Multimedia Technology Ch 6 Text

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Multimedia: During the past few years, developments in computer technology have raised interest in multimedia as a transformational mode of instructional delivery. In contrast to earlier forms of audio-visual technology, the power of computer-based multimedia results from 1) its ability to combine multiple media formats under a single interface and 2) its ability to link objects within those formats in a nonlinear fashion. Effective incorporation of multimedia into the curriculum requires an understanding of the differences between presentation-mode use of the technology by educators and hands-on use by students. The ultimate success of multimedia will require improvements in network technology to facilitate widespread access to source materials. Multimedia is the combination of text, animated graphics, video and sound present’s information in a way that is more interesting and easier to grasp than text alone.

Text media: When a user has a disability, access to learning software may depend entirely on how flexibly that product can deliver its content. Some users may need only to modify the parameters in which media is presented; other users may require entirely different media. Developers who achieve the kind of flexibility that diversity requires will enhance the accessibility of their product. At a minimum, developers should provide text representations for all media types. This baseline will help address access for many users. That said, it should be noted that users with learning disabilities benefit from graphical presentations. For this reason, the practice of providing text-only content as an alternative to inaccessible multimedia content may not be an effective solution for users with cognitive disabilities. Text and the ability to read it are doorways to power and knowledge. Reading and writing are expected and necessary skills within most modern culture. Text delivers the information that has potent meaning. Words and symbols in any form, spoken or written, are the most common system of communication. They deliver the most widely understood meaning to the greatest number of people__accurately and in detail. Because of this, they are vital elements of multimedia menus, navigation systems, and content.

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When text is correctly structured and formatted, it can be the most flexible way to present content. To make distributed online learning accessible, developers of learning platforms must provide a means to render digital text in alternative formats. Specifically, it should be possible to render text as: • Visual information. Text can be displayed on computer screens or other electronic devices (e.g. personal digital assistants, cell phones, e-book readers). • Audio information. Text can be translated into speech using recordings or via synthesized speech provided by a computer. • Tactile information. Text can be displayed on refreshable Braille displays or printed using a Braille embosser.

Common text accessibility problems include: • • • •

Hard-coded fonts that prevent users from changing style, size, color. Text presented with background images or poor contrast colors that hinder readability. Text presented in an image format that screen readers and Braille displays could not transform. Multi-column formats (including some tables) that screen readers cannot process in the correct order.

Content creators or educators may enhance the accessibility of text for all users by following these practices: • • • •

Choose text formats that offer the most accessibility (e.g. XHTML, plain text). Use true text, and not graphical representations of text. Structure the text appropriately, identifying headings and other structural elements. Uses a number of resources that address flexible media delivery are currently available. The W3C's Web Accessibility Initiative provides accessibility guidelines for W3C technologies such as HTML, XML, SMIL, and CSS & SVG. It also provides more general guidelines for web content accessibility, authoring tool accessibility, and user agent accessibility.

W3C Format With the introduction of Synchronized Multimedia Integration Language (SMIL, pronounced smile) earlier this year, Web multimedia creators have a new tool set for building time-based, streaming multimedia presentations that combine audio, video, 2

