7 MAT Soln - Vidyalankarvidyalankar.org/.../SemV/CMPN/7_MAT_Soln.pdf · i) The phone can be used as...

1013/TY/Pre_Pap/Comp/MAT_Soln 193

Vidyalankar T.Y. Diploma : Sem. V

[CM/IF] Multimedia and Animation Techniques

Prelim Question Paper Solution

(i) Input Devices Output Devices i) The Electronic Pen i) Color Printer ii) Digitizer ii) Digital Camera iii) Pen Driver iii) Digital Camera iv) Pen Driver iv) CD-ROM

(ii) MPEG

The ISO committee which developed the MPEG standard is currently at work specifying a successor standard known as MPEG-2. The video component is targeted for bit rates in the range of about 2 to 15 Mbps. Additionally, MPEG-2 includes a number of new features with the intent of providing compatibility with existing standards (ISO = Indian Standard Organisation) Compatible transmission is conceptually similar to today's TV broadcasts, which can be received by both color and black and white television sets. The MPEG-2 encoding is intended to allow a single transmission to be received by a range of digital televisions, from small portable units that might only support NTSC resolution. Scalable digital video is critical to transmission over packet switching networks. As the load on the network increases, the transmitting node adjusts by decreasing the quality of the transmitted video. The audio encoding for MPEG-2 is also being extended. MPEG-2 audio will encode up to five full bandwidth channels (left, right, centre, and two surround channels), an additional low-frequency enhancement channel, and up to seven commentary or multilingual channels. Several improvements on the MPEG audio format are planned for lower sample rates. More recently, another digital video encoding standard effort known as MPEG-4 is underway. This new initiative is for very low bitrate coding of audiovisual programs, with particular application to mobile multimedia communications. Although MPEG-2 and MPEG-4 both use a DCT algorithm, it is anticipated that MPEG-4 will be based on a new algorithm, which, though computationally more expensive, results in significantly higher compression.

(iii) Telephone Authoring Systems

i) The phone can be used as a reading device by providing full text-to-speech synthesis capability so that a user on the road can have electronic mail messages read out on the telephone.

ii) The telephone can be used for voice command input for setting up and managing voice mail messages. Digitized voice clips are captured via the phone and embedded in electronic mail messages.

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iii) As the capability to recognize continuous speech is deployed, phones can be used to create electronic mail messages where the voice is converted to ASCII text on the fly by high-performance voice recognition engines or vice versa. eg. Say the name in mobile phone and the number gets dialed.

Attaching voice messages to electronic mail has been available for some time. Stored voice, however, is not an easy medium to use. When reading, we tend to spend more time on sections of text that are interesting while speeding through sections that have material of lesser interest. Stored voice, when played back, is played back with a mechanical cadence, and there is no opportunity to skip uninteresting sections. Furthermore, if a portion is not heard, it is lost; so speech requires constant attention. In the case of text, since text remains on the screen until the reader scrolls it, there is less pressure to pay attention. The voice messages seek more attention than text messages.

(iv) The Line Tool

You use the Line Tool to draw straight lines. To draw a line: i) Select the Line Tool from the Toolbox. ii) Place the pointer at a position where you want the line to start on the

Stage. The pointer changes to a plus sign. iii) Drag the pointer to draw a line of the length you need and then release

the mouse.

(i) Distributed Multimedia Systems The value of multimedia information and communication increases with the number of potential consumers of the information and users of the connectivity. It is widely expected that multimedia systems will provide large-scale access and distribution functions similar to the global telephone network and the Internet. The design of such systems is a distributed systems problem. However, distributed multimedia systems require special consideration of the requirements for continuous media. Supporting continuous Media The term continuous media refers to the temporal dimension of media such as digital video and audio, the data are a sequence of samples each with a time position. The timing constraints are enforced during playback or capture when the data are being viewed by humans. In addition to the time dimension, continuous media data are typically of large volume. These two factors impact the design of the core facilities of multimedia computing systems. Design of supporting continuous Media Factors : i) Time constraints ii) Volume of Data General purpose computing systems have been optimized for interactive use. File systems use layout policies that maximize use of disk space. Network protocols are designed for bursty traffic. Real-time operating systems exist, but flexible mechanisms for dynamically changing service levels are not available.

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Resource management, the key responsibility of the operating system, must now account for a new class of service in which time constraints and negotiable service levels must be satisfied. The existing interactive applications must continue to be serviced a well. For many continuous media applications there is flexibility in the required level of service. During heavy load, bandwidth requirements could be reduced by decreasing resolution of one or more continuous media streams. These types of scenarios require a negotiation process between application and local resource managers. The term quality of service (QOS) is used to represent the application requirements for a given resource. Standard QOS definitions have not been defined, but typical QOS parameters are minimum and maximum resolution, allowed error rate, and acceptable litter and delay bounds. The paradigm for resource management in the context of continuous media is based on the realization that some applications will require hard or deterministic guarantees of service. These strong guarantees can be given as long as certain factors such as load, buffer space, and schedule can be monitored or controlled. Other applications will need only statistical guarantee of some range of performance. Application which require minimal performance guarantees can be serviced on a best effort basis. For a given service class, the resource manager will perform an admissibility test when the resource is requested. The test determines whether a service schedule, which satisfies the requirements of the existing and new clients, can be constructed. If so, the request can be granted. If the request is refused, the resource manager might recommend lowerlevel service classes that might be available. The resource manager maintains a scheduling function in which currently admitted clients are serviced. During service cycles, the resource manager must monitor the application’s use of the resource so that unexpected overloading does not cause service deteriorated for other clients. Multimedia computing and communication systems provide mechanisms for endtoend delivery and generation of multimedia data that meet QOS requirements of applications. Distributed multimedia systems add capabilities such as global name spaces, client/server computing, global clocks, and distributed object management. Such facilities enable the sharing of resources over a larger population of users. With the technology for multimedia computing, distributed services will be feasible over a wide area using broadband networks.

