Q.1 What Is MPEG? What Are Its Different Standards ?

Q.1 What is MPEG? What are its different Standards ?

Ans - The Moving Picture Experts Group (MPEG) is a working group of authorities that was formed by ISO to set standards for audio and video compression and transmission. It was established in 1988. The term also refers to the family of digital video compression standards and file formats developed by the group. MPEG generally produces better-quality video than competing formats, such as Video for Windows, Indeo and QuickTime. MPEG files previously on PCs needed hardware decoders (codecs) for MPEG processing. Today, however, PCs can use software-only codecs including products from Real Networks, QuickTime or Windows Media Player.MPEG algorithms compress data to form small bits that can be easily transmitted and then decompressed. MPEG achieves its high compression rate by storing only the changes from one frame to another, instead of each entire frame. The video information is then encoded using a technique called Discrete Cosine Transform (DCT). MPEG uses a type of lossy compression, since some data is removed. But the diminishment of data is generally imperceptible to the human eye.

The major MPEG standards include the following;

• MPEG-1: The most common implementations of the MPEG-1 standard provide a video resolution of 352-by-240 at 30 frames per second (fps). This produces video quality slightly below the quality of conventional VCR videos.
• MPEG-2: Offers resolutions of 720x480 and 1280x720 at 60 fps, with full CD-quality audio. This is sufficient for all the major TV standards, including NTSC, and even HDTV. MPEG-2 is used by DVD-ROMs. MPEG-2 can compress a 2 hour video into a few gigabytes. While decompressing an MPEG-2 data stream requires only modest computing power, encoding video in MPEG-2 format requires significantly more processing power.
• MPEG-3: Was designed for HDTV but was abandoned in place of using MPEG-2 for HDTV.
• MPEG-4: A graphics and video compression algorithm standard that is based on MPEG-1 and MPEG-2 and Apple QuickTime technology. Wavelet-based MPEG-4 files are smaller than JPEG or QuickTime files, so they are designed to transmit video and images over a narrower bandwidth and can mix video with text, graphics and 2-D and 3-D animation layers. MPEG-4 was standardized in October 1998 in the ISO/IEC document 14496. See MPEG-4.
• MPEG-7: Formally called the Multimedia Content Description Interface, MPEG-7 provides a tool set for completely describing multimedia content. MPEG-7 is designed to be generic and not targeted to a specific application.
• MPEG-21: Includes a Rights Expression Language(REL) and a Rights Data Dictionary. Unlike other MPEG standards that describe compression coding methods, MPEG-21 describes a standard that defines the description of content and also processes for accessing, searching, storing and protecting the copyrights of content.

Q.2 – What is LZW Algorithm? Illustrate it using Example?

Ans- Lempel–Ziv–Welch (LZW) is a universal lossless data compression algorithm created by Abraham Lempel, Jacob Ziv, and Terry Welch. It was published by Welch in 1984 as an improved implementation of the LZ78 algorithm published by Lempel and Ziv in 1978. The algorithm is simple to implement, and has the potential for very high throughput in hardware implementations. It was the algorithm of the widely used UNIX file compression utility compress, and is used in the GIF image format.

Encoding

A high level view of the encoding algorithm is shown here:

1. Initialize the dictionary to contain all strings of length one.
2. Find the longest string W in the dictionary that matches the current input.
3. Emit the dictionary index for W to output and remove W from the input.
4. Add W followed by the next symbol in the input to the dictionary.
5. Go to Step 2.

Decoding

The decoding algorithm works by reading a value from the encoded input and outputting the corresponding string from the initialized dictionary. In order to rebuild the dictionary in the same way as it was built during encoding, it also obtains the next value from the input and adds to the dictionary the concatenation of the current string and the first character of the string obtained by decoding the next input value, or the first character of the string just output if the next value can not be decoded (If the next value is unknown to the decoder, then it must be the value that will be added to the dictionary this iteration, and so its first character must be the same as the first character of the current string being sent to decoded output). The decoder then proceeds to the next input value (which was already read in as the "next value" in the previous pass) and repeats the process until there is no more input, at which point the final input value is decoded without any more additions to the dictionary.

The LZW Compression Algorithm can summarised as follows:

w = NIL;

while ( read a character k )

{

if wk exists in the dictionary

w = wk;

else

add wk to the dictionary;

output the code for w;

w = k;

}

• Original LZW used dictionary with 4K entries, first 256 (0-255) are ASCII codes.

Example:

Input string is "^WED^WE^WEE^WEB^WET".