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images, and text. The proposed SMIL standard defines an XML-based language that allows control over the what, where, and when of media elements in a multimedia presentation with a simple, clear markup language similar to HTML. In a SMIL presentation, all of the media elements -- images, audio clips, video clips, animations, and formatted text -- are referenced from the SMIL file, similar to the way an HTML page references its images, applets, and other elements. A number of advantages come with such an approach to streaming media. First, the plain-text nature of the SMIL file means that it is easy to create, easy to edit, and can even be assembled on the fly by Java servlets or CGI scripts accessing a database. It also allows a very bandwidth-friendly way to do great looking multimedia. Rather than streaming images and text as many redundant frames of encoded video, you can stream the image or text data just once, and display it however, you like. The first commercial SMIL player to arrive on the scene is Real Networks' latest version of RealPlayer, called G2. While the previous versions of RealPlayer played only Real Networks' proprietary audio and video file formats, G2 includes support for many other media types like WAV, AVI, JPEG, MPEG, and others. Real Networks has implemented a large subset of the SMIL 1.0 spec in G2, and intends to support the entire spec. G2 also supports a number of custom XML-based data types that provide additional features for animating text and images and providing interactivity. SMIL authoring offers a new way to assemble and deliver streaming multimedia presentations. Rather than the traditional way of creating a presentation by compiling a set of media into a single distributable file, SMIL lets authors choreograph separate media assets quickly and easily, with tools as simple as a text editor. Perhaps the best feature of SMIL is the ability to generate the code on the fly, as many Web pages are already created, and thereby offer personalized streaming multimedia. It is even possible to build a Web-based interface for allowing users to edit or assemble new multimedia presentations. For those who'd prefer a GUI authoring environment, several vendors have recently announced tools for building SMIL, RealPix, and Real Text presentations within a graphical environment that would look familiar to most multimedia authors. The ability to stream text offers new capabilities, too, in combining low-bit-rate video with crystal-clear text. Real Networks offers a live text stream encoder, which could be used for streaming real-time data of all types, including event information and schedules, stock prices, general announcements, closed-captioning, subtitles, and more. SMIL, while it offers many of the capabilities of existing multimedia environments like QuickTime, is not meant to be a replacement for these technologies. Rather, it is a kind of universal glue for joining all kinds of different formats and types of media in interesting and useful ways. Real Networks intends its G2 RealPlayer to be a universal player. Its architecture allows third-party developers to add renderers for new media types, which is 3

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how support was added for MPEG1, VRML, and MIDI, for example. Over the coming months and years, the maturation of both SMIL and the G2 RealPlayer may offer the most compelling opportunity yet for "convergence" between home entertainment and computer technologies.

Character sets: Knowing that there is a wide selection of characters available in computer and understanding how it can create and use special and custom-made characters will broaden it creative range when to design and build multimedia projects. 1. ASCII Character Set: The American standard code for information interchange (ASCII) is the 7_bit character coding system most commonly used by computer systems in the United States and abroad. ASCII assign a number or value to 128 characters, including both uppercase and lowercase letters, punctuation marks, Arabic numbers, and math symbols. Also included are 32 control characters used for device control messages. 2. Extended Character Set: A byte, which consists of eight bits, is the most commonly used building block for computer processing. ASCII uses only bits to code its 128 characters; the eighth bit of byte is unused. This extra bit allows another 128 characters to be encoded before the byte is used up, and computer systems today use these 128 extra values for extended character set. The extended character set is most commonly filled with ANSI (American national standards institute).this fuller set of 256 characters is also known as the ISO_Latin_1 character set; it is used when programming the text of HTML web pages.

3. Unicode: Unicode focused on 16_bit architecture for multilingual text and character, it can accommodate up to about 65,000 characters and will ultimately include the characters from all known languages and alphabets in the world.HTML allows access to the Unicode characters by numeric reference.

Using text in multimedia 4

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Interacting with a multimedia information system is quite different from interacting with a standard text-based information system. In any such system, the realworld objects, which comprise its domain, are directly represented through their properties and indirectly represented through their relationships to other real-world objects. In text-based systems, however, all properties and relationships are presented in a textual format to the user. In standard relational systems, each real-world object has a unique textual identifier and has properties whose values can be textually presented. Even in object-oriented systems, which allow the representation of more complex properties, such as those, which are set or sequence valued, or those whose values are other objects, information is presented in a textual format. In a multimedia information system, however, there exist representations of objects, which are not textually based. These representations consist of portions of images (static visual representations of objects), videos (dynamic visual representations of objects), and audios (aural representations of objects). When these representations are included in the domain of an information system, they can be used in two distinct fashions: as real-world objects themselves, having properties and participating in relationships, one can treat them as one treats other first-class objects and seek to gain information about them; or, as user-recognizable surrogates for the real-world objects which comprise their content, one can use them in the process of seeking information about the corresponding non-media objects which they represent. Knowing the identities of the various non-media objects, which are represented, by a media object is quite powerful. By seeing or hearing a media object, the user of a multimedia information system can gain information, through his or her own knowledge, concerning the represented non-media objects, which may not be explicitly modeled by the system. Even if all such information is explicitly represented in the system and is capable of being queried on and textually answered, simply viewing or hearing the appropriate media object can invoke an emotional reaction not possible via a simple textual interface. This tutorial will discuss the state-of-the-art in the following topics: data modeling issues for images, video, and hypermedia, content-based indexing for images and video, multimedia content indicators for browsing, content-based browsing, and various prototype image databases, video databases, and hypermedia systems.