(ii) Multimedia Object Servers

Multimedia systems consist of a number of information objects, including text, binary files, images, voice, and full-motion video. Many objects are shared by a number of users or, in the case of electronic mail (e-mail), are routed from one user to another. To achieve this functionality, the information objects must be stored on network resources accessible to all users who need to access them. These network resources are called Multimedia Object Servers.

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Types of Multimedia Servers i) Data-processing servers supporting RDBMSs and ODBMSs. ii) Document database servers. iii) Document imaging and still-video servers. iv) Audio and voice mail servers. v) Full-motion video servers. i) Data-processing servers are traditional database servers that contain

alphanumeric data. In a relational database, data fields are stored in columns in a table. In an object-oriented database, these fields become attributes of the object. In either case, indexing some fields or attributes is essential for fast access to data. The databases are designed for rapid searches of objects using one of the indexed fields or attributes. The database serves the purpose of organizing the data and providing rapid indexed access to it. The database management system can interpret the contents of any column or attribute for performing a search.

ii) Document database servers are used for electronic mail databases as

well as for document based information repositories. They are similar to conventional database storage in that they are also predominantly alphanumeric and may contain some indexed alphanumeric fields, They differ in that they contain special text fields that may be indexed within themselves using a hypertext engine. In addition, text fields in document databases that support hypermedia documents may have embedded or linked binary files, images, audio, and video objects.

iii) Document imaging and still video servers store and manage image and

still-video objects. An image object may be several tens to several hundreds of kilobytes in size. These objects may be in the form of basic operating-system-level files, or server files indexed in some manner for rapid location of the required image. In an object database, they may be indexed persistent objects. A file or an object may contain a one page image object (or file) or a complete document consisting of multiple pages. The server software may be set up with special caching mechanisms to speed up access to images.

iv) Audio and voice mail servers are used primarily for applications such

as voice mail, voice annotations, and voice help messages. Audio objects are large in size even in compressed form. Unlike other servers, audio servers may serve two different types of applications: traditional telephone based voice mail, and voice mail messages linked with the document-based messaging system.

v) Video servers are designed to manage very large objects. For example, a

10-second video object requires over a megabyte of storage. Besides providing the usual indexing functions, video servers are made intelligent to support the isochronous playback requirements for video objects by reserving network bandwidth; for example, in an ATM network this is achieved by reserving cells. Streaming playback is provided by video servers.

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Application Software The application software performs a number of tasks related to a specific business process. A business process consists of a series of actions that may be performed by one or more users. This series of actions is based on individual tasks that are strung together to perform a function that comprises a part or all of the business process. The basic tasks combined to form an application include the following : i) Object selection : The user selects a database record or a hypermedia

document from a file system, database management, system or document server.

ii) Object retrieval: The application retrieves (find/locates) the base object.

This base object may, for example, be a customer record or a memo depending on the nature of the application. The bas e object is displayed. Within the display of the base object may be some buttons that allow the user to display or playback associated multimedia objects.

iii) Object component display: Some document components are displayed

automatically when the user moves the pointer (mouse pointer or cursor) to the field or button associated with the multimedia object. e.g., popup-windows get displayed when mouse is moved over it.

iv) User initiated display: Some document components require user action

before play back/display. For example, an embedded video object requires the user to click on the button for the video object to bring up screen that simulates VCR controls. When the user pushes the play button, the video starts playing. e.g., window media player.

v) Object display management and editing : Component selection may invoke a

component-control sub-application which allows a user to control playback or edit the component object. The example of playing a video object is very applicable here. Example, When the user pushes the button for the video object, the sub-application for the display and playback of video object takes control and displays its own screen simulating VCR controls. The sub-application may allow cutting and pasting multiple video streams and soundtracks. Example, windows sound recorder.

(i) Pen Driver

A pen driver is a pen device driver that interacts with the digitizer to receive all the digitized information about the pen location. The pen driver in the windows for pen system consists of two drivers: an installable windows pen driver and a virtual driver. The digitizer hardware generates interrupts (signals) at the sampling rate. All interrupts go to the pen driver directly. If windows is running in standard mode, all the interrupts are received by the pen driver, which in turn builds pen information packets. If windows is running in enhanced mode, the interrupts go to a virtual driver. The virtual driver then builds the packets for the pen driver. The pen packet, you may recall, contains the x-y coordinates of the pen location and the pen status. The pen driver then sends the packets to the RC manager.

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(ii) Digitizer : It is a device that converts analog signals into digital signals.

Most digitizers are based on two types of technologies: electromagnetic and electro static. Electromagnetic digitizers contain an x-y grid of wires. When the pen or digitizer mouse, which contains a magnetic coil, is brought near the grid, it induces a voltage. The voltage generated depends on the position of the pen over the grid.

Electrostatic technology : The pen is brought near the screen, the voltage is identified and the x-y position is encoded.

Synchronization Synchronization is the coordination of events in time, and various mechanisms and formalisms for synchronization have been developed, ranging from lowlevel hardwarebased techniques to abstractions for concurrent programming languages. Systems using continuous media data do not require fundamentally new synchronization primitives, but do require consideration of two aspects of multimedia applications. i) Synchronization events have realtime deadlines, and ii) Failure to synchronize can be handled using techniques such as frame

repetition or skipping such that the application can still continue to execute. For example, an application might be concerned with synchronization points such as the beginning and end of a video segment, the presentation system might be concerned with frame synchronization, and the network over which the video is transmitted might be concerned with packetlevel or celllevel synchronization. Consequently, the representation of synchronization requirements might vary from layer to layer as well as between different applications. e.g. Application on which video is played frame by frame on “You Tube”, over internet where video is transmitted as packets. Therefore real time gets affected.

Information Access Types of Information Access i) Direct ii) Indexed iii) Random Selection iv) Guided Tour v) Browsing

i) Direct : Direct information access requires that the user have knowledge of the specific object about where the object is stored and its contents that needs to be accessed.

