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Multimedia Technology

All about multimedia! hence the title!
by

Sarah Fraser

on 24 April 2013

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Transcript of Multimedia Technology

By Sarah Fraser ( Frazzles) Multimedia Multimedia Technology! Synthesized Sound data What does Multimedia mean?

An interactive piece of software using several types of Media:

Text
Graphics(photographs or illustrations)
Audio(synthesised or digitalised)
Video
Animation
I have experienced Multimedia software by using, Fruit Ninja the game for your ipod, BBC iplayer, Skype, Videos/Photographs on my phone ect. Software Development process There are various methods used to create multimedia application. We are going to look at: Text editors, WYSIWYG editors, Authoring software and Presentation software. Creating MM Applications Musical instrument digital inteface: MIDI 1.Analysis - The main purpose of this stage is to be absolutely clear about what the multimedia project is supposed to do. The client needs to be specific with details like: Who is the game for?, What device is the game for? , Type of application? ect.
2. Design - Producing a detailed plan which defines what the different parts of the project are an how they are linked together. There are two types of storyboards : Outline Storyboard and Detailed Storyboard, these are all apart of design.
3. Implementation - This is the point at which the multimedia authoring, or web-page authoring, pakage is used to turn the design into a working project. Eg. How is it going to be delivered? Mobile phone ap, CD/DVD, Website ect.
4.Testing - A series of practical tests are carried out to check that the multimedia project functions properly.
5.Documentation - A User guide and a Technical guide need to be produced with the application.
6.Evalutation- Checks that the finished application meets the user's requirements. Includes an assesment of the HCI design.
7.Maintenance- Fixing bugs and adapting the design to suit client needs and demands of new technology. This process can be applied when developing multimedia project. This is an example of a detailed storyboard: Text Editor: An example is Notepad. An Application is created using plain text e.g. Creating simple web pages using HTML. WYSIWYG Editors: previewing applications under development to check that What You See Is What You Get. Authoring Software: There are two types of Authoring Software.
Icon Based- Setting up of the properties without the need to learn programming. Script Based- program code or scripting Presentation Software: Enables the creation of sequence of slides. Allows hyper linking to different slides.
For Example: Prezi, Power Point ect. Viewing your MM application Web Browser: Multimedia applications can be viewed/displayed using a web browser

File 'Player': Multimedia applications can also be viewed via a file player or viewer Internet explorer Safari Windows Media player Exe File: This is an executable file. This is a file format which allows programs to preform tasks which are made in encoded instructions. Microsoft windows This is used in mobiles. 'DOS' - Disk Operating System Image Quality and File Size
Resolution: spacing of pixels in a picture measured dots per inch (dpi). Increasing resolution increases the number of pixels. This can improve the quality of a graphic but increases the file size.
Colour Depth: If we use coloured pixels, then the amount of memory used increases. This is because more than 1-bit of memory has to be used to store a pixel.

Lossy Compression: reduces the file size and providing the rate of compression is not too high does not affect the quality of the graphic. Main features of Image editing software
Decrease resolution

Insert graphic

Alter colour depth

Re-size or scale an image

Crop

Alter brightness and contrast Hardware for Displaying Graphics
LCD Screen - Flat, light, needs less power, more expensive than CRT
CRT Screen - Bulky, heavy, run on mains power, cost less than equivalent TFT screens
Graphics Card - A graphics card is required to store and process graphic data, relieving the main processor of the task Graphics can be stored:
in Bitmap(Each pixel in the image is represented by a binary number. A file which is uncompressed holds a binary number for each pixel in an image. The main limitation of a bitmap format is its large file size. In order to reduce the file size and relieve the demands on storage and transmission times requires compression.)
and GIF(Graphics Interchange Format,compresses graphic data without losing any information about the image. It compresses by encoding repeated patterns of data. The graphics interchange format supports 256 colours and needs 1 byte per pixel to encode a graphic. A GIF format is used for storing cartoons and line drawings.) CCD - Charged Coupled Device- uses sensors to capture light and then convert into analogue electrical signals. Currently only see light levels not colour.

ADC- Analogue/Digital Converter
Converts the analogue signals into digital signals so that the computer can process them. Digitised Sound Data How can we capture sound? CD/DVD - Digital device used for capturing music files. Copyright laws may apply.
Microphone- An analogue device which can be used for voice-overs
Sound Cards- Used to sample, store and process audio data Sampling depth What is sampling depth? Sampling depth is the number of bits which are taken in each sample. The higher the sound depth the greater range of values which results in the increased quality and file size. Increased sound depth = greater range of values
= better sound quality and greater file size Sampling Frequency What is sampling frequency? The sampling frequency is the number of samples taken per second.
The higher the sampling frequency, the better the sound quality and file size. How is sound stored? RAW: Uncompressed samples of sound waves which has not been processed further.

RIFF: Resource Interchange File Format. This is a container file which can contain various types of data e.g. Video, bitmaps, sound, etc.

WAV: Wave files are RIFF files containing digitised sound data. WAV files are often used in places such as digital telephone systems and mini disc players.

