Multimedia Development Streamlining Cross Platform

Transcription

1 Multimedia Development Streamlining Cross Platform The process of cross platform multimedia development has become much simpler over the last few years. Increasing standardization, the development of sophisticated media manipulation software, and the emergence of authoring packages designed for cross platform operation have been important contributors to this trend. Riding on the crest of this wave has been the emergence of the World Wide Web (WWW) as a viable option for true multimedia delivery, although the more traditional tools still have the edge in terms of stability and interactivity. Today there are more multimedia delivery options than ever before to choose from. This paper will attempt to put these options into a perspective, highlight some particular technical pitfalls for the unwary, and will conclude with an extensive list of online information sources to assist the reader towards creating a successful cross-platform multimedia project. The first section "General Considerations" is aimed at the non-technical reader, including those without programming or multimedia authoring experience, "Technical Considerations" is aimed at multimedia programmers/authors, while the concluding appendix contains hypertext references to online information sources. General Considerations The first and most important considerations in any multimedia project, but especially in cross platform development, are (i) What is the objective of the project? and, (ii) Who are the intended audience for the final product? The intended audience will determine amongst other things the minimum hardware requirements of the delivery computers, and this in turn will determine a host of other technical production parameters. The purpose of the project will impose certain requirements on the features that must be delivered by the software, including responsiveness/speed, complexity of interactivity, animation, graphics, and performance of digital video and audio. Other requirements will be known only to the project creator, such as the level of technical ability or aptitude and skill available amongst the project team members, availability of technical support and training, project size, budget, and timelines for completion. Other important considerations include whether control is required over the distribution of the final project (this could be for copyright reasons). Fairly early on it is important to decide what constitutes acceptable delivery standards for your project: if you limit the delivery platform to the lowest end, you will be accepting severe performance limitations (see appendix 1). Conversely, if a higher standard is set, your project can be optimized to take advantage of the resources available. No matter which software package is used, you should test your project on each platform frequently during development. Make sure your software runs on the minimum hardware platform you have decided on. In general, projects whose requirements are mainly text and graphics based, and whose audience are online (e.g. students at a University) may be well served by creating a WWW site. Projects that require access to large data files (e.g. large Quicktime movies, or lots of high resolution images) with a higher degree of customized interactivity are often better suited to a CD-ROM based solution. For more in depth discussion of specific authoring environments, please refer to the references section at the conclusion of this document. Protecting your investment in media preparation Most multimedia projects require extensive media preparation, nearly always the time spent in preparing media for use vastly exceeds the time spent in actually assembling the program. Additionally, in the case of cross platform development, you may have files on both platforms that require backup, along with files in multiple formats. The basics of project management are

2 important here: establish a reliable and regular backup system and make sure that your files are backed up regularly. Do not rely on any one piece of media to protect your data: e.g. if the only copy of a certain file is on a DAT tape, there should be at least two copies of that tape. Make sure that your backup copies of data are NOT stored with the originals, they should preferably be stored in a different building (off-site backup). Make sure whatever backup system you use allows you to easily search for a file, chances are, when you need it you'll need it in a rush. For backup software, I can recommend Retrospect and Retrospect Remote on the Mac. If you use removable media, such as magneto optical drives or Jazz/Zip drives, or if you are using CD-R, you may find it helpful to obtain a file indexing application such as Virtual Disk. For cross platform development you may wish to check when purchasing peripheral devices whether they will run on both platforms. If you are developing on the Mac, or under Windows 95 on the PC, use long, descriptive file names for files, to aid in clarity. I have found it useful to establish naming conventions that shows the format of the file in the name. Using this system, when you are looking at file listings is easy to identify not only what the image is, but what format it is in, for example, an indexed image might have "idx" in the name, or a flattened movie "-f". When files are ready to be used in the project (and these will be a small subset of all the files you create) sad as it may seem, you are probably best to religiously limit naming of files to 8 characters plus a 3 character extension. Use numbers and letters, no special characters, and do not make differentiation between lower and upper case. Observing these rules will save you a lot of wasted time when it comes to shifting the files to the PC, or pressing an ISO CD-ROM (see below, Technical Topics, CD-ROM). One of the early decisions to be made is how you intend to distribute your project. If you decide to use the WWW, you will need to set up access to a web site on which to put your pages up. If your project is at a University or business with an intranet, consider whether you wish to make media files available via locally mounted volumes (through AppleShare or Novell (PC), instead of linking to a document or file via " use "file://". The user will have to ensure that the necessary volume is mounted, in the case of lab computers, this may happen automatically when the student logs in. Advantages of this system include speed of access (you are not relying on a web server to dish out data), and copyright control (you can know with certainty that files can only be accessed by people on your intranet). In a recent project for an accountancy course here at Otago we have using this system with great success... ( Another similar option to consider is placing these local files on a CD-ROM, you could then distribute the files on a cross-platform CD to users (e.g. students) while making additional material available on-line through a web server... (Omari, Arshad and Brogan, Mark; New Directions in courseware delivery:multimedia, CDROM and the Internet. (Use of HTML as a portable document format for multimedia delivery via CD-ROM, discussion of tools used, and problems encountered, the latter being slightly out of date since the advent of Netscape 3). These "hybrid" solutions have many advantages: large digital files can be made available without cost of downloading time/expense, graphics load quickly, yet content material can be kept up to date (through web). When using the WWW, be aware of the ways you can use helper applications to enhance your project. We have used screen recording software (such as Lotus ScreenCam on the PC, or CameraMan on the Mac) to record screen activity inside software. Using this software, help files on mastering tasks in programs like SPSS or Excel were created. These files were linked to web pages to provide simple on-line assistance to students learning these packages. We have also used Adobe Acrobat to load PDF document files in the same way, making examination papers and extracts from texts available online. An advantage of the Acrobat being that we can restrict printing and copy/pasting of the documents, thus protecting copyright, these files are also only available through the intranet. As PDF is a cross-platform format, these files are readable from the Mac, too. Netscape now comes with a QuickTime plugin on PCs and Macs (a VR plugin is also available), you may also download Shockwave plugin to access Macromedia Director files on web sites from inside Netscape. Other options include Java for interactivity, easy-to-use web authoring packages are now available that open up Java authoring to non-programmers. Taking

