If you're a video professional who uses Adobe After Effects, at one time or another you've probably longed for the power of a high-end compositing system such as Discreet's Inferno or Flame. Combustion 2, Discreet's first major upgrade to its low-end compositing and rotoscoping system for video and film, should ease some of that longing.

Although Combustion is Discreet's entry-level product, it's an incredibly powerful tool built around the same technology as the company's higher-end packages. At $4,995, Combustion costs nearly twice as much as its chief competitors, Adobe After Effects and Pinnacle's Commotion, but it offers color-correction and painting features far beyond those of lower-priced packages. With version 2, Discreet has added new text and particle-generation features, which make the package even more enticing. And because it can exchange data with Discreet's high-end systems, Combustion 2 can serve as a great low-cost additional workstation for post houses that already have Flame, Flint, or Inferno.

No Windows, No Menus

With Combustion, Discreet eschews almost all of the Mac's interface standards in favor of a derivation of the interface it uses in its higher-end compositors. The result is an extraordinary working environment that runs in either OS 9 or OS X. Once you get used to Combustion's interface, it's hard to go back to other compositing programs.

Combustion has no windows. The entire screen (below the menu bar) is filled with dark gray, to ease color perception. The top half shows your video (or several different views of your video), and the bottom half is a well-organized collection of context-sensitive buttons and tabbed palettes.

There's more that makes Combustion's interface so inviting. First, all functions are context-sensitive--that is, the program displays only tools and options relevant to your current action. While other software companies have tried to create similar environments, Discreet has succeeded--Combustion's elegant interface design never makes you feel cut off from the rest of your tools.

Second (and as in After Effects), all buttons and fields are scrubbable, so you can move your mouse back and forth over a control or field to change its value and watch the screen update in real time. This is an outstanding feature for making changes to a single axis of rotation or position.

In general, Combustion's interface is striking for how little mousing you have to do--the right control always seems to be where you need it.

The only downside to such a different interface is that it can take a day or two to recognize the visual cues that help you understand the organization and relationships of features, but once you do, other compositing packages will seem cumbersome and overly complex.

Compositing and Painting

Combustion can import all major video and graphics formats, and it provides as many as 16 bits per color channel, making it suitable for film work. Like most compositing programs, Combustion separates a project into layers. Each layer in turn can hold video clips, still images, painting information, and other layers. And by providing a workspace palette in the bottom of the screen, the program makes it easy to manage layers.

Combustion allows for both 2-D and 3-D compositing, letting you position objects in true 3-D space and giving you full control over reflections and shadows.

The program also includes the same powerful keying technology as Discreet's higher-end apps, as well as sophisticated vector masking tools that allow for the creation of complex gradient masks.

It also includes a vector paint facility, with shapes, brushes, Bézier tools, and more, and all shapes and paint strokes remain fully editable. Combustion takes a different approach to cloning (a staple function of rotoscoping and compositing). Instead of the single, brush-like cloning tool found in most painting programs, Combustion has many--any shape can be a cloner. For example, you can draw a vector shape and tell Combustion to clone its contents from somewhere else in your image (or from an entirely different frame).

In Combustion, you perform all editing operations by applying the appropriate type of operator to your media. For example, when you want to paint into a piece of video, you apply a paint operator to that clip. In the workspace window, you can see each operator attached to its piece of video. Combustion applies all of the operators on-the-fly when it renders its images to the screen. Because all functions--color correcting, painting, effects filters, character generation, making selections--are applied as operators, you can easily deactivate, remove, edit, or reorder any of the actions that you've performed on your media. This is incredibly powerful and provides tremendous creative freedom.

Color Correction and Motion Tracking

Discreet has also included its high-end color-correction and motion-tracking tools in Combustion. The motion tracker is first-rate, delivering rock-solid image stabilization, as well as motion tracks with subpixel accuracy. And although Combustion allows you to import or export motion-tracking data to a file for later use, we'd prefer a more convenient mechanism for easily storing data within the project file, à la Commotion's Motion Tracking palette.

Combustion's color-correction tools offer all the controls you'd expect to find in an image-editing program, as well as excellent color matching--ideal when you need to match colors between layers.

Two major additions to version 2 are new text features, which make Combustion just about the best character-generating app available for the Mac, and an amazing particle-generation system that allows for quick and easy rendering of everything from fire and smoke to explosions and pixie dust.

Finally, Combustion renders at very high speeds (though your performance will depend on your RAM capacity and OpenGL card), and Discreet generously includes network-rendering software with the package.

Macworld's Buying Advice

If you create composites or perform rotoscoping for a living, Combustion is well worth the investment. Although other, lower-priced programs provide some of Combustion's functionality, its excellent interface and professional-caliber features make it a pleasure to use. You'll have to rethink some of your work habits, but you'll be glad you did.