MP3 MPEG Audio Layer-3. MP3 uses lossy compression, this reduces the file sizes by cutting out some of the data without noticeable loss of sound quality. Sound Time(s) and File Size How does the clip time affect file size? Sound Time(s) This is the duration of the clip in seconds. The longer the clip the larger the file size. Affects the file size but not the quality.

File Size: The size of the file can be measured in bytes, Kb, Mb and Gb. Sound Editing Software Simple Sound Editing Software

Reducing sampling frequency, e.g. from 44.1 Khz to 20.05 Khz, reduces the file size and audio quality.
Reducing sample depth e.g. From 16 bits to 8 bits per sample, reduces file size and audio quality. Features : Crop - shortening the track or even removing parts of it. You can create an audio loop or grab a sample that can be used in another track.

Volume - adjust the volume if sections or tracks within the sample. By changing the volume of various instruments, you can mix your own track.

Effects -you can apply a range of effects such as adding echo /reverb or even reversing sections of the track so that it runs backwards Sound Cards What is a Sound Card?
Sound cards are needed to change the digital audio data into analogue signals to control output from speakers.
They contain processors and memory chips. They are installed in your computer and they take over some of the hard work of the processing of the sound card.

Tasks that a sound card can do are:
1. Record audio straight onto the hard disk
2. It can playback audio tracks from CDs and DVDs
3. Sound synthesis
4. Interfacing with MIDI instruments Video Data : This is a sequence of pictures called frames, that are shown in a sequence to immitate a moving image by tricking the brain into filling in the gaps. Each of the pictures in a video clip is a bitmap image. Hardware for capturing images: The main pieces are Webcam and Digital video camera. Graphics card or Video card - This card is involved with inputing and outputing data to and from you computer. It may also do some proccessing if compression is involved. Storing Video Data : Uncompressed - Uncompressed video data results in large file sizes. One second of uncompressed wide screen video can take up 53MB of backing storage. A Example of uncompressed file format is AVI(Audio Visual Interleave)
Compressed Format- The most common usage of compressed format is MPEG(Motion Picture Expert Group). This Format uses LOSSY compression to reduce file size without noticable loss of video quality. Video Quality and File Size: Colour Depth- Increasing colour depth improves quality and increases the file size( bytes)
Resolution- Increasing resolution improves quality and increases file size (DPI)
Frame Rate- Measured in Frames per second(FPS). 30 FPS is the standard rate for a video clip. Increasing frame rate increases file size. More frame rates reduce file size but make video clips jerky.
Video Time- The obvious way to affect the file size is to increase or reduce the time of a video. The quality of a display of a clip is not affected.
LOSSY Compression- Uses MPS compression reduces file sizes without affecting the quality. The technique involves storing only some of the frames in the clip. These key frames are stored normally, the format then stores the differences between individual frames. Storing changes takes up less space than storing whole frames. Video Editing software, features and applications used with single video clips. : The main features of simple video editing software are :
-Cropping- Cutting unwanted data from the beginning and end of a clip
-Importing or exporting clips to use else where
-Rearranging the sequence in which the clips run on the timeline
-Adding transitions e.g. fade, dissolve and jump
-Adding a sound track
-Adding visual or sound affects Vector Graphics Basic features of vector graphics : A vector or object/ oriented graphic is made up of shapes, layered on top of one another to make a picture. They are scallable which mean because they are a mathmatical description of the shape to be drawn it can be scalled without loss of quality known as resolution independent. In a vector graphic individual objects can be edited and duplicated, moved or manipulated with ease. Graphics can be assembled by placing objects in layers and then treated as a single unit. Common attributes : Drawing- Each object in the picture is described mathamatically as a list of attributes. These fully describe the type of object, position on screen, its size and the colour/pattern of its outline(called line) and middle(called fill). Other attributes might be the degree of any rotation and which layer it is on.
3D- It is possible to draw 3D objects using vector graphics. Attributes of the 3D objects are the same as flat 2D objects but include additional attributes such as Angle of rotation, surface texture and shadow. File types : Scalable vector graphics thats SVG format.
Scallable= resolution independent,
Vector= represents objects by defining a series of attributes
VRML(Virtual reality market language)- standard language ised to model and animate geometric. Used to define 3D enviroments for the world wide web.

WRL( world description language) Common attributes of notes stored as MIDI data: Instrument- defines what instrument is playing.
Pitch- Defines the height of the note
Volume- determines the amplitude
Duration- determines the length of the note
Tempo- The speed at which a piece of music is played

MIDI is both file extension/type and an inteface. MIDI keyboards, or other instuments are used to create sound data in MIDI format. You dont even need the instruments as there are software packages that allow you to create and edit MIDI files from your computer. Implications of the use of multimedia technology Conversion, contemporary technologies Smartphone; This is merging technologies of a mobile phone and a laptop
Pocket PC: Merging technologies of a laptop, moblie phone and desktop operating system and application software.
Digital Television: An interactive multimedia device which, because of the digital nature of its signals is easily intergrated into your digital computer and home network.
Virtual Reality: The ultimate multimedia experience, when the user is immersed in the world of the computer and can journey through, and interact with, a computer generated 3 dimensional multimedia world.
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