3 advantage of these extensions to Netscape, you can enhance the multimedia content of your Web pages. Technical Topics CD-ROM CD-ROM drives vary in terms of access speeds. The most common are double speed drives (300 KB/sec), while most new multimedia computers have quad speed drives (600 KB/sec). Be aware that CD-ROMs have slow seek times when locating files. In general therefore, you should avoid doing things in your program that require accessing different files simultaneously (e.g. changing cards while playing a movie) or exceed the data throughput of the drive. Also, when scripting, be aware that your media is locked: changes made by the user may disappear when the card/frame is left. Store user data in globals and test that your program works correctly when in read-only mode. If you are using Toast CD to prepare a cross-platform CD-ROM (which I highly recommend you do) you may wish to select Toast's Hybrid CD-ROM format. Toast's Hybrid format is an ISO 9660 with the additional Mac information... (High Sierra format information), which will allow normal Macintosh file naming, icons, and folders when the disk is viewed on a Macintosh computer. A system of aliasing allows each file to have two names, one visible on the PC (ISO name), and another on the Mac, and allows Macintosh files to have resource forks (these are stored as separate files on the ISO disk). It is also possible to hide files from either platform, so users only see files relating to their computer. Avoid the use of the resource fork on the Mac, as PC files do not have one, instead either import media directly into the application or place in a resource folder in the same file as your project and link media. If you are writing to CD-ROM, and the authoring application you are using supports embedded media do so, this will cut down on seek time while the CD-ROM looks for data. Depending on the approach you take, you may need to write a function to return the folder location. Video: The industry standard for cross platform video delivery is QuickTime. The Quicktime extension is pre-installed on all Macintosh computers, while the QuickTime for Windows installer is available from Apple. There is a variety of compression CODEC available in QuickTime. If your project requires full motion, full screen video, and if you are willing to restrict distribution to those computers with hardware assisted playback you may wish to investigate MPEG video, otherwise, you'll probably be limited to one of the lossy compression methods. The best tool available for compressing movies into formats other than MPEG is Movie Cleaner Pro (Mac only). Movie Cleaner will take you through the steps involved in choosing the correct compressor and compression settings for your project, based on your responses to a series of questions, and will then compress your digital video. Movie Cleaner also includes advanced options for experts, including the ability to select palettes and apply custom effects and is an essential tool for anyone involved in compressing QuickTime movies for multimedia. The program will also prompt you intending to deliver cross platform, selecting this option will ensure that control data for the movie is written to the data fork, while other options will restrict data rates for CD-ROM delivery. In the case of Macintosh Quicktime movies prepared in other programs, open the movie in movie player (or a wide variety of other QuickTime applications) and select "Save As", choose option "Playable on non-macintosh computers" (this will "flatten" the movie to a singe fork), and "Make movie self contained" (file dependencies are not supported on the PC). You may need to rename the movie, to ensure that the name is PC compatible, the three character extension should