Hyper text markup language (HTML): With the recent explosion of the internet and World Wide Web, text has become more important than ever. Indeed, the native language of the web is HTML, originally designed to display simple text documents on computer screens. In a HTML, document you can specify typefaces, sizes, colors, and other properties by “making up” the text in the document with tags.HTML does not provide you with much flexibility make pretty text 5

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elements , but you may be able to lay out pleasing documents using block quote indents, tables, frames, and horizontal rules. Certainly, text is more efficient than imaginary and pictures for delivering a precise message to users. On the other hand, pictures, icons, moving images, sounds are most easily recalled and remembered by viewers. With multimedia, you have the power to blend both text and icons (sound, video, colors, and images) to enhance the overall impact and value of your messages.

Text and Fonts Text looks like the easiest medium to create and the least expensive to transmit, but there’s more to text creation than meets the eye! First, effective use of text requires good writing, striving for conciseness and accuracy. • Advertising wordsmiths sell product lines with a logo or tag lines with just a few words • Similarly, multimedia developers are also presenting text in a media-rich context, weaving words with sounds, images, and animations • Design labels for multimedia title screens, menus and buttons using words with the precise and powerful meanings • Which feedback is more powerful: “That answer was correct.” or “Terrific!” o When is “Terrific” more appropriate or effective? o Why is “quit” more powerful than “close”? Why does UM uses “out” instead? • Why is the title of a piece especially important? o It should clearly communicate the content. o It should get the user interested in exploring the content. • Let’s discuss some of your proposed project titles. Some guidelines for writing effective script: • Write for your audience, bearing in mind your audience’s background and interests o Can you assume that your audience knows what the traveling saleman problem is?  Yes, if your audience is CS faculty; no, if it’s CS undergraduates. o When should you use a casual, idiomatic style or a formal, business-like style?  Again, it depends on your audience. • Recommended reading for writers: The Elements of Style, by William Strunk, full of pithy advice and rules of thumb: o Say it in active voice: “Genetic algorithms were invented by John Holland in 1970’s.” vs. “John Holland invented genetic algorithms in the 1970's.” o Avoid wordiness: “computer algorithm” vs. just “algorithm” o Avoid high-falutin’ phrases: “appropriate incorporated” vs. “using” • Write and rewrite, bearing in mind that users won’t read much on a screen. 6

