degrades image quality.

The advice? Stay away from most 3D transitions, since their motion means artifacts for codecs.

FADE IN/FADE OUT

How about fading in from black at the beginning of the sequence and fading out to black at the end? You might conclude that a fade involves what the codec might see as a heck of a lot of motion, and you'd be right.

The lesson on fades? If you have to use them, make them quick. Long, slow fade to black may look artistic in some cases, but not at 150KB/sec.

THE BEST ADVICE

Probably the best advice for both transitions and fades is to test them all at your final compressed data rate before you become too attached to them. We hate to limit creative artistry, but compression artifacts are a real-world factor that must be comprehended in the creative process. --Jan Ozer


The Long View on Preview

Return to Top

While many edits are mechanical in nature, an equal number involve subjective, creative decisions that benefit from immediate feedback. Most video editors provide a preview function to provide this feedback.

To prepare the preview, the editing program must assemble all assets, implement transitions, filters, special effects, and motion controls and draw all titles, presenting the user with a composite clip of the final video.

Adobe Premiere, Asymetrix Digital Video Producer (DVP), and Ulead's Media Studio each use different preview schemes. Premiere displays the preview in a standalone window that launches when processing is complete. Previewed video plays back in real-time, and you can see the file again by pressing enter after the first preview playback. Unfortunately, Adobe doesn't provide a slider bar or other playback control to navigate to particular frames, and your only option is to play the preview back from start to finish in real-time.

Media Studio has a somewhat similar scheme, but unlike Premiere, this program displays the clip during preview, providing instant feedback, and then launches a playback window with a slider bar. You can play the file back in near real-time, or work through the file slowly, examining the individual frames.

DVP opens up a preview window with slider bar that you can drag to any frame. Unlike the other two programs, DVP doesn't process first, then preview, it simply walks through the video frame by frame, slowly applying all effects and then moving to the following frame. Also, unlike Media Studio and Premiere, DVP doesn't save the resulting preview file into a temporary file that would enable real-time playback. All previews are non-real-time.

That said, DVP provides virtually instant access to all frames, since you can move the slider bar to any video location. Premiere and Media Studio provide roughly similar functionality by letting you preview only a region.

Both Premiere and Media Studio let you instantly preview any particular frame by clicking on the time line above their respective construction windows. The value of Premiere's instant "preview" is eroded by the fact that it doesn't incorporate most filters, transitions, keying, or special effects, so often you end up looking at a background matte and a big red X advising you certain effects were unrendered, and only running a complete preview ameliorates this situation, allowing you to go back and examine individual frames in all their rendered glory. In contrast, Media Studio takes a bit longer to display a frame but incorporates all time line elements in its instant preview.

Since compression can degrade video quality, previews that comprehend the deteriorating effects of compression are most accurate and therefore most useful. Only Premiere takes this extra step. Strangely, Media Studio requests the compression technology in the preview options box, but not the data rate, which usually has more impact on quality.

Since preview is a frequent step, timing the respective programs when compiling a two-second preview of two clips joined via a wipe transition gives some indication about real-world expectations. The tests reveal that Premiere is almost twice as fast as Media Studio and over three times faster than DVP. Further testing showed this first performance test to be an accurate harbinger, as Premiere proved substantially faster than both programs in virtually all similar tests. --Jan Ozer


Companies Mentioned in This Article

Return to Top

Adobe Systems, Inc.
345 Park Avenue, MSW18
San Jose, CA 95110-2704
408/536-6000; Fax 408/357-4004
http://www.adobe.com[LiveLink]

Asymetrix Corporation
110-110th Avenue NE, Suite 700
Bellevue, WA 98004-5840
206/637-1618; Fax 206/637-5802
http://www.asymetrix.com[LiveLink]

Intel Corporation
2200 Mission College Boulevard
Santa Clara, CA 95052
408/765-8080; Fax 408/765-6187
http://www.intel.com[LiveLink]

Microsoft Corporation
One Microsoft Way
Redmond, WA 98052-6399
800/426-9400; Fax 206/936-7329
http://www.microsoft.com[LiveLink]

Radius, Inc.
215 Moffett Park Drive
Sunnyvale, CA 94089
408/541-6100
Fax 408/541-6150
http://www.radius.com[LiveLink]

Ulead Systems
970 West 190th Street, Suite 520
Torrance, CA 90502
800/858-5321; 310/523-9393; Fax 310/ 523-9399
http://www.ulead.com[LiveLink]

----------------------------------------------------------------

Jan Ozer is a contributing editor for EMedia Professional. President of Norcross, Georgia-based Doceo Publishing, a multimedia title developer and publisher of the Video Compression Sampler series, Ozer consults widely on digital video and is at work on the second edition of his book Video Compression for Multimedia, published by AP Professional.

Comments? Email us at letters@onlineinc.com.


Home Page

Copyright © 1997, Online Inc.[LiveLink] All rights reserved.
info@onlineinc.com
[This site created for best results under Netscape.]