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BITS PilaniPilani Campus

BITS Pilani presentation

Dr. Mukesh Kumar RohilWILP Division

BITS PilaniPilani Campus

Online Lecture 09 (As Tutorial One) EA ZC473 (Multimedia Computing)

BITS Pilani, Pilani Campus

Multimedia Computing (EA ZC473): On-line Tutorial One

On-line Tutorial One

Dr. Mukesh Kumar RohilChief-Instructor of the course on Multimedia

Computing

Work Integrated Learning Programmes Division

Birla Institute of Technology & Science

Pilani – 333031 (Rajasthan)


Learning Objectives

Some problems from the syllabus of first eight weeks of study plan


Q1.

• Why do we need to study the media Graphics, Images, Audio, Animation and Video at the basic level in the diagram given in the next slide?


The Main Fields of Multimedia Systems : Global Structure


Q2 What are various uses of MM Systems?1. Video teleconferencing.2. Distributed lectures for higher education.3. Tele-medicine.4. Co-operative work environments.5. Searching in (very) large video and image

databases for target visual objects.6. Augmented" reality: placing real-appearing

computer graphics and video objects into scenes.


Uses of Multimedia Systems … 2

7. Including audio cues for where video-conference participants are located.

8. Building searchable features into new video, and enabling very high- to very low-bit-rate use of new, scalable multi-media products.

9. Making multimedia components editable.

10.Building \inverse-Hollywood" applications that can re-create the process by which a video was made.

11.Using voice-recognition to build an interactive environment, say a kitchen-wall web browser.


Q3. How animation is different from captured video?


Q4. How we recognize a person only by hearing his/her voice?

• Tones and Over tonew• Phase differences


Q5. Why variety of digitization formats are used for video?


Q6. How concepts of TV are related to Video media of a Multimedia System?


Q7 Usually errors in audio are less tolerable than errors in video. Why?


Q8. Are text and Graphics related? If yes show by one example?


Q9. How formatted text is different from Hypertext?


Q10. Why human eye is less sensitive to detect small changes in color as compared to intensity?


Q11. For what different purposes we do use Color Lookup table?


Q12. What are the two differences between Graphics and Image media?


Q13. How to use LDU in hierarchical form?


Q14. What will be the storage space required for a binary image of an A4 size pages if 200 dots per inch are recorded? What will be the size for 24-bit color image?


Q15. What is in-betweening?


Q16. Which media stereo-Audio or color Video at 480 x 320 at minimum refresh rate requires more storage space per unit time?


Q17. Name some transformations which can be applied on an image?


Q18. Can text and audio be related in a Multimedia System? If yes how?


Q19. What is quantization error? How it can be reduced?


Q20. Name some media types other than text, graphics, image, audio, animation and video.


Q21. Why video without associated audio is less preferred? Even though we accept Audio alone as a media?


Q22. What is rendering in context of animation?


Q23. What is the significance of I frame?


Q23. What are the advantages of arithmetic coding?


Q24. Why a DVD can store more data than a CD?


Q25. What is 4:4:4 digitization format?


Q26. Why do we not just use JPEG 2000 to compress each frame of video?


Some questions from old EC1 Regular Q1.1 • How presentation medium is different from

representation medium?

Ans.

Presentation refers to tools and devices for input and output of information. (Screen, Paper, Speaker etc.)

Representation means internal computer representation of information. (File Formats)


Some questions from old EC1 Regular Q1.2 • How formatted text is different from

hypertext in the terms of their organization in multimedia systems?

• Ans.

• Formatted Text: Control Characters for formatting-specific information.

• Hypertext: Graph structure


Some questions from old EC1 Regular Q1.3

• List difference between Isochronous and Synchronous mode of transmissions.

• Isochronous: Min and Max time delay. For streaming (time-dependent media).

• Synchronous: Max time delay. For Other media.


Some questions from old EC1 Regular Q1.4 • Using an example, explain how LDU can

be used for hierarchical representation of a media.

• Ans.

• Pixels form a macroblock, macroblocks results in frames, a sequence of frames makes a clip and finally a number of video clips makes a movie.


Some questions from old EC1 Regular Q1.5 • Specify range of frequencies for which

human are more sensitive as compared to other frequencies in the audible range?

• Ans. 1 kHz to 7 kHz


Some questions from old EC1 Regular Q2.1 • Given a signal comprises of two acoustic

waves 110cos(200*pi*t) and 110cos(220*pi*t). Calculate value of frequency of alias signal if the signal is sampled at 210 Hz.