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Fonts Once you’ve chosen your words, you need to decide how to present them, using a typeface and font See http://www.eecs.lehigh.edu/~glennb/mm/pics/typefont.jpg (from Vaughan) a typeface is a family of graphic characters that usually includes many type sizes and styles e.g., Times, Courier and Helvetica are typefaces, each of which include many sizes & styles a font is a collection of characters of a single size and style, belong to a typeface family typical font styles are boldface, italic, bold italic, and underlined font sizes are expressed in terms of points, where one point is .0138 or 1/72 inch, where size is the distance from the top of capital letters to the bottom of descenders in lower-case letters such as g and j. Times is a typeface; Times 12-point italic is a font In computerese, however, people say “font” when “typeface” would be more accurate. Leading (pronounced “ledding”) is the space between lines of text Lopuck recommends increasing the leading to improve readability of text on a screen Character metrics are the measurements of individual characters Vector-based fonts permit changes to character metrics for interesting effects; bit-based fonts do not Kerning is the spacing between character pairs Some fonts have variable kerning (e.g., Times), so have fixed kerning (e.g., Courier) When is fixed kerning more desirable? (Computer code) What about variable kerning? A serif font has little decorations at the end of each letter stroke Times and Century Schoolbook are examples of serif fonts; Arial is a sans serif font On printed pages, serif fonts are traditionally used for body text because they help guide the reader’s eye along the line of text Headlines use sans serif text Computer screens, with 72-dpi (dots per inch), don’t provide as much resolution as print, so it can be argued sans serif fonts are more legible in small sizes hence, UM standardized on 12-point Arial font (in Windows) PostScript vs. TrueType For the Macintosh, Apple chose a resolution of 72 pixels per inch, corresponding to standard font resolution for print of 72 points per inch This allows desktop publishers to have WYSIWYG, approximately Mac also standardized pixels as square-shaped, so that measurements are even on all sides On the PC side, VGA imitated these standards (earlier, EGA had an aspect ratio of 1.33:1, taller than wide) VGA and Mac standardized no 640 x 480 square-pixel screens, now the defacto baseline for multimedia production So far, the good news... 7

Text media Apple also spearheaded desktop publishing by adopting Adobe’s PostScript page description language for printing to Apple’s LaserWriter Until then, characters were stored in a bitmap table representing every character at every size PostScript is vector-based, describing each character in terms of mathematical constructs (Bezier curves), so that each character can be scaled This facilitates drawing characters at various sizes and in various resolutions A problem with PostScript is that it represents fonts for printer and screens separately Adobe Type Manager accesses a font’s outline in the printer font, and scales it to display to the right size on a screen Apple apparently didn’t like Adobe’s approach, so they later (circa 1989) introduced TrueType you only need one file per font, for either printer or screen, nor do you need ATM utility TrueType also uses a quadratic curves outline font method, which Apple and others claim produces a smoother characters Now Truetype is generally available on all Windows and Macintosh systems Both PostScript and TrueType fonts allow text to be drawn on any size without jaggies or jagged edges on the outlines of a character, such as in a bold italic style Anti-alaising exploits color by blending (or dithering) the colors along the edges of letter Authorware 5 now boast support for anti-aliasing See http://www.eecs.lehigh.edu/~glennb/mm/pics/MacPCfnt.jpg for comparison Since PostScript and TrueType are now fairly universal, it’s fairly safe to use them without worrying about portability, though not all fonts are identical on each platform Authorware and Director point out possible problems with mapping fonts and suggests possible solutions For example, Arial on Windows apparently maps approximate to Helvitica on Mac However, these are not exactly equivalent, so porting text is not trivial! Also, special characters, such as curling quotation marks, rarely map properly. One way to solve font mapping problems is to convert text into bitmaps If you want to use other fonts, you either create them yourself, or obtain from a font manufacturer (sometimes known as a type foundry), such as Adobe, and Bitstream, Monotype, etc. These and other interesting fonts are available on the web, e.g., www.bitstream.com Some more heuristics about choosing text fonts: For small type, avoid decorative fonts; strive for legibility Use as few different typefaces in a piece, but vary the style and size where it looks good Also experiment with different colors and different backgrounds In blocks of text, use ample leading, i.e., space between lines of text Avoid scrolling text; test show that users will gloss over all your information! Keep length of each line short. Lopuck recommend keeping line length under 3". User’s eyes can get lost finding the next line if the lines are too long. I try to end each line with a punctuation mark if possible. Use anti-aliased text for a gentle and blended look for titles and headlines For attention-grabbing headlines, try graphically altering the text, using a font editing tool such as ResEdit or Fontographer, or use drop shadows or three-dimensional effects 8

Text media Surround headlines with plenty of white space

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