A hypermedia message may be a simple message in the form of text with an embedded graphics, sound track, or video clip, or it may be the result of analysis of material based books, CD ROMs, and other on-line applications.
Hypermedia Message Components A hypermedia message may be asimple message in the form of text with an embedded graphics, sound track, orvideo clip, or it may be the result of analysis of material based books, CDROMs, and other on-line applications. An authoring sequence for a message basedon such analysis may consist of the following components. 1.The user may have watched some video presentation on the materialand may want to attach a part of that clip in the message. While watching it,the user marks possible quotes and saves an annotated copy. 2.Some pages of the book are scanned as images. The images provide anillustration or a clearer analysis of the topic 3.The user writes the text of the message using a word processor. Thetext summarizes the highlights of the analysis and presents conclusions. These three components mustbe combined in a message using an authoring tool provided by the messagingsystem. The messaging system must prompt the user to enter the name of theaddressee forthe message. The message system looks upthe name in an online directory and convert it to an electronic addresses wellas routing information before sending the message. The user is now ready tocompose the message. The first step is to copy the word processed text reportprepared in step 3 above in the body area of the message or use the text editorprovided by the messaging system. The user then marks the spots where theimages are referenced and uses the link and embed facilitites of the authoringtool to link in references to the images. The user also marks one or more spotsfor video clips and again uses the link and embed facilities to add the videoclips to the message. When the message is fullycomposed, the user signs it (electronic signature) and mails to the message tothe addressee (recipient). The addressing system must ensure that the imagesand video clips referenced in the message are also transferred to a server"local' to the recipient. Text Messages In earlier days, messagingsystems used a limited subset of plain ASCII text. Later, messaging systemswere designed to allow users to communicate using short messages. Then, newmessaging standards have added on new capabilities to simple messages. Theyprovide various classes of service and delivery reports. Pratap To : Karan Copy to: Madhan Date : 01Jan'07
subject: WISHING A HAPPY NEWYEAR Hai Karan,
I wish you a very bright andprosperous new year. - Pratap Delivery notification: Normal Priority: High
Typical Electronic mail message
Other capabilities ofmessaging systems includ~ a name and address directory of all users accessibleto the messaging system.
Rich-Text Messages
Microsoft defined a standardfor exporting and importing text data that included character set, font table,section and paragraph formatting, document formatting, and colorinformation-called Rich Text Format (RTF), this standard is used for storage aswell as Import and export of text files across a variety of word-processing andmessaging systems.
When sections of thisdocument are cut and pasted into another application, the font and formattinginformation is .retained. This allows the target application to display thetext m the nearest equivalent fonts and formats.
Rich-text messages based onthe RTF formats provide the capability to create messages in one word processorand edit in another at the recipient end. Most messaging systems provIderichtext capability for the field of a message.
Voice Messages
Voice mail systems answertelephones using recorded messages and direct the caller through a sequence oftouch tone key operations until the caller is connected to the desired party oris able to leave a recorded message.
Audio' (Music)
The Musical InstrumentDigital interface (MIDI) was developed initially by the music industry to allowcomputer control of and music recordings from musical instruments such asdigital pianos and electric keyboards. MIDI interfaces are now being used for avariety of peripherals, including digital pianos, digital organs, video gameswith high-fidelity sound output, and business presentations.
Full-Motion Video Management
Use of full-motion video forinformation repositories and memos are more informative. More information canbe 'conveyed and explained in a short full-motion video clip than can beconveyed In a long text document. Because a picture is equivalent to thousandwords.
Full Motion video Authoring System
An authoring system is animportant component of a multimedia messaging system. A good authoring systemmust provide a number of tools for the creation and editing of multimediaobjects. The subset of tools that are necessary are listed below:
1. A video capture program - toallow fast and simple capture of digital video from analog sources such as avideo camera or a video tape. .
2.Compression and decompression Interfaces for compressing thecaptured video as it is being captured.
3.A video editor with the ability to decompress, combine, edit, andcompress digital video clips.
4.Video indexing and annotating software for marking sections of avideoclip and recording annotations.
Identifying and indexingvideo clips for storage.
Full-Motion Video Playback Systems
Theplayback system allows the recipient to detach the embedded vIdeo referenceobject, Interpret its contents and retrieve the actual video clip from aspecialized video server and launch the Playback application. A number of factorsare involved in playing back the video correctly.
They are:
1.How the compression formatused for the storage of the video clip relates to the available hardware andsoftware facilities for decompression.
2.Resolution of the screenand the system facilites available for managing display windows. The displayresolution may be higher or lower than the resolution of the source of thevideo clip. 3.The CPU processing power and the expected level of degradation aswell as managing the degraded output on the fly.
4.Ability to determinehardware and software facilities of the recipient's system, and adjustingplayback, parameters to provide the best resolution and perfonnance onplayback.
The three main technologiesfor playing full motion video are microsoft's video for windows: Apple'sQuicktime, and Intel's Indeo.
Video for Windows (VFW): It is the most common environment formultimedia messaging.
VFW provides capture, edit,and playback tools for full-motion video. The tools provided by VFW are: TheVidCap tool, designed for fast digital video capture.
The VidEdit tool designed fordecompression, edition, and compressing full-motion digital video. The VFWplayback tool.
The VFW architecture usesOLE. With the development of DDE and OLE, Microsoft introduced in windows thecapability to link or multimedia objects in a standardized manner. Hencevariety :;windows based applications can interact with them. We can addfull-motion video to any windows-based application with the help ofVFW. The VFWplayback tool is designed to use a number of codecs (software encoder/decoders)for decompressing and playing video files. The default is for A VI files.
Apple's QuickTime
An Apple QuickTime product isalso an integrated system for playing back video files. The QuickTime productsupports four compression methodologies.
Intel's Indeo
Indeo is a digital videorecording format. It is a software technology that reduces the size of uncompressed video files through successive compression methodologies, including YUVsub sampling, vector quantization, Huffman's run-length encoding, and variablecontent encoding. Indeo technology is designed to be scalable for playing backvideo; It determines the hardware available and optimizes playback for thehardware by controlling the frame rate. The compressed file must bedecompressed for playback. The Indeo technology decompresses the video filedynamically in real time for playback. Number of operating systems provideIndeo technology as standard feature and with other software products (eg.VFW).
Hypermedia Linking and Embedding
Linking and embedding are twomethods for associating multimedia objects with documents.
Linking Objects
When an object is linked, thesource data object, called the link source, continues to stay whenever it wasat the time the link was created. This may be at the object server where it wascreated, or where it has been copied.
Only reference is required inthe hypermedia document. The' reference is also known as link. This linkreference includes information about the multimedia object storage, itspresentation parameters, and the server application that is needed todIsplay/play or edit it. When this document is copied, the link reference istransferred. But the actual multimedia document remains in its originallocation. A linked object is not a part of the hypermedia document and it doesnot takeup storage space within the hypermedia document. If the creator, orauthorised user edits the original stored multimedia object, subsequent callsto the linked object bring the copy.
Embedded Objects
If a copy of the object isphysically stored in the hypermedia document, then'the multimedia object :3said to be embedded. Any changes to the original copy of t4at object are notreflected in the embedded copy. When the hypermedia document is copied, themultimedia object is transferred with it to the new locations.
Graphics and images can beinserted in a rich-text document on embedded using such techniques as OLE Voiceand audio components can be included in a text message; or they cim be part ofa full voice-recorded message that has embedded text and other components.
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