Digitizer Interrupts

Pen Driver Packets

RC Manager

Pen used on screen

Pen used as mouse

Message Message

Display Manager

Windows

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ii) Indexed : Indexed objects include Index Markers in the data object which provide easy accessibility of data. If the object ID of the object is an index entry that resolves to a filename on a specific server and disk partition, then the information access mechanism is an indexed mechanism.

iii) Random Selection : In this form of information access, the user can pick

one of several possible items. iv) Path Selection or Guided Tour : In a guided tour, the application guides the

user through a predefined path across a number of objects and operations. v) Browsing : We have already seen that browsing is useful when the user

does not have enough knowledge about the object to access it directly.

The Toolbox The Toolbox is divided into four sections: Tools : Contains tools for selecting, drawing, and editing shapes or images. View : Contains tools that help you see an image in different modes. Colors : Contains colors that are currently used in a shape. Options : Contains modifiers for the various tools. The modifiers appear only

when a tool is selected in the Tools section. Panels You use panels to modify the characteristics of images, such as changing the height and width, selecting colors, and changing text settings. In addition, you can also move, group or separate the panels themselves by dragging the tab that contains the panel name.

If you need more space in your window while working, you can hide a panel. To do so, double-click the title bar and the panel will minimize or maximize. Right click the panel, choose Close Panel to close it.

After you get comfortable with Flash, you might find, that you use some panels frequently. Once that happens, close the panels you don't use, align your favorite panels, and then save them by choosing Window Save Panel Layout to create a panel set. You can open your panel set by choosing Window Panel Set and then name you gave it.

Joint Photographic Experts Group (JPEG) Compression JPEG is a compression standard for still color images and grayscale

images (also known as continuous tone images). It was designed to provide a common methodology for compression of

continuoustone images. This standard allows generation of compressed files for grayscale images,

photographic images and still video. The objective are i) The design should address image quality in the range where visual fidelity is

very high. The encoder can be parameterized to allow the user to set the compression or quality level.

ii) The compression standard should be applicable to practically any kind of continuous-tone digital source image and should not be restricted by

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dimensions, color, aspect ratio, class, imagery or scene contents or range of shades or colors.

iii) It should be scalable from completely lossless to lossy ranges. iv) It should provide for progressive encoding (usually achieved by multiple

scans). In this, image is decompressed so that a coarser image is displayed first and is filled in as more components of the image are decompressed to provide finer version of the image.

v) They should provide the option of lossless encoding so that images, if needed, can be guaranteed to provide full details at the selected resolution when decompressed.

RTF Rich-Text Format TIFF Tagged Image File Format

Scaling Scaling is an obvious feature since users are quite used to changing window sizes. When the size of the video window is changed, scaling takes place. If the video is placed originally at 640 480 pixels (a standard VGA size), it is possible to see it as a fullscreen picture on a VGA screen, or as a smaller picture on a Super VGA or an 8514A screen. Monitors with higher resolutions will show it as an even smaller picture. A 1280 1024 pixel resolution monitor would show it in a quarter-screen-sized window. When the window is smaller than the screen size, users expect to be able to resize the video window. Making the video window smaller is easy—requires dropping some of the pixels, just as in the case of images, for scaling to the new size. When the window is to be made larger, the issues are more complex. While in the case of document images, the scan resolution is usually much higher than available display resolutions and scaling down is the norm, in the case of video that may not be so because VCR resolutions are not quite as high as Super-VGA monitors. Enlarging an image beyond available pixels implies creating new information based on estimation or projections from other surrounding pixels. While not as common, this is the approach used by some application developers. Panning

Panning across a video window implies that only a part of the video is visible in the window. Panning allows the user to move to other parts of the window. Panning is useful in combination with zooming. That is, only if the video is being displayed at full resolution and the video window is not capable of displaying the entire window is panning useful. Panning is therefore useful only for video captured using very-high -resolution cameras, such as the professional cameras used for commercial movies.

Original Pic Scaled smaller Scaled larger

Original Pic. Panning Video Scene 1 Scene 2 Scene 3

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Zooming Zooming implies that the stored number of pixels is greater than the number that can be displayed in the video window. In that case, a video scaled to show the complete image in the video window can be paused and an area selected to be shown in a higher (or full) resolution within the same video window. The video can be played again from that point either in the zoomed mode or in scaled-to-fit-window mode.

Lossless compression By defination, in lossless compression, data is not altered or lost in the

process of compression or decompression. Decompression generates an exact replica of the original object. Text compression is an example of lossless compression. They contain

repeated sequences of characters. Compression techniques, usually reducing repeated characters to a count, are used for saving disk space.

When decompressed (unzipped), the repeated characters are reinstated. There is no loss of information in this method. Text Compression

Similarly, image and gray scale images contain information that is repetitive in nature, that is, a series of successive pixels may be of same type. Image Compression

This repetitive nature of text, sound and graphic images allows replacement of repeated strings of characters or bits by codes.

But when there is lack of repetitiveness in information this technique do not reduce size to acceptable level. e.g. motion pictures, colour images, animated images etc.

This technique have been able to achieve reduction in size in the range 1/10 to 1/50 of the original uncompressed size without visibly affecting image quality.

The following are some of the commonly accepted lossless standards. i) Packbits encoding (Runlength encoding) : Makes codes for each string. ii) CCITT Group 31D Compression : For Black and White Images only iii) CCITT Group 32D Compression : For all images with Low-Resolution (With

‘K’ Factor) iv) CCITT Group 42D Compression : For all images with High Resolution

(without ‘K’ factor) v) Lempel Ziv and Welch algorithm (LZW) : According to algorithm.

Orchestration or MetaScheduling Each resource manager includes a scheduling function which orders the current requests for servicing so as to meet the required performance bounds. For example, a continuous media file system schedules storage system access operations, and the network layer schedules traffic to the transport layer. An application requires the coordinated operation of these scheduling functions if endtoend performance bounds are to be met. An approach to coordinating resource scheduling of the various systems is to add a layer between the application and the resource managers is called orchestration or Meta-scheduling.

