Lecture 8: Video Intro to IT COSC1078 Introduction to Information Technology Lecture 8 Video James Harland

Lecture 8: VideoIntro to IT Introduction to IT 1 Introduction 2 Images 3 Audio 4 Video 5 Binary Representation WebTest 1, Assignment 1 6 Data Storage 7 Machine Processing 8 Operating Systems WebLearn Test 1 9 Processes Assignment 2 10 Internet 11 Internet Security WebLearn Test 3 12 Future of ITAssignment 3, Peer and Self Assessment

Lecture 8: VideoIntro to IT Overview  Questions?  WebLearn Test 1  Assignment 1  Video  Questions?

Lecture 8: VideoIntro to IT Web Test 1  Week 5  Quizzes (practice tests) up now  Content will be on weeks 2-4 Images Audio Video

Lecture 8: VideoIntro to IT Introduction Who is this bloke?

Lecture 8: VideoIntro to IT Overview …

Lecture 8: VideoIntro to IT Images and Perspective … Frame rate is often 30 per second COOL! BORING!

Lecture 8: VideoIntro to IT Time codes and all that … Time for videos HH:MM:SS:FF HH hours MM minutes SS seconds FF frames Often 30 frames per second (nice and neat!) NTSC colour uses frames per second (!!) This means there are two timecode systems ….

Lecture 8: VideoIntro to IT Non-drop-frame timecode HH:MM:SS:FF Behaves as expected FramesMinutes (30 fps) Non-drop-frame timecode :00:59: :01:00: :09:59: :09:59: :10:00:00

Lecture 8: VideoIntro to IT Drop-frame timecode HH;MM;SS;FF Seems bizarre! Skips time codes 00;01;00;00 00;01;00;01 00;02;00;00 00;02;00;01 00;03;00;00 00;03;00;01 …. 00;09;00;00 00;09;00;01 Skips 18 codes per 10 minutes 00;00;59;29 00;01;00;02 … 00;01;59;29 00;02;00;02 … 00;09;59;29 00;10;00;00

Lecture 8: VideoIntro to IT Drop-frame timecode FramesMinutes (29.97fps) Minutes (30 fps) Drop-frame timecode Non-drop- frame timecode ;00;59;2900:00:59: ;01;00;0200:01:00: :09:59:2900:09:59: ;10;00;0000:09:59: ;10;00;1800:10:00:00

Lecture 8: VideoIntro to IT Video file size Video files can be big! How much space is need for 1 second of HDTV? 1440 x 1080 pixels 24-bit colour 30 fps Stereo (2 audio channels) Audio sampling 48 kHz and 16-bit depth

Lecture 8: VideoIntro 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 KB Video: 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: VideoIntro 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 pixels NameYUVSizeSaving 4:4:44Y, 4U, 4V120% 4:2:24Y, 2U, 2V833% 4:2:04Y, 2 (U or V)650% YUV YYYY YYYY UV UU

Lecture 8: VideoIntro 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: VideoIntro 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: VideoIntro 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: VideoIntro to IT Conclusion  Get Assignment and WebTest done this week, if possible  Submit early!  Keep reading! (book particularly)