File Formats
Converting document information, created by one application to be used in another application under the same operating system and/or under an alternative operating system can be a daunting problem. And more so when the conversion includes communicating with such external devices as TV tuners, VCRs, still video cameras, video CDs, and audio sources. There are physical limitations to such "multimedia" conversions. For example, a single digitized color image may require 1MB to be represented as a 24-bit RGB image. To display a TV screen's "real-time" motion requires 30 frames per second (fps). To match the full-screen analog performance of a TV, a computer's internal bus would have to process 30 MB per second (for just the video). To overcome this limitation, a computer needs highly integrate digital audio video (DAV) interface and digital signal processor (DSP) chips, usually on an adapterboard plugged into a dedicated local bus slot to handle data transfers. In time, the design of all computers will be affected by multimedia considerations.
Multimedia data compression/decompression (codec) schemes already affect the evolution of text-only applications. Suitably-equipped computers can give voice to text. Text may be annotated with verbal notes. Text can be added to single-image graphics, multi-image animations, and real-time video. Typically, applications take an "object-oriented" approach, treating as equal objects text, graphics, sounds and video images.
Most applications have a unique way of defining and structuring a document. Flexible two-way links let users attach one object to another in various ways within a document. Conversion problems may result from incompatibilities among the many document formats, data compression processes, synchronization and transmission schemes, and file formats. A short list follows. (Note, Filename ". " extensions are in italics.)
Document formats include: MHEG (Multimedia and Hypermedia Experts Group), Hytime (Hypermedia time-based language) and IMA common scripting language.
Compression processes include: CCITT's H.320, Cinepak, Fractals, Intel's Indeo, MPEG-1 and -2, and Wavelets.
Synchronization and transmission schemes include: Apple's Bento, COSE (Common Open Systems Environment systems services, IMA (Interactive Multimedia Association) system services, MPEG (Moving Picture Experts Group) system services, Open Media Framework, and SMPTE (Society of Motion Picture and Television Engineers) Digital Image Architecture.
File formats for Animation include: Autodesk (.FLC/.FLI) and MacOS (PICS).
File formats for Digital audio include: Amiga (.SVX), Creative Labs (.VOC), MacOS (. snd ), Pulse-code modulation (.PCM), and Adaptive (PCM), Sun and NeXt (.AU), and Windows (.WAV).
File formats for Digital video include: Amiga (.AWM), Apple QuickTime (.MooV), Grasp Pictor (.PIC), Intel (.VSS), Macromedia (.MMM), Persuasion (.PER), and Video for Windows (.AVI).
File formats for Graphics include: Compuserve (.GIF), Encapsulated Postscript (.EPS), Intel (.DCX), MacOS (.PICT), Windows Bitmap (.BMP), and Windows graphics metafile (.CGM).
There are many utilities available for "converting" or "translating" the data-format of a specific application's "document" files so that the text, graphics, sounds, video, or animation in them can be used by other applications. The format specifications, that start on the next page, should be useful in choosing and using such utilities.
You may just want to view a document, play a movie or listen to some music--without converting them to an editable format. For this purpose, there are Viewers and Players. (Some of them also let you edit files.) Among them, some are more capable of handling a specific file format than others with the same ability. There are shareware viewers and players available for many formats that may not yet be handled by one of the commercial utilities.
For some viewing or playing, you must have the hardware capabilities; such as a 24-bit videoboard, 16MB of RAM or more, or a soundboard, that is capable of dealing the specific file format. This is of particular necessity when viewing and playing files accessed via the Internet or bulletinboard service. Your satisfaction, in using these utilities may also be determined by how fast you can access a document, render an image onscreen and/or output a sound or picture, and so on. If this is true for you, then only the currently fastest processor and system bus, data storage access and transfers, video and sound subsystems, modem and communications links will satisfy you.
Our publication: PC Whats The Problem? includes responses to file damage, format conversion and security problems.
References are samples only. Each one is presented in greater detail in the
Technical Research Assistant for 2001
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