Zoomed image

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CCITT Group 32D compression : It is also known as modified run length encoding. It is commonly used for software based document imaging systems and facsimile. The compression ratio is between 10 and 20%. The scheme of decompression is more easy. It combines one dimensional coding scheme with a two dimensional coding

scheme. Twodimensional encoding offers higher compression because statistically,

many lines differ very little from the lines above or the lines below. This scheme uses a “K” factor where the image is divided into several groups

of Klines. The first line of every group of K lines is encoded using the CCITT Group

31D method. This first line becomes the reference line for the next line, and a two dimensional

scheme is used along with one dimensional scheme to encode the rest of the scanlines in the group of K lines.

The fist line in group can be used for synchronization which can be used to correct the error occurred in transmission as the 1st line is the reference line for the whole group.

The 2D scheme uses a combination of additional codes called vertical code, pass code and horizontal code to encode every line in the group of K lines. There is only one type of pass code with a value of 0001. Horizontal cod also has only one type, with a value of 001. There are seven types of vertical code, and the values depend on the position difference between the changing pixel in the reference line and the changing pixel in the coding line.

EOL (End of Line) Markers are placed before start of compressed data. Fillers are used for scanlines and at end of the file.

NO EOP (End of Page) Markers at the end of compressed data. Advantages The implementation of the K factor allows errorfree transmission. It is worldwide facsimile standard, also accepted for document imaging

applications. Due to two dimensional nature, the compression ratios achieved with this

scheme are better than CCITT Group 31D.

Disadvantages Compression is less compared to CCITT Group 4.2D Compression. It is complex and relatively difficult to implement in software.

Line1 Line2 Line3

so on

Line 1

K-line group

K-line group

Ref. Line

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We use the Eyedropper Tool to copy the stroke or fill color of one shape to another shape. To use this tool to copy the stroke color: i) Select the Eyedropper Tool and place the pointer on the outline of the shape

whose stroke color you want to copy. The shape of the pointer changes to an eyedropper with a pencil at its side.

ii) Click the stroke of the shape. The shape of the pointer changes to an ink bottle.

iii) Click the outline of the shape to which you want to apply the stroke color. To use this tool to copy the fill color: i) Select the Eyedropper Tool and place the pointer inside the shape whose

fill color you want to copy. The shape of the pointer changes to an eyedropper .with a paintbrush at its side.

ii) Click the fill of the shape. The shape of the pointer now changes to a paint bucket.

iii) Click inside the shape to which you want to apply the fill color.

(i) Viewing and Editing Shapes You can view a document at different levels of detail by using the Zoom Tool or the Hand Tool. You can transform an existing shape to a new shape by using the Arrow Tool or the Eraser Tool. Viewing Shapes You can view a document in three modes : Zoom In, Zoom Out, and Magnification. You can use Zoom In and Zoom Out to view a specific part of a document in magnified or reduced form. You can use Magnification to view the entire document in a magnified form.

When you use a viewing tool, only the display of the shape is altered and not its dimensions or file size. You can select magnification levels ranging from 25% to 800%, or you can specify your own magnification level. The percentage of a shape's actual size appears in the Zoom box. The Zoom Tool While creating a shape, you can have a closer look at it by zooming in so that you can work on the details. You can then reduce the size of the shape to view the entire document by zooming out. To do this, you use the Zoom Tool. When you select the Zoom Tool, the Enlarge and Reduce modifiers appear in the Options section of the Toolbox. By default, the Enlarge modifier is selected.

You can zoom into or magnify a shape by selecting the Zoom Tool and then clicking the shape. To reduce the size of the shape, select the Reduce modifier and then click the shape.

The Hand Tool After you have zoomed in on a shape, you can see only some parts of the document. However, you can move the Stage to view the other components of the document. You can use the Hand Tool for moving the Stage. To move the Stage, select the Hand Tool and drag the Stage in the direction you want to move it.

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Fig.: The Shape of a Leaf Selected with the Lasso Tool

Editing the Curves and Corners of a Shape You can change the appearance of basic shapes by using the Arrow Tool and Free Transform Tool. For example, you can create the shape of a mango from an oval by pulling one of its sides inward, or you can create the shape of a diamond by editing the corners of a rectangle by using the Free Transform Tool. To edit the curves and corners of a shape: i) Select the Free Transform Tool and place the pointer over the line

segment that you want to reshape. ii) A curve or a corner appears at the tail end of the pointer indicating that

you can modify it. iii) Drag the pointer to create the shape of your choice.

Arrow Tool and Free Transform Tool Modifiers When you select the Arrow Tool, its modifiers such as, Snap to Objects, Smooth, and Straighten appear in the Options section of the Toolbox. By default, the Snap to Object modifier is selected. The other modifiers are disabled if no shape is selected on the Stage. Irregular Selections using Lasso Tool You can also make a freeform marquee selection to select specific shapes from a cluster of shapes. For example, you want to select a single leaf from a bunch of leaves as shown in the following figure. Here, you cannot use the rectangle marquee selection. You use the Lasso Tool to make freeform selection. To make a freeform marquee selection: i) Select the Lasso Tool. The shape of the pointer changes to a lasso. ii) Place the pointer at a position where you want the selection to start, iii) Drag the pointer to draw a line around the shapes you want to select. iv) Complete the selection by connecting the starting and ending points of

the line. Otherwise, Flash automatically draws a straight line from the point where you left, to the starting point.

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(ii) Object Display/Playback Issues Each object type has some additional requirements to address common features expected by users and to provide users with some special controls on the display/playback of these objects. We will address some of these issues for image, audio, and video objects here.

