Screen Machine II brings video capabilities to NEXTSTEP PCs

by Lee Sherman

Now that NEXTSTEP runs on industry-standard PC hardware, users can benefit from the many low-cost multimedia boards becoming available. Screen Machine II is the latest generation of a video-capture board from Fast Electronic GmbH that has become popular in Europe for providing real-time video-digitizing and video-in-a-window capabilities on a single add-in board.

The hardware is identical to that provided for any PC, but the NEXTSTEP version comes with specialized software for displaying video in a window, frame-grabbing, and controlling an optional television tuner. Screen Machine II digitizes images in either 24-bit true- color or grayscale mode and can display live video in any size, and at any position, on a VGA monitor.

Designed to provide a complete video solution for NEXTSTEP PCs, Screen Machine II is notable for duplicating much of the functionality left behind with the demise of the NeXTdimension hardware but don't expect to find the same level of integration. In developing the board, Fast had to contend with the limited bandwidth available for transferring live video over a PC bus. A compromise was reached by letting the Screen Machine itself perform all processing of the video signal and then overlaying it onto the monitor signal. Unfortunately, this prevents cutting and pasting video into other applications.

In order to allow window controls for miniaturization, closing, and resizing to work, the video overlay is mapped to a NEXTSTEP window. Since the video isn't actually playing back in a true NEXT-STEP window, other on-screen graphics, such as menus and inspector panels, can interfere with it, causing problems with the screen display.

Making the connection We installed the Screen Machine II in a Lucky-Goldstar '486 PC that met the requirements for NEXT-STEP. Once the card is installed, you replace the computer's cover and connect it to a video source. Screen Machine can accept either composite or S-VHS video input, meaning it will work with nearly any video source, including camcorders, video recorders, laserdisc players, S-video, Video 8, U-Matic, and still-video equipment in any standard (PAL, NTSC, and SECAM).

Screen Machine II takes up one 16-bit ISA or EISA slot and connects directly to a VGA card with a standard feature connector (audio requires a separate slot). No special configuration was required to get the Screen Machine to operate no small achievement, given the problems of combining incompatible video signals on standard PCs.

Because the card requires a loadable kernel, it is necessary to use the UNIX command line to install the driver software and add a line to your /etc/-kern_loader.conf file if you want it to load automatically when you start up the software. Fast is planning to use the NeXT DriverKit to get around this in a future release.

With a VGA display, you can grab images and monitor the video signal in real time at resolutions of 640 by 480, 800 by 600, and 1024 by 768 the higher resolution is unique among video overlay cards. Built-in digital filtering helps clean up noisy signals, resulting in a high-quality image, even when resized to your monitor's full screen size. Captured video frames are stored in a proprietary YUV format that Fast calls FLM but can be converted to TIFF for use in other applications. You can apply either LZW or JPEG compression to individual frames, but it isn't possible to capture video sequences due to the lack of hardware compression.

On-screen controls let you ad-just the brightness, contrast, saturation and hue of the video signal.

Some limited but fun effects can be applied to the incoming video while it is playing, such as bouncing the video image across the screen, and inverting or flipping it upside down.

Screen Machine II ships with separate applications for controlling the TV tuner, grabbing sequences, capturing single frames, and playing back video in a resizable window. You also can capture closed-captioning information and convert it to an ASCII file.

The software's biggest drawback is its lack of support for digital video sequences. You can capture a series of sequential frames to disk as TIFF files, but these can be animated only if you have software such as Xanthus CraftMan, which lets you play them back at a high-enough frame rate to simulate video.

Without an established standard (such as QuickTime or Video for Windows) for recording, storing, and playing back digital video, Screen Machine fails to live up to its full potential. When NEXTIME arrives (sometime in 1994), it is ex-pected to include plug-in support for all current compression/decompression schemes, including those used by QuickTime and Video For Windows. In addition, NEXTIME will be capable of playing QuickTime and AVI (Windows) files directly. Fast already has a piggy-back board in production for the Screen Machine with on-board Indeo hardware compression. If you'd like to add video-capture capabilities to your own NEXT-STEP applications, you can program the board with the API kit. Completely object-oriented, the kit provides an NXLiveVideo view, and compatible classes, objects, and IB palettes.

Screen Machine brings video capabilities back to NEXTSTEP. Now those who want their NeXT TV can have it.

Lee Sherman is a NeXT-WORLD contributing editor.

Screen Machine II

3 1/2 Cubes

Screen Machine II provides high-quality video capture and video-in-a-window capabilities for NEXTSTEP PCs, bringing back much of the functionality of the NeXTdimension. For now, it is most useful for grabbing single frames or watching television on your screen. When NEXTIME arrives, the Screen Machine may turn out to be the best way to make movies for NEXTSTEP.

$1495 Screen Machine II with software

$149 Audio option

$699 TV tuner (includes audio option)

$995 Developer API kit

Fast Electronic U. S., 5 Commonweath Rd., Natick, MA 01760.