Peter Webster, Northwestern University and Dave Williams, Illinois State University

QuickTime was introduced by Apple Computer, Inc. in January of 1992 as a system-level software technology designed to integrate time-varying information (such as motion and sound) into the basic operations of the computer

This software technology allows the digitization of audio and video data from analog sources and then its compression for storage and decompression for playback on various PCs

It is designed to be used with little or no additional hardware but can also be used with add-on equipment ranging from a few hundred to several thousand dollars.

QuickTime was engineered in three parts: (a) movie toolbox, (b) image compression manager, and (c) a component manager. From the start, it was designed as an open architecture that could be extended by third-parties.

Media supported include: motion video, digital audio, music (MIDI-like code), animation and sprites, still images, and text. These media can be combined and synchronized together and multiple layers of media (such as two or more text layers) are supported. Layers can appear and disappear in time independently. Note: Each medium is often thought of as running in "tracks" but this is somewhat misleading. All these elements are combined into one data structure.

QuickTime is available for both Windows and Macintosh computers and has emerged as the major standard of its kind for personal computers. QuickTime system software is distributed freely, together with support software for capturing and editing media.

Files that are produced are often referred to as "movies" (not to be confused with Macromedia Director files that are also called movies). QuickTime files are easily converted between Windows and Macintosh computers and are often distributed on CD-ROM or over the Internet.

Most multimedia-capable machines now sold for $2-3,000 will have all that you need.

If you own a recent Windows machine that supports multimedia, you have all that you need to play back QT movies. Some Windows machines are now being sold with built-in decompression hardware such as MPEG boards for faster rendering of images, but this is not required. 486 and Pentium models are highly recommended for playback. Monitors and computers that support 16-bit color are recommended, as are external audio speakers. At this time, it is difficult to produce QT movies directly on your Windows machine.

If you own a Macintosh computer and you want to produce QuickTime movies, you may already have video digitization capabilities. Macintosh AV machines and many of the new PCI PowerMacs come with video digitization build in. All of the more recent Macs have audio digitization. For playback, any recent Macintosh will work. 68040 and PowerPC models are highly recommend for production and playback. Monitors and computers that support 16-bit color are recommended, as are external audio speakers.

You can capture video from video devices such as VCRs, camcorders, Hi8 cameras, and laser disc players. S-video or composite connectors are usually supported and the video can be either NTSC or PAL format.

Digital audio can be taken directly from built-in audio CD players or captured from outside sources.

For producing and editing QuickTime movies, 16 megs of RAM is considered minimum. Larger amounts of RAM will allow digitization directly to memory which is ideal, but not necessary. Digitization to hard disk is common and the larger the hard disk the better. A typical 230-500 MB hard drive is fine.

Very little, even to produce movies. QuickTime itself is free. Basic editing can be done with free software like MoviePlayer (see below). More fancy editing can be accomplished with modestly priced titles. Computers come with software for capturing video as part of the digitization capabilities.

For creating text, all you need is a simple word processor. CD audio (16 bit, 44 kHz) and MIDI files can be captured directly into movies using MoviePlayer (see below).

The Music "track" in QuickTime is not exactly MIDI code, but is derived from it. QuickTime editing software like MoviePlayer can convert standard MIDI files into code that can be rendered by MIDI sound sources.

For the Mac, this is done most easily by sending the MIDI-like data to a set of software resources called the QuickTime Musical Instruments. This is a system extension that comes with QuickTime and is free. These software resources comply with 43 of the General MIDI sounds, similar to the sounds in Roland Corporation’s Sound Canvas General MIDI module. (Note: Currently, QuickTime does not send this code through to a MIDI interface for external equipment, but this capability will soon come. )

For Windows machines, QuickTime links with the MIDI driver found on MPC-compliant computers. The MIDI Mapper can be used to route the data to available devices.

Start by turning off all non-essential system resources like networking (e.g. AppleTalk on the Mac) and other system extensions.

Although you can capture both video and audio at the same time, try not listening to the audio DURING the capture process. Also, for best results in capturing video, DO NOT capture both audio and video at the same time. Begin by capturing just the video, then capture the audio in a separate movie and then combine the two using editing programs like MoviePlayer or other more sophisticated editors.

Use the fastest CPU computer you can. Try capturing the initial file directly to RAM if you have enough space to do so. If not, capture to the internal hard disk, never to an external disk unless you have special equipment.

Use the very best original image that you can.

Decide on the smallest physical size for your movie’s image you can live with. The smaller the image, the better the computer’s ability to render the movie.

