A movie is usually made up of a sequence of photographic images that are moved quickly past the human eye, so as to create an illusion of a moving image. Made-man pictures, often generated by a computer, can be formed into a similar sequence so as to produce animation.
Older computers aren’t ideal for movies and can only accommodate reduced-size pictures at a low frame rate. Fortunately, modern machines can handle full-motion video (FMV), providing results similar to a domestic video system, although not quite broadcast quality.
One of the most popular movie presentation mechanisms is known as QuickTime, which can be used on both Mac OS and Windows-based computers. The applications supported by with this package in the Mac OS are QuickTime Player (or MoviePlayer in older systems), for playing movies and sounds, and Preview (or PictureViewer in older systems), for looking at still images that may be compressed using QuickTime technology.
When playing a movie file in QuickTime Player, the QuickTime software tries to play successive frames at the intended frame rate. If the computer can’t cope, some data may be skipped to maintain timing, which can result in jerky images or sound break-up. The actual performance is dependant on your processor speed, the drive speed, the nature of the movie (image size, colour depth and frame rate), the presence of a sound track and the type of compression.
The following shortcuts apply to QuickTime Player in the Classic Mac OS. Some are also effective in a Web browser, when using the QuickTime Plugin file, or in other applications.
|Play forwards||Return, Space or ⌘-⇢|
|Stop||Return, Space, ⌘-., ⇠ or ⇢|
|Move one frame back or forwards||⇠ or ⇢|
|Pause on or off||Return or Space|
|Move to start or end of section||Option-⇠ or Option-⇢|
|Turn sound volume up or down||⇡ or ⇣|
|Set sound volume to maximum or mute||Option-⇡ or Option-⇣|
|Set sound volume beyond maximum||Shift-⇡|
The following tricks can also be used:-
|Double-clicking on movie image||Starts or stops movie|
|Pressing Option or Shift in menu||Extra options appear in Edit and File menus|
|Dragging progress pointer||Moves to a new position in movie|
|Pressing Shift while dragging pointer||Selects a portion of movie|
|Pressing Shift and resizing window||Resizes image non-proportionally|
|Pressing Option and resizing window||Resizes image in even multiples of size|
The Favorites area can be used for online movies or ‘local’ movies. Items can be repositioned as required (dragging onto an existing item removes the original) and unwanted items can be dragged to the Trash. You can also drag a movie onto the desktop to create a shortcut file for later viewing. Even a text file can be dragged onto the area and played as a movie!
A movie editing application lets you assemble video and sound material into a complete movie, for which you’ll need a computer with a FireWire port and a Digital Video (DV) camcorder.
First, you must get your video material from the camcorder to the computer. Simply connect the latter’s DV connection, sometimes known as an iLINK port, to a spare FireWire port on your computer. This connection conveys video and sound material to the computer, and in some instances in the other direction as well. The iMovie application can also control the transport of your camcorder via FireWire, assuming your particular type of camcorder supports this feature.
iMovie handles standard-quality video data as an uncompressed DV Stream, requiring at least 210 MB of disk space for every minute of recorded video. This means that you’ll need 10 GB just to record 45 minutes of material. The following table shows the data rates for the full range of DV formats:-
|Format||Coding||Data Rate (Mbit/s)||Notes|
|DV/DVPRO||DV 4:1:1||25||Standard Quality|
|DVPRO50 *||DV 4:2:2||50||-|
|DVCPRO HD *||DV-HD||100||High Definition (HD)|
Handling DV data isn’t too difficult for a computer, assuming your machine has sufficient disk space, the disk isn’t fragmented and the machine has a fast processor.
Your final video production can be transferred onto DVD by using Apple’s iDVD application, which is also supplied with modern Mac OS computers. It should be noted, however, that the original version of iDVD can only create DVDs of up to one hour’s duration while iDVD 2 can record up to 90 minutes. If you need to record even longer DVDs you’ll need Apple’s DVD Studio Pro, which uses variable bit rate (VBR) encoding to extend the maximum recording time to two hours.
To save disk space, or to distribute your work, you can export movies as QuickTime files. Although iMovie may default to using the codec known as H.263, you’ll get better results using Sorenson Video or Sorenson Video 3 compression, especially if your material is destined for the Internet.