Image Display Issues Images are stored in compressed form. Images scanned by high-quality scanners are scanned at 400 pixels/inch or higher resolutions. A typical image at this resolution requires a screen resolution of 400 pixels/inch or approximately 3600 4400 pixels. Since most monitors for computer use are limited to 1280 x 1024, the image is scaled down. i) Scaling : Image scaling is performed on the fly after decompression. The image is

scaled to fit in a user- (or application-) defined window at the full pixel rate for the window. In other words, if the image is scanned at 3600 4400 pixels and the full resolution for the window is only 600 440, the image is being scaled by a factor of 6 x 10, that is, 60 times. This factor is changed as the window size is changed. This factor will also be different for the same window size for higher-resolution monitors.

ii) Zooming : Zooming allows the user to see more detail for a specific area of the

image. For example, zooming helps in seeing greater detail about a picture, reading dollar amounts in a form, or even checking a signature. At full resolution of 3600 4400, a small window of 1.5 inches 1 inch out of a standard 8.5 inch 11 inch document can be seen at full resolution in a 600 x 400 pixel window. In effect, the zoom factor is 60%. Users can zoom by defining a zoom factor (e.g., 2:1, 5:1 or 10:1). These are set up as preselected zoom values.

iii) Rubber Banding : This is another form of zooming. In this case the user can use a mouse

to define two corners of a rectangle. The selected area can be zoomed. iv) Panning :

Panning

Image Display Issues

Scaling Zooming Rubber Banding

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Panning implies that the image window is unable to display the full image at the selected resolution for display. In that case the image can be panned left to right or right to left as well as top to bottom or bottom to top. Panning is useful for finding detail that is not visible in the full image.

(iii) The search operation is very similar in that the primary function is to find an

object (record) in response to a query. However, in the case of distributed multimedia objects, searching may involve additional transactions to locate a copy of the required object and to obtain a copy from a remote server onto a local server for further client operations. It is further possible that the query may require special programs to scan the multimedia object to recognize components in it that may be required or set up as the starting point. For example, in JPEG and MPEG compressed audio and video files, can be used to jump to successive scenes and start retrieval at a specific scene.

The browse operation is not very common in relational databases except where specifically programmed in an application. In information and document databases, browse function is much more useful. The browse function may be required not only to retrieve attribute information about the objects but also render frames of the object contents. For example, a browse function may allow users to scan key frames in stored videos. Key frame detection is an integral part of the browse feature in such systems.

(iv) The Role of Standards

The goal of universal access and distribution using distributed multimedia systems technology requires a significant amount of interoperability of the components and exchanged information. The interoperability requirement depends upon standards for communication, information formats, and system service. The development of standards for multimedia technology is an area of great activity. The framework presented here provides an overall picture of the development of distributed multimedia systems from which a system architecture can be developed. The framework highlights the dominant feature of multimedia systems : the integration of multimedia computing and communications, including traditional telecommunications and telephony functions. Lowcost multimedia technology is evolving to provide richer information processing and communication systems. These systems, though tightly interrelated, have distinct physical facilities, logical models, and functionality. Multimedia information systems extend the processing storage, and retrieval capabilities of existing information systems by introducing new media data types, including image, audio, and video. These new data types offer richer and more accessible representations for many kinds of information. Multimedia communication systems extend existing pointtopoint connectivity by permitting synchronized multipoint group communications. Additionally, the communication media include timedependent visual forms as well as computer application conferencing.

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(i) RAID (Reduced Array (Data) of Inexpensive Disks) A number of different RAID schemes have been developed to address

needs. Following lists these key objectives for using RAID systems: i) Hot backup of disk systems (as in disk mirroring) ii) Large volume storage at lower cost iii) Higher performance at lower cost iv) Ease of data recovery v) Speed Improvement due to data Striping Following six levels are present in RAID.

RAID level O – Disk striping : It has multiple drives connected to a single disk controller. Data is striped

to spread segments of data across multiple drives in block data sizes ranging from 1 to 64 kbytes.

By spreading data across drives, disk striping provides a high transfer rate for applications that write or retrieve blocks of data. The data being written to disk is broken into segments. The first segments is written to first drive, second segments is written to the last drive, the process is respected, beginning with the first drive.

RAID level 1 Disk mirroring Not only is data striped across multiple physical drives as in RAID level

O, but also, the disk mirroring causes two copies of every file to be written on two separate drives. In this method, each main drive also has a mirror drive. These drives are connected to a single disk controller.

Disadvantages Expensive Write operation takes more time. RAID level 2 – Bit interleaving of data It contains arrays of multiple drives connected to a disk array controller. Data, written one bit at a time, it bit interleaved across multiple drives

and multiple cheek disks are used to detect and correct errors. The disk

Controller

Disk 1 Disk 2 Disk 3 Disk 4

Segment 0 1 2 3 4 5 6 7 8 .. .. ..

Controller

Seg.0 Seg.0 Same seg. written to

both

Main drive Mirror drive

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drives operate in parallel with their spindles synchronised and the drive array appears as one drive to the host.

Advantages Ability to handle very large files High level of data integrity and reliability due to the error detection and

error correction features. If one data drives fails in system, data can be reconstructed from error correction drives. If error correction drive fails, then error correction code can be reconstructed from data drives.

Very high performance. Disadvantages It requires multiple drives for error correction and is expensive approach to

data redundancy. Each sector on a drive is associated with sectors on other drives to form

a single storage unit. It takes multiple sectors across all data drives to store even just a few bytes, resulting in waste of storage.

RAID level 3 Parallel Disk Array System data is also bit or byte interleaved across multiple drives. RAID

level 3 is more efficient than RAID level 2 because parity bits are written into the data stream and only one parity drive is needed to check data accuracy.

The difference between RAID2 and RAID3 is that RAID3 employs only parity checking instead of full leaning code error detection and correction, so requires only one parity drive. During data writes a parity bit is generated and written to the parity drive, during data reads parity checking takes place. This process is called on the fly parity generation and parity generation and parity checking.

Advantage Good data integrity at high performance levels. Cost effective

A1

B1 A2

B2 A4

B4 A3

B3 A5

B5 A5

B5

Array controller

Host adapter

A1 A5 bit interleaved across drives Diagram RAID level 2

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Disadvantage : Not suitable for small file transfers RAID Level 4 – Sector inter leaving Multiple data drives and single dedicated parity drive. Data is interleaved at sector level. Write involves writes to the data drive and the parity drive for each

sector. Since the parity drive is dedicated, only one write can take place at any time.