4 be ".mov". A variety of applications exist to convert Windows AVI movies to QuickTime and visa versa. If you intend to distribute QuickTime or QuickTime for Windows with your software you must obtain a license. Graphics: First, decide on screen size (for most multimedia projects today this will be 640 by 480 pixels) and the color bit depth. If your project requires photographic images, or the digitization of slides, for the highest quality I recommend the use of Kodak PhotoCD. If you intend to deliver your project to the widest range of computers, limit colors to 256 colours/8 bit. When displaying on a computer in 8 bit mode the computer's color palette will be set to that of the image. If your program contains a number of images, you may experience undesired effects as the program transitions from one color palette to another. In addition, in certain packages such as Macromedia Director, visual effects may not work correctly or at all. Certain colors in the palette should be reserved for system use, these are used to correctly display dialog boxes, the menubar and other program windows, such as the finder. Numbers reserved for these purposes are 1-10 and 247 to 256, leaving a total of 235 colors available for your project. Of course, if you are not showing dialog boxes, menubars and have hidden other applications you may choose to ignore this restriction. Showing a black full screen window behind your project (to hide other windows) will stop users from seeing the effect of the palette change on other windows on the screen, which can be distracting. Users with monitors set to greater that 256 colors will not notice these problems, as image palettes will be a subset of available colors in the system palette. Some applications, such as Director, will import images at the resolution the monitor is set to, check your monitor bit depth. If your resolution is set to high, image palettes will not be created, and you will not become aware of the problems referred to until you try to convert your project to the PC, at which point images will revert to 8 bit display with undesired effect and consequent introduction of transition/palette problems will occur. There are two solutions to this problem: fade to a black screen when transitioning between palettes, or prepare a "super palette" that contains all the colors used by all the images in your program. There are several ways to prepare a super palette, the most labor intensive way (but one which doesn't require you to purchase additional software) is to open a graphics program such as Adobe PhotoShop, paste all the images you need to display in your program into one big image, and select "Indexed Color" from the Image menu. Photoshop will create an optimized palette of the best 256 colors to represent the image. However, for larger projects, purchase DeBabelizer, which can examine a folder of images, create an optimized super palette, and convert the images to any desired format. DeBabelizer also includes a wide range of other automatic image conversion features and QuickTime movie manipulation options that make it an invaluable tool for the cross-platform developer Text Text often does not translate accurately between Macs and PCs. Fortunately, most cross platform authoring environments provide a degree of automatic font translation, so the program will know if "New York" is used on the Mac to use "Roman" on the PC. You cannot rely, however, on users having all fonts available, if it is important, check in software for the presence of the fonts you require and alert the user if a needed font is missing. You may need to do some experimentation to determine which TrueType fonts, in which sizes give identical results on each platform. If copyright provisions permit, distribute the essential fonts with the project, especially if these are non-standard. Tools exist for font manipulation, such as Macromedia Fontographer, however this is an art in itself. Automatic font translation features in most authoring packages are not perfect, are a few simple rules will help to avoid major problems. The first major difference between Macs and PC

5 is that PCs require line feed characters. Avoid the use of special characters, these include ellipse (use three dots), curly quotes "" and '' (use plain quotes), < /> (use >= /<=), bullet use *, or any other special character obtained via an option or shift key, e.g. degree symbol. In addition, realize that most font attributes, such as kerning and spacing, will vary. If you are relying on a particular appearance for aesthetic effect, and the text is does not change, consider pasting the text as a graphic. Working with foreign languages imposes special considerations. In the case of Roman dialects, your main problem will be accented characters such as è, ü, or ç etc. When moving from one platform to another these will not translate correctly. If you have a number of files to convert you may need to use a word processor or commercial utility to assist in the conversion process. For small jobs, you can use the "Character Map" program to determine the correct replacement character on the PC. For scripters, another simple solution is to write a search/replace handler which automatically replaces the special character. If you are testing user input, be aware that many programs will not recognize the difference between the accented and unaccented character : you may need to write an xcmd or dll in these situations. If you intend to work with two-byte languages, such as Chinese or Japanese, the problems are different again. You must decide whether your intended users will have native language versions of the operating system available, or (in the case of Apple) whether they will have the appropriate WorldScript language kits installed. You must ensure that your delivery software can handle two-byte characters, some packages come in localized versions for the particular country (documentation and menus will be in target language), these are available from specialist distributors. Another option is to either include the necessary fonts with the program (you'll need to license them), or present all characters as bit maps. Excellent publications are available that cover this subject in detail. Audio The simplest way to handle audio is to digitize your audio files as QuickTime movies. Alternatively, digitize as AIFF and convert to WAV format for PCs using a utility such SoundApp. The best sound editing tool on the Mac, for multimedia work, is Macromedia SoundEdit16, which provides format conversion, QuickTime support, and a variety of DSP filters, including normalization. Higher level products are available from DigiDesign. I recommend digitizing at 16 bit, Hz ( khz) or higher. Whatever format you choose, make sure that it is supported on both platforms.