W / K / OUTPUT / INDEX / SYMBOL
NIL / ^ / 256 / ^W
^ / W / ^ / 257 / WE
W / E / W / 258 / ED
E / D / E / 259 / D^
D / ^ / D
^ / W / 260 / ^WE
^W / E / 256 / 261 / E^
E / ^ / E
^ / W
^W / E / 262 / ^WEE
^WE / E / 260
E / ^ / 263 / E^W
E^ / W / 261
W / E / 264 / WEB
WE / B / 257 / 265 / B^
B / ^ / B
^ / W
^W / E
^WE / T / 260 / 266 / ^WET
T / EOF / T

• A 19-symbol input has been reduced to 7-symbol plus 5-code output. Each code/symbol will need more than 8 bits, say 9 bits.
• Usually, compression doesn't start until a large number of bytes (e.g., > 100) are read in.

The LZW Decompression Algorithm is as follows:

read a character k;

output k;

w = k;

while ( read a character k )

/* k could be a character or a code. */

{

entry = dictionary entry for k;

output entry;

add w + entry[0] to dictionary;

w = entry;

}

Example (continued):

Input string is "^WED<256>E<260<261<257>B<260>T".

W / K / OUTPUT / INDEX / SYMBOL
^ / ^
^ / W / W / 256 / ^W
W / E / E / 257 / WE
E / D / D / 258 / ED
D / <256> / ^W / 259 / D^
<256> / E / E / 260 / ^WE
E / <260> / ^WE / 261 / E^
<260> / <261> / E^ / 262 / ^WEE
<261> / <257> / WE / 263 / E^W
<257> / B / B / 264 / WEB
B / <260> / ^WE / 265 / B^
<260> / T / T / 266 / ^WET

Q.3- What is HTML and VRML?

Ans- VRML (Virtual Reality Modeling Language, pronounced vermal or by its initials, originally—before 1995—known as the Virtual Reality Markup Language) is a standard file format for representing 3-dimensional (3D) interactive vector graphics, designed particularly with the World Wide Web in mind. It has been superseded by X3D . VRML is a text file format where, e.g., vertices and edges for a 3D polygon can be specified along with the surface color, UV mapped textures, shininess, transparency, and so on URLs can be associated with graphical components so that a web browser might fetch a webpage or a new VRML file from the Internet when the user clicks on the specific graphical component. Animations, sounds, lighting, and other aspects of the virtual world can interact with the user or may be triggered by external events such as timers. A special Script Node allows the addition of program code (e.g., written in Java or ECMAScript) to a VRML file.

HTML or HyperText Markup Language is the standard markup language used to create web pages.HTML is written in the form of HTML elements consisting of tags enclosed in angle brackets (like <html>). HTML tags most commonly come in pairs like <h1> and </h1>, although some tags represent empty elements and so are unpaired, for example <img>. The first tag in a pair is the start tag, and the second tag is the end tag (they are also called opening tags and closing tags).The purpose of a web browser is to read HTML documents and compose them into visible or audible web pages. The browser does not display the HTML tags, but uses the tags to interpret the content of the page. HTML describes the structure of a website semantically along with cues for presentation, making it a markup language rather than a programming language.

HTML elements form the building blocks of all websites. HTML allows images and objects to be embedded and can be used to create interactive forms. It provides a means to create structured documents by denoting structural semantics for text such as headings, paragraphs, lists, links, quotes and other items. It can embed scripts written in languages such as JavaScript which affect the behavior of HTML web pages.Web browsers can also refer to Cascading Style Sheets (CSS) to define the look and layout of text and other material. The W3C, maintainer of both the HTML and the CSS standards, encourages the use of CSS over explicit presentational HTML.

Q.4 What is the Text Editing and Word Processing ?

Ans- Word processing typically implies the presence of text manipulation functions that extend beyond a basic ability to enter and change text, such as automatic generation of:

• batch mailings using form letter template and an address database (also called mail merging);
• indices of keywords and their page numbers;
• tables of contents with section titles and their page numbers;
• tables of figures with caption titles and their page numbers;
• cross-referencing with section or page numbers;
• footnote numbering;
• new versions of a document using variables (e.g. model numbers, product names, etc.)

Other word processing functions include spell checking (actually checks against wordlists), autocorrection, "grammar checking" (checks for what seem to be simple grammar errors), a "thesaurus" function (finds words with similar or opposite meanings), collaborative editing, comments and annotations, and support for images and diagrams.

A Text Editor is a type of program used for editing plain text files.Text editors are often provided with operating systems and software development packages, and can be used to change configuration files and programming language source code. There are important differences between plain text files created by a text editor and document files created by word processors such as Pages, Microsoft Word, and WordPerfect.

• A plain text file uses a simple character set such as ASCII to represent numbers, letters, and a small number of symbols. The only non-printing characters in the file that can be used to format the text are newline, tab, and formfeed.
• Word processor documents generally contain formatted text, such as enabling text to appear in boldface and italics, to use multiple fonts, and to be structured into columns and tables. These capabilities were once associated only with desktop publishing, but are now available in the simplest word processor.
• Web pages are created as plain text, with HTML tags to achieve formatting.

Word processors were developed to allow formatting of text for presentation on a printed page, while text produced by text editors is generally used for other purposes, such as input data for a computer program.