One parity drive for each sector. Advantages : Ideal for large data transfer. RAID level 5 – Block interleaving Data is block interleaved. Do not use dedicated parity drive. Parity drives are spread across multiple drives. Advantage : High performance Disadvantage : Cost of implementing the solution. Does not perform well with large block sizes.

(ii) QOS Architecture

Quality of service (QOS) is used in the OSI reference model to allow service users to communicate with network service regarding data transmission requirements. In OSI, QOS is specified using a number of parameters which can be grouped into three sets : single transmission, multiple transmission, and connection mode. QOS parameters include transit delay, residual low error rate, and through output. For connectionoriented service, the QOS parameters required by the network service user are specified in the request

B1

B6 B11

PA

B7 B12

B3

B8 B14

B2

PB B13

B4

B9 PC

B5

B10

B15

Array controller

Host adapter

Organization of disks in RAID level 5 disk arrays.

B1

B6 B2

B7 B4

B9 B3

B8 B5

B10 Pa

Pb

Array controller

Host adapter

Each block is written in to different drive

Parity bits

Block

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for connection. The network service provider determines whether the requested service parameters can be provided. If so, the request is forwarded to the called party, possibly with different parameter values. The called party can either accept or reject the request. If not, the network provider will reject the request. If the connection is confirmed, the actual QOS parameter values are returned to the network user. The QOS parameters are passed down the OSI stack during the connection establishment phase for negotiation and configuration of the connection. Some parameters are only available to the upper levels. For connectionless service, the QOS parameters are passed with the data transmission request. i) Tightly controlled : The traffic patterns of a stream are preserved at each

switching point in the network. This simplifies computation of performance bounds for admission tests, but the queuing discipline can be complex to implement and the network can be significantly underutilized.

ii) Approximate : The traffic patterns of data sources are approximated using relatively simple models at both the network edge and internal to the network. Because the models are simpler, the approximate approach is more suited to implementation of a realtime admissibility algorithm. Further, because worstcase traffic assumptions are not made at the internal switching points, network utilization can be improved. However, the models are approximate and, as yet, do not provide formal deterministic guarantees of service.

iii) Bounding : A bound (statistical or fixed) is specified for traffic on the edge of the network. Bonds are recomputed for each session along the route of the session. Issues in the use of this approach include the tightness of the resulting bounds and the extent to which traffic can be modelled by the statistical bounds.

iv) Observationbased : Measurements of actual data sources are used to define different service classes. An arriving call specifies its expected service class. The current set of calls and the service class assignments are used to determine admissibility. The dependence of this approach on traffic measurement parameters, number of active calls, and the size of the network requires further study.

Application Layer

Orchestration Layer

Multimedia Mechanism Layer

(a) Distributed Computing

Orchestration Layer

Communication Subsystem

(b)

Orchestration Layer

Generation Function

Presentation Function

Transport Function

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WORM Optical Drives WORM (Write Once Read Many) optical disk technology records data using

a high power laser to create a permanent burnt in record of data. Low Cost but slower than magnetic drives. The laser beam makes permanent impressions on the surface of the disk by

creating pits so that once the information is written, it cannot be written over and cannot be erased. Hence name WORM.

A 12-inch WORM Drive stores more than 6 GB of data. Recording : The input signal is fed to the laser diode. The laser beam from laser diode is modulated by the input signal, which switches the laser beam on and off. When the laser beam is switched on, it strikes the three recording layers. The laser beam is absorbed by the bismuth – tellurium layer (Bi2Te3) and head is generated within the layer, which is now the recorded area. Reading : During reads, a weaker laser beam then the unite laser beam is focused onto the disk. The laser beam is not absorbed due to the reduced power level instead, it is reflected back. The beam splitter mirror and lease arrangement sends the reflected beam to the photo detector. The photo sensor detects the beam and converts it into the electrical signal, which is read and understood by the computer. The WORM drives have long-shelf life i.e., they do not get easily destroyed. It provides Optical Disk Library call jukebox. Optical Drives are slower than Magnetic drives.

Protective layer

Reflective layer

Antimony-selinide Sb2se3

Bismuth-telurium Bi2Te3

Antimony – selenide Sb2Se3

Polycarbonate substrate

Recording layer

Coat of leaguer to prevent oxidation

Aluminium alloy or gold to increase reflectivity of recorded surface

Disk

Detector Polarized

beam splitter

Laser diode Input signal

Beam splitting on WORMs for disk writes.

5. (a)

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WORM Drive Application On-line catalogs, such as for an automobile parts dealer. Large volume distribution. Transaction logging, such as for a stock trading company. Multimedia archivals like CD, DVD.

Multimedia Authoring Systems Authoring systems for multimedia applications are designed with the following two primary target users in mind: professionals who prepare documents, audio or soundtracks, and full-motion video clips for wide distribution; and average business users preparing documents, audio recordings, or full-motion video clips for stored messages or presentations. The key differences between the uses of these two types of authoring systems for creating multimedia objects pose different sets of requirements for the authoring systems. Similarly, the human engineering issues for these two types of users are different. Ad hoc users of an authoring system use it to create hypermedia documents or presentations and to communicate with other users of desktop video conferencing and store-and-forward messaging. These users require authoring tools that are simple to use. Performance is not as great a concern for them as it is for users of professional authoring tools. A more cryptic user interface is acceptable for professionals (whose primary job is to prepare hypermedia documents) if it provides faster key-strokes and a more efficient user interface. Professional authors of hypermedia documents need more comprehensive and flexible editing for tools for hypermedia document creation and editing. Design Issues for Multimedia Authoring : Display resolution Data formats for captured data Compression algorithms Network interfaces Storage formats Display Resolution : Resolution defines quality of data, it is measured in dpi or ppi. In any enterprise, users have a wide variety of display systems and screen resolutions. Rather than restricting all users to specific display resolutions, it is usually better to standardize interfaces at various acceptable resolutions and for different applications. In this manner, it is possible to ensure that all users can interact at the right levels. i) Level of standardization on display resolutions ii) Display protocol standardization iii) Corporate norms for service degradations iv) Corporate norms for network traffic degradations as they relate to resolution issues