Ans.

105 Hz


Some questions from old EC1 Regular Q2.2 • A true color (24-bit representation) video, with

refresh rate of 50 Hz and with resolution 640 x 480, of 15 minutes duration is to be transmitted in 5 seconds. Find the required rate (in Mbits/sec) for the transmission in uncompressed form.

• Ans.

Size of video = 24*(50*15*60)*640*480 bits

= 316406.25 Mbits (1 M = 10242)

Rate = 316406.25/5 = 63281.25 Mbits/sec



• Which two audio signals among the co-existing signals 20cos(10000*pi*t), 20cos(10000*pi*t + pi/2), 30sin(pi/2 - 10000*pi*t), 100sin(30*pi*t), and 100cos(30*pi*t) can be distinguished by a human being when heard?

• Ans. Due to frequency masking only signals 30sin(pi/2 - 10000*pi*t) and 100sin(30*pi*t) will be heard.


Some questions from old EC1 Regular Q2.4 • Calculate entropy of the data given in the

Table 1.

• Ans. 2.92

Character a e h g b d c f

Frequency 1400 800 500 500 1100 900 1000 700



• An analog signal has a dynamic range of 81 dB. Determine expression for the minimum number of bits to be used to have quantization noise not more than 1.25% of the minimum amplitude. Also find minimum amplitude in terms of maximum amplitude.


Ans. … EC1 Regular Q2.5

81 = 20log10(Vmax/Vmin)

For b bits, q = 2Vmax/2b,

e = q/2 = (1.25/100)*Vmin

Now, find Vmin in terms of Vmax and find b in terms of Vmax


Some questions from old EC1 Regular Q3• Given the frequency table as in Table 1,

decompress 0.125 using arithmetic decompression method. Find the ranges in order of a to h in sequence. Perform only first six iterations.

Character a e h g b d c f

Frequency 1400 800 500 500 1100 900 1000 700


Ans. …EC1 Regular Q3

• 0.125 / a / 0.203 / 0 / 0.203

• 0.616 / b / 0.159 / 0.464 / 0.623

• 0.955 / f / 0.101 / 0.899 / 1

• 0.560 / b / 0.159 / 0.464 / 0.623

• 0.603 / b / 0.159 / 0.464 / 0.623

• 0.875 / c / 0.145 / 0.754 / 0.89


Some questions from old EC1 Regular Q4

• Apply LZW and indicate the output and entries in the string table, to encode the following string: ababbaabbaaabb

• Assume the string table initially contains codes from 0 to 127, with the codes 91 and 92 allocated to characters a and b. Assuming that originally a character is stored in 7-bit, find compression ratio achieved by compressing the above string using LZW.


Ans. ….EC1 Regular Q4

• Apply LZW to get

• StringTable = [ab,ba,abb,baa,abba,aa,aab,bb] starting at 128

• Output = [a,b,ab,ba,abb,a,aa,b,b] the codewords for these i.e. 91, 92, 128, 129. etc.


Some questions from old EC1 Regular Q5

• Find Huffman code-words (optimised for minimum possible length) and the achieved compression ratio using Huffman coding, for the data given in Table 1. Assume originally a character is stored using 8-bit.

Character a e h g B D c f

Frequency 1400 800 500 500 1100 900 1000 700


Ans. EC1 Regular Q5

Char Freq Code

A 1400 10

B 1100 11

C 1000 010

D 900 011

E 800 0000

F 700 0001

G 500 0010

H 500 0010

Huffman Tree• 6900• / \ • 4400 2500 • / \ a b• 2500 1900• / \ / \• 1500 1000 c d • e f g h


Ans. EC1 Regular Q5 …

• C.R. = (6900*8) / (500*4 + 500*4 + 700*4 + 800*4 + 900*3 + 1000*3 + 1100*2 + 1400*2)

• = 2.667


EC1 Regular Q6

Explain working of a CD/RW disk based on Magneto-Optical technology.


Ans. EC1 Regular Q6

• Disk recording layer is magnetically recordable

• Uses weak magnetic field to record data under high temperature (150o C, Curie temperature)

• Coercivity at curies temperature becomes zero

• Two passes in writing:– 1. Erase (set polarity to 0)– 2. Write (set polarity to 0 or 1 depending on data)


End of Outline of solution to Some questions from old EC1 Regular


Thanks ….

Any questions please …..

You can mail to course-list or at [email protected]

Thanking you all

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