Movies designed for a CD-ROM should be no larger than
320 × 240 pixels, or even
240 × 180 pixels if your customers are likely to use an older CD-ROM drive. The following settings can be used in the Video section of the panel that appears under Options in the Export dialogue:-
while in the Sound part you can use something like this:-
A movie for the World Wide Web should be kept to
192 × 144 pixels, usually with the following Video settings:-
and these Sound settings:-
Video material in the form of DV data is ideal for editing. Unfortunately, movies are often supplied in alternative formats, most commonly as an analogue video or component video signal. Before editing, such material must be converted into digital form using a process known as digitising.
Your computer must have a suitable video capture card or video input adaptor, the latter connected via a FireWire port or USB port on your machine. You’ll also need suitable software to convert the signal into a QuickTime movie, MPEG movie or DV recording.
If your hardware has component video, select Component Video in the Video settings window when exporting from a QuickTime application. If your audio material is, for example, in 16-bit form, sampled at 44.1 kHz, you should also use matching settings in the Audio window. This avoids time-consuming computations for colour and bit rate conversions.
The following list describes some of the more common movie formats, complete with filename extensions, shown in order of preference, and Classic Mac OS type codes. Those shown with a QuickTime icon can be opened using the applications in the QuickTime package.
The most common formats found on the Mac OS are:-
This standard kind of movie file can be played by any application that supports QuickTime, assuming that the QuickTime software is installed on your computer.
Some applications add a preview image or a custom icon based on the first image. You can also add a preview in the Classic Mac OS by clicking on Create in the standard file Open dialogue. Custom icons are useful for identifying documents in the Finder or in file dialogues.
.m15for 15 frames/second (frm/s) or
.m75for 75 frm/s.
This compressed format can be played using any suitable application.
A newer standard, devised for conveying both audio and video material, and especially suitable for real-time streaming over the Internet. Such files can be read using QuickTime 6.
Contains a high-quality movie, as produced by a Digital Video (DV) camera.
This vector animation format, more accurately known as a Flash media file, was developed by Macromedia for sending real-time images over the Internet. Such documents can be created in applications such as Flash (Macromedia) or LiveMotion (Adobe) and played back in QuickTime.
Flash files are popular on the Web because the files are small, usually containing vector graphics that can be scaled without any loss of quality. However, such documents can be demanding on the computer, even though QuickTime can play multiple media types simultaneously. For this reason, the content of Flash material should be designed to reduce the load on a recipient’s machine. For example, a complex Flash animation should be stopped whenever a video is played.
A total of 16,000 frames are allowed in a movie, which means that a video running at 8 frm/s can last for up to 33 minutes. If you exceed this maximum, Macromedia’s Flash Player comes to a stop at this point. In addition, a movie’s content shouldn’t exceed the 50 MB limit of Flash Player’s memory.
The following data rate combinations are often used to suit various Internet connection speeds:-
|Content||Connection (kbit/s)||Audio (kbit/s)||Video (kbit/s)|
|Video and audio||28.8||8||12|
|Banner ad video and audio||28.8||8||12|
|Video and audio||56||8||32|
|Banner ad video and audio||56||16||24|
|Video and audio||128||16||94|
|Video and audio||356||24||218|
|Video and audio||384||40||324|
|Video and audio||512||40||452|
Other formats include:-
As the name indicates, this kind of file is used for animations on an Amiga computer.
Although this is the standard format for still images on the Internet, the GIF 89a variation of this kind of file can also accommodate animations and image transparency.
.ani, .flm, .ic1, .ic2, .ic3 See below
The following animation formats are used on the Atari ST computer:-
|Format||Extension||Mac OS Type|
A special file format derived from Shockwave Flash and designed for real-time video streaming.
Also known as an Autodesk Animator File file, as used for animations in Windows.
A sequence of Adobe Illustrator image files that together form a complete animation.
A sequence of standard graphics files that form an animation. QuickTime can create these using BMP, JPEG, MacPaint, Photoshop, PICT, PNG, QuickTime Image, SGI, TGA or TIFF files.
An animation sequence, as used in Director and similar applications.
A special format devised by RealNetworks for sending movies in real time over the Internet. Related files, known as RealAudio, RealPix and RealText, are used for sound, pictures and text. All of these documents can be viewed using a special application called RealPlayer (RealNetworks).
This kind of file, produced by cameras that record directly onto DVD, isn’t acceptable to Apple’s iMovie application, although you can use OpenShiva, available from http://openshiva.sourceforge.net, to convert such files into MPEG-4 documents.
AVI movies are used within the Video for Windows (VfW) environment. Although the latter system competes with QuickTime, you can also open these files using QuickTime Player.
A modern Microsoft format used for streaming movies over the Internet.
MacWorld magazine (UK), IDG Communications, 2002-2004
©Ray White 2004.