Q .5- What is Lossless and Lossy Compression technique ? Differentiate them?

Ans

LOSSLESS COMPRESSION / LOSSY COMPRESSION
No difference between the reconstruction and the original data. / Here The reconstruction differs from the original data.
This compression schemes is reversible so that the original data can be reconstructed. / This compression technique is irreversible in nature.
With Lossless compression technique the original file can be recovered exactly bit by bit after compression and decompression. / With Lossy Compression Technique the redundancy of the multimedia data at the cost of the changing or distorting the original file is done by which after decompression loss of data occurs.
During text Compression, Lossless Compression is used because it is required to have the exact copy of the original text file after decompression. / This compression technique is used for the compression of Sounds, Images and Videos.
Algorithm –

• Run- Length
• Huffman
• Arithmetic Coding

/ Algorithm –

• JPEG
• MPEG

Q. 6 Write a HTML to Program to make a Website Containing Following :

• Title
• Heading
• Background Color
• Paragraph
• Image ?

Ans-

<html>
<head>Football
<title>Welcome to Football Arena</title>
</head>
<body bgcolor = “RED”>
<h1>Barclays Premier League</h1>
<p<h3>In Barclays Premier League or English Premier League <br>
20 Teams Play 38 Matches by playing 2 Match each with a Team one Home and one Away.</h3</p>
<img src=”BPL.png” align=”center”>
</body>
</html>

Q.7 – Explain the different types of Frame used in MPEG 1 ?

Ans – The different types of frame used in MPEG 1 are as follow :

• I-Frame(Intracoded Frame) – These are the code without any reference to other images. In video sequence I-Frame are present at regular intervals in order to allow for he possibility of the contents of an I-Frame being corrupted during transmission. Compression ratio 10:1 to 20:1
• P-Frame(Prediction Frame) - They require information from previous I and/or P-Frame for encoding and decoding. P-Frame can be accused only after referenced I or P Frame has been decoded. The Number of P Frame in group of picture is generally limited as error in one frame may propagated in others. The number of frame b/w a P Frame and preceding I or P frame is called Prediction Span which may range from 1to 3. Compression ratio 20:1 to 30:1 .
• B-Frame (Bidirectional Frame) – It requires information from the previous and following I and/or P Frame for encoding and decoding. The highest compression ratio is attainable by using these frames. B Frames are never used as a reference for other frames. Reference frames must be transmitted first. The transmission order and display order differ. The I Frame must be transmitted first followed by the next P Frame and B Frame must be Transmitted.
• PB-Frame – A Fourth of Frame known as PB frame has been defined as it refers to the encoding to two neighboring P and B frames as a Single Frame. This enables and increases the frame rate without significantly increasing the resulting bit rate.
• D-Frame – A fifth types of frame known as D Frame is used in VOD applications. These are used to display the content when the user rewinds or fast forward through the movie and are ignored during the normal decoding of Frames. The D Frame are highly compressed and inserted at regular intervals throughout the Stream.

Q. 8 – What is Animation ? What is its Principle ? What are the different techniques used for Animation ?

Ans - Animation is the process of creating a continuous motion and shape change illusion by means of the rapid display of a sequence of static images that minimally differ from each other. The illusion—as in motion pictures in general—is thought to rely on the phi phenomenon. Animations can be recorded on either analogue media, such as a flip book, motion picture film, video tape, or on digital media, including formats such as animated GIF, Flash animation or digital video. To display it, a digital camera, computer, or projector are used. Animation creation methods include the traditional animation creation method and those involving stop motion animation of two and three-dimensional objects, such as paper cutouts, puppets and clay figures. Images are displayed in a rapid succession, usually 24, 25, 30, or 60 frames per second.

Principles of Animation :

• Animation is possible because of a biological phenomenon known as persistence of vision and psychological phenomenon called phi.
• An object seen by as person eye remains chemically mapped on the eyes retina for a brief amount of time after viewing.
• With animation, a series of images are changed very slightly and very rapidly, one after the other, seemingly blending together into a visual illusion of movement.

Different Animation Techniques used are as follow :

• Cell Animation – An animation technique made famous by Disney, uses a series of progressively different graphics on each frame of movie film.
• Tweening – It is an action that involves creating the frames to depict the action that happens b/w key frames. It is the process of calculating the no. of frames into b/w the key frames and the path that action takes.
• Path Animation – It allows you to assign an object to move along the course of a curve called a Path. It increases the complexity of an animation and provides motion, changing the location of an image along predetermined path during specified amount of time.
• Kinematics – It is the study of the movement and motion of Structures that have joints, such as a walking man. Animating a walking step is tricky as you need to calculate the position, rotation, velocity and acceleration of all the joints.
• Inverse Kinematics – It is the process in which you link objects such as hands to arms and define this relationships and limits,, they drag these parts around and let the computer calculate the result.