Right after the original capture, the file that will be on disk or in RAM will be much too large to use and must be compressed. As the compression process begins, make sure that you have plenty of room on the disk to accept the compressed version. Both versions will need to fit on the disk at least until the compression process is done.

This is a HUGE topic and one that occupies the thinking and the experimentation of professional digital video developers all the time. Compression (storage) and decompression (rendering for playback) is at the heart of QuickTime and is what makes the magic really work. Compression and decompression are necessary because even a short clip of untreated video running at acceptable speed, color and frame size can run over 100 MB without audio!

Compression and decompression are handled by software routines called "Codecs" and QuickTime comes with several different kinds depending on the kind video image. QuickTime is flexible so that other companies can add their own codec solutions to QuickTime. The two most often used codecs for motion video are Apple Video and Cinepak. Use these two for experimentation. Be sure to start by saving the original clip WITHOUT compression so that you have a backup with which to experiment.

Try the following experiments with your video clip. Realize that each clip is different and will respond differently. Any motion video capture software will allow you to set four primary options for compression: (a) frame rate, (b) kind of compression routine, (c) quality of image and (d) quality of motion (key frames).

Set the frame rate for compression at the same or some multiple even divisor of the original video frame rate. For instance, if you are capturing NTSC video tape from a VCR, capture at 30 frames per second (fps) if your computer is known to be able to sample this fast. Other recommended rates would be 15 or 10 fps. The latter choices are more realistic, even on today’s fastest Macs and Windows machines that do not contain special hardware like JPEG or MPEG cards.

Apple Video and Cinepak differ in the rate of their compression and decompression. Cinepak takes a very long time to compress a clip, however its decompression for playback is very efficient, especially when the clip is to drawn from a CD-ROM. Use Cinepak if you are not on a time limit in your development process and can afford to experiment. If you are limited in time and still want to experiment (and if you are running video from your hard disk) use Apple Video. There are other very complicated issues here, but these are the over-riding ones. Both routines are the best available at this time for non-hardware supported QuickTime work.

The "quality" slider bar adjusts the amount of compression that is applied to clips. There are two schemes for compression that are used in Apple Video and Cinepak and both schemes are used together in each kind of compression. One scheme is called temporal compression and it eliminates redundant information that exists from frame to frame. The other is spatial compression and it eliminates information within a single frame. The slider bar adjusts both together. If you want to adjust scheme individually, you can do this by holding down the option key while moving the "quality" slider. Do this only if you have a good concept of what tradeoffs you are making, otherwise treat each together. Obviously, the closer to "high" quality you work, the larger the file. Choosing a high quality may not substantially increase the real quality however. It depends greatly on the kind of motion within the clip. We suggest a middle to 75% setting for generally good results.

Key frames should nearly always be used if you need to edit the movie or play the movie backwards. The key frame sets the boundaries for temporal compression. Frames between key frames are treated temporally. Each key frame itself is treated spatially. Set each key frame for the same rate as the frames per second setting. This will ensure at least one key frame per second (e.g., if you are capturing at 15 fps, set the key frame for 15). Experiment with higher rates if needed, especially if there is a lot of movement in the original video.

A sprite toolbox for employing an animation track. Sprites are moving pictures that are themselves animated as they move. The software for developing sprites within QuickTime is not yet generally available to the user.

Improvements for running on the newer PowerPC 604 machines

Better support for QuickTime video conferencing and QuickTime VR.

Improved support for the MPEG codec and for on-board hardware (This probably means that Macs and Windows machines will have on-board hardware for MPEG video in the very near future.)

Ability to open ulaw and WAV sound file formats.

Here are some things to consider beyond what is immediately apparent from the MENU bar.

Short cuts for playing and stopping the movie?

Use of the arrow keys?

Short cuts for copy, pasting, deleting, etc?

Hold the CONTROL key down while clicking on the single step buttons to quickly shuttle around the movie, backwards and forwards.

Experiment with the pull-down menus in the Get Info dialog box. You can see the exact timing of where you are in the movie from the "time" menu. You can see the attributes of each track on the movie, text, music, audio, video, etc.

General Tip: As we've discussed above, pressing the Shift, Option and Option+Shift keys provide different menu items in MoviePlayer. Be sure to explore these differences.

Critical Tip: AFTER EDITING, DON'T FORGET TO DO A "SAVE AS" and select "Make movie self-contained." If you don't do this, you are likely to take the movie to another computer to play it and get an error message telling you part of the movie is missing.