MULTIMEDIA

Multimedia Authoring Tools

Use to merge multimedia elements (text, audio, graphic, animation, video) into a project.

Designed to manage individual multimedia elements and provide user interaction (if required).

Categories of Authoring Tools

Can be categorized into

1. Presentation software

2. Tools for creating production

3. Interactive training and education

1. Presentation software

Enable users to create and deliver business presentations in the form of the slide show.

Each major heading is the beginning of a new slide.

1. Presentation software

Templates are used to determine how the heads and subheads are formatted and displayed over backgrounds, including: (etc PowerPoint)

position

size

font

style

color

Example: PowerPoint Interface

2. Tools for creating production

Typically oriented toward producing content that is more ambitious than the slide-show level

(more interactive & dynamic)

Usually integrate all types of' multimedia data into a multitrack timeline that determines the evolution of events 

3. Interactive training and education tools

To create education or training content.

Designed primarily to present information in an Interactive book.

Multimedia-oriented programming languages such as Visual Basic represent another authoring alternative.

Offers the higher flexibility, performance speed and power

Example: Macromedia Flash, Authorware & Director

Types of Authoring Tools

1. Card based

2. Icon based

3. Time based

4. Object based

1. Card Based

Cards are developed that have different elements associated with them.

Cards are put in stack.

Cards or pages combine to make up a book.

example of authoring tools

HyperCard (Mac)

ToolBook (Mac / Windows)

2. Icon Based

Icons are gathered along the line.

Provide visual development.

Flow chart is created to show the organisation of icons or elements:

including activity list, results and done with dragging the icon/elements along the lines

each Icon represents a particular event – button, graphics, text, video

examples of authoring tools

Authorware(Mac/Windows)

IconAuthor (Windows)

2. Icon Based

3. Time Based

The most popular used.

Using “timeline” for organizing activities

Also using “framing” – timely adjusted depending on the frame size

Example:- Macromedia Director / Flash (Mac/Windows)

3. Time Based

4. Object Based

Support environment based on object.

Every object is modified using properties & modifiers

The environment is based on ‘Hierarchy’ (section and sub-section).

Examples of the tools :

mTropolis (Mac/Windows)

AppleMedia Tool (Mac/Windows)

MediaForge (Windows)

SOUND

ANIMATION

DATA COMPRESSION

Why Data Compression?

Make optimal use of limited storage space

Save time and help to optimize resources

If compression and decompression are done in I/O processor, less time is required to move data to or from storage subsystem, freeing I/O bus for other work

In sending data over communication line: less time to transmit and less storage to host

Data Compression- Entropy

Entropy is the measure of information content in a message.

Messages with higher entropy carry more information than messages with lower entropy.

How to determine the entropy

Find the probability p(x) of symbol x in the message

The entropy H(x) of the symbol x is:

H(x) = - p(x) • log2p(x)

The average entropy over the entire message is the sum of the entropy of all n symbols in the message

Data Compression Methods

Data compression is about storing and sending a smaller number of bits.

There’re two major categories for methods to compress data: lossless and lossy methods

Lossless Compression Methods

In lossless methods, original data and the data after compression and decompression are exactly the same.

Redundant data is removed in compression and added during decompression.

Lossless methods are used when we can’t afford to lose any data: legal and medical documents, computer programs.

Run-length encoding

Simplest method of compression.

Replace consecutive repeating occurrences of a symbol by 1 occurrence of the symbol itself, then followed by the number of occurrences.

The method can be more efficient if the data uses only 2 symbols (0s and 1s) in bit patterns and 1 symbol is more frequent than another.

Algorithm:

1. Make a leaf node for each code symbol

2. Add the generation probability of each symbol to the leaf node

3. Take the two leaf nodes with the smallest probability and connect them into a new node

4. Add 1 or 0 to each of the two branches

5. The probability of the new node is the sum of the probabilities of the two connecting nodes

6. If there is only one node left, the code construction is completed. If not, go back to (2)

Huffman Coding

Example

Huffman Coding

Encoding

Decoding

Algorithm:

1. Extract the smallest substring that cannot be found in the remaining uncompressed string.

2. Store that substring in the dictionary as a new entry and assign it an index value

3. Substring is replaced with the index found in the dictionary

4. Insert the index and the last character of the substring into the compressed string

Lempel Ziv Compression

Compression

example:

Lempel Ziv Decompression

It’s just the inverse of compression process

The JPEG then applies differential encoding(DC) or ZigZag ordering on the quantized table. Finally Huffman Coding is applied for data compression.

Evolution of MPEG MPEG-1 Initial audio/video compression standard Used by VCD’s MP3 = MPEG-1 audio layer 3 Target of 1.5 Mb/s bitrate at 352x240 resolution Only supports progressive picturesEvolution of MPEG MPEG-2 Current de facto standard, widely used in DVD and Digital TV Ubiquity in hardware implies that it will be here for a long time

Transition to HDTV has taken over 10 years and is not finished yet Different profiles and levels allow for quality control

Evolution of MPEG MPEG-3 Originally developed for HDTV, but abandoned when MPEG-2 was determined to be sufficient MPEG-4 Includes support for AV “objects”, 3D content, low bitrate encoding, and DRM In practice, provides equal quality to MPEG-2 at a lower bitrate, but often fails to deliver outright better quality MPEG-4 Part 10 is H.264, which is used in HD-DVD and Blu-Ray

MPEG Block Diagram