Lecture 8: Video Intro to IT

COSC1078 Introduction to Information Technology

Lecture 8

VideoJames Harland

james.harland@rmit.edu.au

Lecture 8: Video Intro to IT

Introduction to IT

1-3 Introduction, Images, Audio

4 Video

5 Computer Fundamentals Assignment 1, WebLearn Test 1

Tuesday March 30th, Wednesday March 31st

(no classes Thursday 1st April, Tuesday 6th April, Wednesday 7th April)

6 Computer Fundamentals

Tuesday April 13th, Wednesday April 14th

7 Computer Fundamentals

8 Operating Systems WebLearn Test 1

9 Operating Systems Assignment 2

10 Internet

11 Internet Security   WebLearn Test 3

12 Future of IT Assignment 3, Peer and Self Assessment

Lecture 8: Video Intro to IT

Overview

Questions?

WebLearn Test 1

Assignment 1

Video

Questions?

Lecture 8: Video Intro to IT

Web Test 1

Now Week 5, not week 4 (so not this week)

Quizzes (practice tests) up later this week

Content will be on weeks 2-4

Images

Audio

Video

Lecture 8: Video Intro to IT

Assignment 1

Due date is 9.00am on Monday 12th April (1st day of Week 6)

Forget whatever this bloke said yesterday

Can submit now if you wish …

Sensible to submit something soon

Lecture 8: Video Intro to IT

Introduction

Who is this bloke?

Lecture 8: Video Intro to IT

Overview

01010100001010101010100110100010101001101001010010100011100010101010100101111001001010…

Lecture 8: Video Intro to IT

Time codes and all that …

Time for videos HH:MM:SS:FFHH hoursMM minutesSS secondsFF frames

Often 30 frames per second (nice and neat!)NTSC colour uses 29.97 frames per second (!!)

This means there are two timecode systems ….

Lecture 8: Video Intro to IT

Non-drop-frame timecode

HH:MM:SS:FF Behaves as expectedFrames

Minutes (30 fps)

Non-drop-frame timecode

1799 0.9994 00:00:59:29

1800 1 00:01:00:00

17981 9.989 00:09:59:11

17982 9.990 00:09:59:12

18000 10 00:10:00:00

Lecture 8: Video Intro to IT

Drop-frame timecode

HH;MM;SS;FF Seems bizarre!Skips time codes 00;01;00;00 00;01;00;0100;02;00;00 00;02;00;0100;03;00;00 00;03;00;01…. 00;09;00;00 00;09;00;01 Skips 18 codes per 10 minutes

00;00;59;2900;01;00;02…00;01;59;2900;02;00;02…00;09;59;2900;10;00;00

Lecture 8: Video Intro to IT

Drop-frame timecode

Frames

Minutes (29.97fps)

Minutes (30 fps)

Drop-frame timecode

Non-drop-frame timecode

1799 1.0004 0.9994 00;00;59;29 00:00:59:29

1800 1.001 1 00;01;00;02 00:01:00:00

17981 9.999 9.989 00:09:59:29 00:09:59:11

17982 10 9.990 00;10;00;00 00:09:59:12

18000 10.010 10 00;10;00;18 00:10:00:00

Lecture 8: Video Intro to IT

Video file size

Video files can be big!

How much space is need for 1 second of HDTV?

1440 x 1080 pixels24-bit colour30 fpsStereo (2 audio channels)Audio sampling 48 kHz and 16-bit depth

Lecture 8: Video Intro to IT

Video file size

Audio: 48,000 samples/s x 1s x 16 bits/sample x 2 = 1,536,000 bits = 192,000 byes ≈ 188 KBVideo: 1440 x 1080 pixels/frame x 24 bits/pixel = 37,324,800 bits/frame 37,324,800 bits/frame x 30 fps x 1s

= 1,119,744,000 bits = 139,968,000 bytes = 133 MB (!!)

This takes 133MB per second! Need to compress

Lecture 8: Video Intro to IT

Colour Sampling

Eye more sensitive to brightness than colour

YUV model: Y luminance U,V chrominance

3 samples per pixel, so 12 samples per 4 pixelsName

YUV Size Saving

4:4:4 4Y, 4U, 4V 12 0%

4:2:2 4Y, 2U, 2V 8 33%

4:2:0 4Y, 2 (U or V) 6 50%

YUVYUVYUV YUV

YYY Y

YYY Y

UVUV

U U

Lecture 8: Video Intro to IT

File size and Data rate

Overall file size is one thing

133MB x 60 minutes/second x 60 minutes/hour x x 2 hours = 957,600 MB ≈ 935 GB (!!)

Still need to be able to extract data at 133MB per second, even for only 1 second …

48x CD is about 7MB per second ..

Lecture 8: Video Intro to IT

Compressing Video Files

Lower frame size Lower frame rate Lower picture quality (ie data rate) Lower colour depth (not often done …) Lower audio quality (not much effect) Compression methods (lossy vs lossless)

compressor/decompressor or codec

Lecture 8: Video Intro to IT

Assignment 1

Use GIMP (or a similar tool) to perform some manipulations on an image

Address two issues in relation to this

Lab classes 2 and 3 based around GIMP

Main emphasis is on process, not result!

Is in the Learning Hub

SUBMIT VIA WEBLEARN

JUST DO IT!

Lecture 8: Video Intro to IT

Assignment 1

Lecture 8: Video Intro to IT

Conclusion

Web Test next week (week 5)

Do online quizzes later this week

Keep reading! (book particularly)

Notes for Video in Learning Hub