Resolution : Quality Resolution : Quality

5. (b)

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File Format and Data Compression Issues : The various data formats for image, audio, and full-motion video objects. The variety of data formats is so great that the ability to control them is not very good in most cases. Rather than standardize on a single format, it is better to select a set for which reliable conversion application tools are available. This allows users to use a large number of applications, and move back and forth among them quite smoothly. In a sense, this is the same kind of problem one faces with word processing systems or graphics applications. i) Compression type ii) Estimated time to decompress and display or play back the object (for audio

and full-motion video) iii) Size of the object (for images or if the user wants to download the object to a

notebook) iv) Object orientation (for images) of quality. v) Annotation markers and history (for images and sound or full-motion video) vi) Index markers (for sound and full-motion video) vii) Date and time of creation viii) Source file name ix) Version number (if any) x) Required software application to display or playback the object.

LAYERS To convert a fixed text block into an extending text block, double-click the square at its upper-right comer. To convert an extending text block to a fixed text block, drag the circle at its upper-right corner in any direction. Scrollable Text Block Let's say you have a large block of text you need to fit in a small area but you still want it to be readable. One solution might be to use a scrollable text block. What you do is create a text block, add the text, and format it. Next, you resize the text block and move it to the correct location. Now, you attach a scroll bar to the text block so that more text will be displayed when the user scrolls down. To create a scrollable text block: i) Change the text type to Dynamic Text or Input Text, in the Properties panel. ii) From the Line type drop list, select Multiline. iii) Right-click the text block and choose Scrollable. iv) From the Components panel drag and drop Scroll Bar.

You can identify a scrollable text block by the solid black square that appears in the lower-right corner as shown in the following figure:

5. (c)

We bring you a rich heritage of exotic spices from all over the world. You can reach us

at out kiosks set up in special grocery stores, in various

parts of the country.

Fig.: A Scrollable Text Block

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Changing the Order of Layers To change the position of a layer, select it, and drag it above the layer over which you want to place it. Merging Layers You can merge layers when you want all the components on those layers to act as a composite image. You cab merge as many layers as you want. To merge layers: i) Select the layers whose contents you want to place in another layer. The

contents of the selected layers appear selected on the Stage. ii) Choose Edit Cut. The contents of the selected layers disappear from the

Stage. iii) Select the layer in which you want to place the contents. iv) Choose Edit Paste in Place. The contents of the layers merge and

reappear on the Stage. Deleting layers When you delete a layer, it's content is removed from the Stage. To delete a layer, click the Delete Layer button or drag the layer to the Delete Layer button at the bottom of the layers list. You can also right-click the layer arid choose Delete Layer. Once text has been added, you format it by changing its alignment to left, right, or center, or justify. Alignments control the way the text is positioned relative to the left and right margins of the Stage. You can change alignments by using either one of the following two ways: Choose Text Align, and choose an alignment option from the submenu. Select the text block, and in the Properties panel, click an alignment button. Skewing and Scaling Text You can increase the size of the text block by using the Free Transform Tool. To increase the size: i) Select the text block. ii) Click the Free Transform Tool. iii) Use the Scale modifier. You can also rotate and skew the text by using the Rotate and Skew modifier. These options help you to create mirror images of text. Breaking Text Apart You can manipulate individual characters of the text by converting them to vector shapes. To do so, you need to break apart the text. To break apart text, select the text block and choose Modify Break Apart. To lock all the layers except the selected layer, right-click the selected layer and choose Lock Others. To unlock these layers, right-click the selected layer and choose Show All. To lock all the layers in a document, click the Lock/Unlock All Layers button, as shown in the above figure.

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Fig. : A Hidden and Visible Layer

Hiding Layers Hiding a layer hides it's content from the Stage. You cannot edit or print the content of a hidden layer. You hide a layer when you want to modify a layer below it. To hide a layer, you can either: Click the dot in the Eye column next to the layer name in the layers list. Open the Layer Properties dialog box and clear tile Show option for that layer.

A cross appears in the Eye column for a hidden layer, as shown in the following figure. Also, the content of the layer disappears from the Stage. To show a hidden layer, you can either: Click the cross icon in the Eye column next to the layer name in the layers list. Open the Layer Properties dialog box and check the Show option for that layer. To hide all the layers except the selected layer, right-click the selected layer and choose Hide Others. To unlock these layers, right-click the selected layer and choose Show All. To hide all the layers in a document, click the Show/Hide All Layers button. Once you've placed content on a layer, a name like Layer 3 doesn't help much, instead, you'll want to change the layer's name to something more meaningful In addition, you might want to prevent the layer from being modified. Therefore, you can both lock that specific layer and then continue with editing content on other layers, or you can hide the layer so that it is no longer visible. Renaming Layers To rename a layer: Choose Modify Layer to open the Layer Properties dialog box, and in the

Name box, specify the name. You can also right-click a layer and choose Properties to open the Layer Properties dialog box.

Double-click the layer, type the new name for the layer, and press Enter. Locking Layers Locking layers prevents you from making unintentional changes in the contents of the layers; When you lock a layer, a lock icon appears in the Lock column of the layers list, as shown in the following figure.

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After locking a layer, if you select any of the Line, Oval, Rectangle, or Pencil tools and move the pointer on the Stage, the pointer changes to a pencil with a circle having a line across it. This indicates that the layer is locked and not able to be edited. To lock a layer, you can either: Click the dot in the Lock column next to the layer name in the layers list. Open the Layer Properties dialog box and check the Lock option for that layer. To unlock a layer, you can either: Click the lock icon in the Lock column next to the layer name in the layers list. Open the Layer Properties dialog box and clear the Lock option for that layer. The first step in creating a frame-by-frame animation is to create the image with which you want to start the animation. To complete the animation, you add the modified versions of the image to the keyframes that you insert in the Timeline.

