In multimedia applications, sound that has been digitized is called audio. Audio can be obtained by capturing sound into a personal computer using a microphone, CD-ROM, or other input device. It can also be played from a synthesizer, keyboard, or other musical instrument that is connected to the computer using a MIDI (musical instrument digital interface) port.
Sound is made when objects vibrate producing pressure waves that can be picked up by our ears. Sound, or technically speaking, audio signal, is a time dependent variation of air pressure. Sound is an ANALOGUE signal.)
To convert an analogue signal to a digital signal, two operations are required:
The analogue signal must be evaluated at certain instances.
The detected analogue values must be converted to binary digital values.
For each of the two operations a certain device will be required. Each evaluation and conversion of an analogue value, thus each DIGITAL SAMPLE of the analogue signal, will produce a certain amount of data. If a certain time, e.g. 1 second, of a analogue signal is to be converted to a digital signal, the amount of binary data produced depends on:the number of samples taken during the period and also the number of bits used to represent one sample.
Satisfactory conversion of audio signals to digital form requires representing each sample.By at least 12 bit and to take at least 30 000 samples per second. This produces a DATA STREAM of 360 000 bit/s.
MP3 (MPEG-1 Audio Layer-3) is a standard technology and format for compression a sound sequence into a very small file (about one-twelfth the size of the original file) while preserving the original level of sound quality when it is played. MP3 files (identified with the file name suffix of ".mp3") are available for downloading from a number of Web site. Many MP3 files are usually download-and-play files rather than streaming sound files that you link-and-listen-to with RealPlayer and similar products (However, streaming MP3 is possible.) Winamp (PC), MacAmp (Mac), and mpeg123 (UNIX) are popular MP3 players, but there are many others.
A Wave file is an audio file format, created by Microsoft, that has become a standard PC audio file format for everything from system and game sounds to CD-quality audio. A Wave file is recognized by a file name extension of WAV (.wav). Used primarily in PCs, the Wave file format has been accepted as a viable interchange medium for other computer platforms, such as Macintosh. This allows content developers to freely move audio files between platforms for processing, for example.In addition to the uncompressed raw audio data, the Wave file format stores information about the file's number of tracks (mono or stereo), sample rate, and bit depth.
A sequencer is a program in a computer or stand-alone keyboard unit that puts together a sound sequence from a series of Musical Instrument Digital Interface (MIDI) events. The MIDI sequencer allows the user to record and edit a musical performance without using an audio-based input source.
3-Animation & Graphics
Animation: is a series of images but together to give the effect of movement. Animation is used to add visual interest or illustrate attention to important information or links in a multimedia application. Animation is commonly used in advertising marketing, movies because the movement of animation take a user attention
Graphics are any type of image produce using the computer. 2D and 3D images are important to multimedia development. In fact, multimedia applications are mostly graphics. Adding just the right graphic and just the right number of graphics may help the user learn and retain more information in less time and with less effort. Photographs can also be used to enhance multimedia applications. Photographs can be digitised through a colour scanner or taken directly with a digital camera Collections of digital photographs called stock photography.
Image file: The image file that used in animation and graphics are as follows:JPEG,BMP and GIF.
Bitmap- Bitmap graphic displays the image by using pixels. The numbers of pixels per unit length measures image resolution using inches so that this can defines the finely details of the image. “There are two different types of image format for example GIF and JPEG, this store the number of pixel per inches so that the image can be displayed or printed at the right size”. Bitmap image can originate from many different types of source, such as digital camera, video, scanned pictures or even from clip art.
Vector-Vector graphics uses co ordination, It uses straight lines, ovals and arcs. When a line is drawn, it sets the instruction, which describes its size, position and shape. When a vector “graphic is displayed, the display software converts two co-ordinates of the line into an array of pixels’’ by working out whether to display each pixels in the image as white or black. Vector is often used for graphics that needs to retain distinctive lines when their sizes change, such as logos. When using vector graphics it can be very easily scaleable without loosing any resolution and can manipulate elements of an image.
Morphing- is transition. It is also one of the most complex ones. A morph looks as if two images melt into each other with a very fluid motion. In technical terms what happens is, two images are distorted and a fade occurs between them. This is pretty complicated to understand,
Warping is the same as morphing, except only one image is distorted and no fades occurs.
Cel and path animation Cel animation is based on changes that occur from one frame to another, which give the effect of movement. the image is drawn a clear sheet. And then it is placed on a still background. The background remains the same as the object changes from frame to frame.
Path animation, move an object along a preset path on screen. The path might be could a straight or have curves .the object can be resizing or rotated.
Authoring is a multimedia program, which helps the developers to produce content with paint, text, animation and many more other elements. This program mainly used to create slide shows, which can be displayed to be self-running. It is also used extensively as a web-based lecturer in online courses. Authoring is a very easy to learn and use software, which. “It provides a template with different background colour and graphics”. Authoring program could be used on Macintosh and Windows computer and is not cost effect able .
Metaphors
Lingo –programme language used by director.
Copyright.provides legal protection and grants certain rights to its owner. The author of the image is usually the owner of the copyright,unless the author has transferred copyright ownership to some one else.
Video conferencing- Using videoconferencing technology, two or more people at different locations can see and hear each other at the same time, sometimes even sharing computer applications for collaboration. This rich communications technology offers new possibilities for schools, colleges, and libraries, who are now using videoconferencing systems for a variety of purposes, including formal instruction (courses, lessons, and tutoring), connection with guest speakers and experts, multi-school project collaboration, professional activities, and community events
Video can be the most exciting feature of multimedia application. A video clip or an animation sequence can express an idea in a much better way than text or images. Video clips used in multimedia systems are more flexible in the sense that they are EASIER TO EDIT and also EASIER TO ACCESS.
Video format-A video format describes how one device sends a video pictures to another device, An example would be the way that a sends pictures to t.v or a computer to a monitor. More formally, the video format describes the sequence and structure of frames that create the moving video image.
Copyright laws on the video- A copyright is a form of intellectual property that grants its holder the legal right to restrict the copying and use of an original, creative expression, such as a literary work, movie, musical work or sound recording, painting, computer program, or industrial design for a defined period of time.
Compression and decompression
Virtual reality. Virtual Reality is generally speaking an attempt to provide more natural, human interfaces to software. It can be as simple as a pseudo 3D interface or as elaborate as an isolated room in which the computer can control the user's senses of vision, hearing, and even smell and touch.