6 (Standards are in a constant state of evolution) Appendix: Platform standards Low end MMPC: 386 PC or 030 Macintosh computer 4Mb DRAM 8 bit color (256) display, 14 inch monitor 640*480 pixels 8 bit audio (not all PCs have sound support) Internet: 14.4b modem access Average MMPC: 486/DX66 PC Slow 040 Macintosh computer, e.g. 660AV or LC 575 or slow Macintosh PowerPC, such as 6100/60 8Mb DRAM 2X CD-ROM 16 bit color (thousands) display,14 inch monitor 640*480 pixels 16 bit audio (Sound Blaster on PC, Quadra or AV Macintosh built-in sound) Internet 28.8 modem Higher end MMPC: Pentium PC (100Mz or faster) PowerPC Macintosh (100Mz or faster e.g. 7100) 16Mb or higher DRAM 24 bit ("millions") colors, 15 inch or larger monitor 16 bit audio 4x CD-ROM 28.8 modem (or faster e.g. ISDN or direct IP through network connection) Software Reviews Comparison of presentation packages (Persuasion, PowerPoint), discusses cross-platform portability issues: Levitt, Jason; Comparative Review: A new look at Multimedia Includes link to discussion of publishing/subscribing (Mac) and object linking (OLE): Data Sharing Made Easy, Windows, Mac provide importing facilities, Listing of 50+ authoring environments for multimedia, on Mac and PC, with links to homepages for each company: Multimedia software and hardware site. Good overview of the issues in areas ranging from AV digitizing to software, computer hardware and graphics: Introduction to authoring systems, discussion of metaphors used, selection of appropriate authoring system for specific tasks: Siglar, Jami; Multimedia Authoring Systems FAQ Version 1.4.3, Magazine-style multimedia developers site, with good discussion of wide range of technical and general issues, interviews, etc: Macromedia products (Authorware, Director, Shockwave, SoundEdit16, Fontographer, etc: Technical issues Windows technical information:

7 Check out the Windows developer's site: For Frequently asked questions, try Macintosh Development Apple Mailing Lists, subscriptions: A particularly good place to visit is the survival guides section of Apple Media Program's WWW site. Topics covered include Shockwave, Cross platform multimedia, Desktop audio, interface design, etc: Video Compression QuickTime For developer information, licensing, technical questions, and the Apple Media Program, see QuickTime FAQ: QuickTime Cross-platform page: MPEG Basic review of the standards and discussion of the latest compression hardware (up to $25,000): Cinepak Possibly the most popular multimedia video compressor: Intel Indeo The home page for Intel's Indeo video compressor. Download the latest version for Mac or PC. There are a variety of documents, ranging from the Indeo FAQ and troubleshooting pages, through to more in-depth articles: There is also a special page devoted to cross platform development with Indeo: Indeo and Cinepak, data rates on various computers compared: Windows-based video compression: "Video Compression for Multimedia, a 400 page book, teaches you techniques to capture, edit, and compress digital video under Video for Windows. An accompanying CD-ROM illustrates the products, technologies, and techniques outlined in the text." Ozer,Jan Video Compression for Multimedia, Academic Press. Video Post Processor and Batch compressors: Batch compressor for Video for Windows, see: The batch compressor for Macintosh is Media Cleaner Pro, an essential piece of software, available in a free demo version, plus full version (that allows batch processing, and is PPC native) a must purchase, see: Image related: DeBabelizer The Graphics Processing Toolbox. A must have for cross platform multimedia producers, allows conversion of images between almost any format you can imagine, it is scriptable, does batch processing, supports Photoshop plugins, and can produce image "superpalettes" (CLUTS), manipulates QuickTime movie palettes: IMA Audio Compression Everything you ever wanted to know about cross platform development using QuickTime and IMA audio compression: Graphic Utility FAQ Find a link to the latest image version of any popular image utility (most platforms): File Formats FAQ Multi-lingual For information on Macintosh Worldscript language kits: Japanese: Internationalization:

8 CD-ROM The industry standard package for pressing cross platform CD-ROMs (Mac only) is Astarte's Toast CD-ROM. See: Installation builders Installer VISE (v4) from Mindvision is the best available Macintosh installer. It comes in a full and "lite" (v 3.5) versions, with the latter being available for free use by "shareware" authors: Rodney Tamblyn, rodney@stonebow.otago.ac.nz,