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

Who is this bloke?

Lecture 8: Video Intro to IT

Overview Questions?

WebLearn Test 1

Video

Questions?

Lecture 8: Audio Intro to IT

Introduction to IT1 Introduction 2 Images3 Audio4 Video WebLearnTest 1 5 Binary Representation Assignment 16 Data Storage7 Machine Processing8 Operating Systems WebLearn Test 19 Processes Assignment 210 Internet11 Internet Security   WebLearn Test 312 Future of IT Assignment 3, Peer and Self Assessment

Lecture 8: Video SE Fundamentals

Questions?

How did you spend 6-8 hours on this course last week? This week?

Lecture 8: Video Intro to IT

Assessment Process Submit all assignments via Blackboard in the

Learning Hub Assignment 1 due 11.59pm Sunday 1st April Assignment 2 due 11.59pm Sunday 6th May Assignment 3 due 11.59pm Sunday 27th May Late assignments attract a penalty of 10% per

day late, up to a maximum of 50%

Lecture 8: Video Intro to IT

Assignment Assignment will be in three parts Overall task is to produce a video Groups of up to 3 Assessed by final video and group blog Part 1: images and audio (end of week 5) Part2: hardware (end of week 9) Part 3: reflection, research (end of week 12)

Lecture 8: Video Intro to IT

Assignment 1

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

Use Audacity to perform some manipulations on sound

Use a movie making tool to produce something like (and much better than!) ‘Lord of the Controllers 1 & 2’

Email me your group and its name so that I can set up a blog on the Learning Hub

Lecture 8: Video Intro to IT

Overview 01010100001010101010100110100010101001101001010010100011100010101010100101111001001010…

Lecture 8: Video Intro to IT

Images and Perspective …Frame rate is often 30 per second

COOL!

BORING!

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 00:00:59:291800 1 00:01:00:0017981 9.989 00:09:59:1117982 9.990 00:09:59:1218000 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 00:00:59:291800 1.001 1 00;01;00;02 00:01:00:0017981 9.999 9.989 00:09:59:29 00:09:59:1117982 10 9.990 00;10;00;00 00:09:59:1218000 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 SamplingEye 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 rateOverall 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

Conclusion

Get Assignment and WebTest done this week, if possible

Submit early!

Keep reading! (book particularly)