The Brush Tool We use the Brush Tool to add brush-like strokes to an image, as shown in the following figure. After you select the tool, you can change the size and shape of the brush by selecting the various options for the modifiers available in the Options section of the Toolbox.

6. (a)

Fig.: A Locked and Unlocked Layer

Fig.: The Use of the Brush Tool to Add Special Effects to an image.

Brush strokes applied to give the effect of background

Brush strokes applied inside a shape Vidy

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Custom Gradients You can use the Color Mixer panel to create a custom gradient. To create a custom gradient: i) From the Fill style list, select a gradient type. There are two types of

gradients: Linear: In this; the transition of the colors is in a horizontal direction

across a shape. Radial: In this, the transition of colors occurs in a circular form in the

shape. ii) The gradient bar, gradient slider, and the Gradient sample box appear

below the Fill style list. You can adjust the position of the various sliders by moving them. As you move the sliders, a new gradient is created and a preview of the new gradient appears in the Gradient sample box.

iii) Display the Options menu and choose Add Swatch. The gradient is added to the Fill Color palette.

Custom Line Styles To create custom line styles: i) Choose the Line Tool. ii) Choose Window Properties, to open the Properties panel. iii) In the Properties panel, click Custom. The Stroke Style dialog box appears.

Distributed Client-Server Operation While the client-server architecture has been used for some time for relational databases such as Sybase and Oracle, multimedia applications require functionality beyond the traditional client-server architecture. Most client-server systems were designed to connect a client across a network to a server that provided database functions. The clients in this case were custom-designed for the server. Furthermore, it was assumed that the client-server link was firmly established over the network, and that there was only one copy of the object on the specified server. An important advantage of several custom views is the decoupling they provide between the physical data and the user. The physical organization of the data

6. (b)

Fig.: The Color Mixer Panel

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Fig.1: Client-server custom views in large database

End

can be changed without affecting the conceptual schema by changing the distributed data dictionary and the distributed repository. Similarly, logical independence is achieved, and the conceptual schema can be changed without affecting the external views Distributed database technology plays an important role in multimedia systems. In traditional relational databases operating primarily with symbolic data, real-world knowledge is abstracted into a data model. Knowledge about relations among entities is then stored in the database in a data dictionary. The data dictionary provides the data linkages for performing queries against the database. In multimedia databases, we have a combination of real-world data objects as well as projections in images, sound, and video. While raw data such as numbers or text fields are meaningful to the database, multimedia objects are not. The database must assign some form of identification and an understanding of the data. Furthermore, on retrieval database objects may need special processing before being rendered on user screens. Clients In Distributed Workgroup Computing Clients in distributed workgroup computing are the end users with workstations running multimedia applications. These client systems interact with the data servers in any of the following ways: i) Request specific textual data ii) Request specific multimedia objects embedded or linked in retrieved

container objects iii) Require activation of a rendering server application to display/playback

multimedia object iv) Create and store multimedia objects on servers v) Request directory information on locations of objects on servers

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Servers in Distributed Workgroup Computing Servers, in addition to the basic function of storing data objects, provide a number of other functions, including those listed as follows : i) Provide storage for a variety of object classes. ii) Transfer objects on demand to clients. iii) Provide hierarchical storage for moving unused objects to near-line (optical

disk libraries) or off-line (optical tape libraries) media. iv) System administration functions for backing up stored data. v) Direct high-speed LAN and WAN server-to-server transport for copying multi-

media objects.

Public Switched Network During the past decade, the telecommunication industry had developed a roadmap for the evolution of digital switched communication services based on ISDN (Integrated Services Digital Network). ISDN standardizes connection interfaces, transmission protocols, and services. More recently, initial recommendations for Broadband ISDN (BISDN) have been adopted. Unlike ISDN, which is a digital circuit switching network, BISDN uses cell relay or asynchronous transfer mode (ATM). ATM is suitable for every high speed switching of fiber optic transmission networks. BISDN will be upwardly compatible with ISDN, leading to a global highspeed network suitable for highspeed multimedia traffic with common service definitions throughout the switching components. ISDN = Integrated Services Digital Network = Digital Service Switching Network BISDN = Boradband ISDN = ATM (Asynchronous Transfer Mode)

I pictures are intracoded, meaning that they are coded independent of any

other picture. An I picture must exist at the start of any video stream and also at any random-access entry point is the stream.

B pictures are interpolated pictures, which are coded by interpolating between a previous and a future I or P picture. This process is sometimes referred to as bidirectional prediction.

6. (c)

6. (d)

CATV

BROADCAST SATELITE

INTERACTIVE VIDEO DEVICES

CELLULAR LAPTOPS

CELLULAR PHONE

PUBLIC SWITCHED NETWORK

DIGITAL PBX

MAN/WAN

DIGITAL PBX

MAN/WAN

WIRELESS LAN ISDN/BISDN

WIRELESS LAN

PDA

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1013/TY/Pre_Pap/Comp/MAT_Soln220

An I picture requires the most data; it is similar to a JPEG image. It is structured into 8 8 blocks that are DCT coded, quantized, and statistically encoded, A P picture requires about one-third of the data of a I picture; it consists of 16 6 macroblocks, which are DCT coded motion correction values. A B picture takes 2:1 to 5:1 less data than a P picture; it also has macroblocks and blocks containing interpolation parameters and DCT coded correction values. The most compression is obtained by using as many B pictures as possible. However, to perform B decoding, the "future" I or P picture involved must be transmitted before any of the dependent B pictures can be processed. This inherently means that there is a delay in the decoding proportional to the number of B pictures in series.

(i) Pixel : A pixel is made of a triad. Pixels are arranged in an array of rows. Each row forms a scan line.

(ii) Roping display terminology : Roping causes straight lines to appear twisted or helical. This is caused by poor convergence as successive pixels in the line show different edge colors.

6. (e)

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