Video

1. Video • Digital Video is composed of a series of bitmap graphics, each one called a frame • Powerful communication media: video with sound more convincing than a scrolling text filed with the same speech. • Before you decide to add video to your project it is important to have understanding of the medium, its limitation and cost. • The cost of video Filming costs Processing / editing costs Data budget costs Cognitive costs

2. Digital or analogue • Professional digital equipment is no longer expensive. • Digital filming is becoming common for low budget and multimedia projects. • Digital camcorder directly connected to computer brings the power of video editing to every day users.

3. The Video Process • When light reflected from an object passes through a video camera, that light is converted to an electronic signal by one or more Charge Coupled Devices (CCD). • CCD output is processed, by camera, into RGB signals, and combined with a synchronization pulse. • Types of video signal – RGB preferred: three separate signals, one for each of R, G, & B. – Component Video: two separate signals one for chroma (color information) and one for brightness. – Composite Video - single signal containing all information.

4. Analogue Video • Video signal (RGB, Component or Composite) is written to magnetic tape. • Audio track at top of tape (one or two channels). • Video track in the middle of the tape. • Control track at bottom of tape - contains synchronization pulses.

5. Broadcast Standards • NTSC • PAL • SECAM • HDTV

6. NTSC Standard • National Television Standards Committee (1952) • US & Far East • A single frame of video is made up of 525 scan lines • 30 frames per second (each frame takes 1/30 of a second • Interlaced: lines are drawn in two passes (odd/even) each at rate of 60Hz

7. PAL Standard • Phase Alternate Line (PAL) is an integrated method of adding color to B&W television signal. • UK, most of Europe, Australia & South Africa • 625 scan lines • 25 frames per second • Interlaced at 50Hz

8. SECAM Standard • Sequential Color and Memory • France & Russia • 625 scan lines (as PAL) • 25 frames per second (as PAL) • Interlaced at 50Hz (as PAL) • Color model completely different from PAL

9. HDTV (High Definition Television) • Six separate HDTV “standards” in two categories: • 1920x1080 at (24, 30, and 60 fps). Interlaced & most favored by broadcasting industry • 1280x720 progressive-scan at 24, 30, and 60 fps

10. Conversion between analogue formats • PAL / SECAM conversion is fairly easy (i.e. cheap) • PAL & SECAM / NTSC conversion is much more complex (i.e. expensive) • Low quality conversion is now cheap & dual standard equipment exists • High quality conversion remains expensive

11. Why HDTV? • Higher-resolution picture • Wider picture • Digital surround sound. • Additional data • Easy to interface with computers

12. Video Color Models • Computers use RGB component video and their colors are purer and more accurate than those seen on TV. • NTSC, PAL & SECAM use different colors models and limited palette. Thus graphic images created on computers may display differently when transformed into any of the TV systems. • Not all RGB colors are available on conventional TV sets. • So if the MM project is to be delivered to playstation, it may not play back. In this case use colors to meet NTSC color.

13. Digital Video Source • Film as digital video using FireWire standard cable. • Film as analogue and then digitized it. To accomplish that a video capturing board is needed. – Wildly variable in price and quality

14. What kinds of Digital Videos? • Classified by its platform or application (how it will be delivered) • Desktop video (DTV) • Videos constructed and displayed using a personal computer • Web-based video • Incorporated in Web pages and accessed with a browser • DVD-video • A DVD format used for commercial DVDs that contain feature-length films. • PDA video • Small-format video designed to be viewed on a PDA or cell phone screen

15. Digital Video Playback • Playback Software • Microsoft Video for Windows – Framework for video playback – Audio Video Interleave (AVI) • Apple Quicktime – Framework for all time-based media – Movie files (MOV) – Bundled with MacOS – Quicktime for Windows

16. Video Compression I • Video compression is always lossy. • Multi-way trade-off – File size / transfer rate (bandwidth) – Frame rate (typically 15fps for multimedia) – Image quality – Frame size • Different codecs have differing strengths and weaknesses.

17. Video Compression II • discards “repetitive” or “redundant” data; may not be noticeable to the eye • results in a compression ratio as large as 200:1 in some cases • Greater ratio, poorer the decompressed image • applied to video because quality loss not noticeable in moving images • Applied to Internet streaming • Applied to .jpg and .mpeg formats

18. Spatial Compression vs. Temporal Compression • Spatial • Compress each frame individually • Uses the same techniques as JPG compression • Codecs that do spatial compression are: Animation, PlanarRGB • Temporal • Just save info on selected frames (called keyframes) • All other frames just save the differences from the previous keyframe • Good when the difference between current frame and keyframe is small

19. Compression Codecs • Framework (V4W or Quicktime) does not contain compression software. • Compression software using a specific algorithm is called a codec (coder/decoder). • Examples of Codecs: • Indeo • MPEG

20. Indeo • Algorithms developed for DVI - Intel i750 chipset • Indeo - implemented in software • Two levels of compression – PLV (Production Level Video) – RTV (Real Time Video) • Typical compression ratio of 160:1

21. MPEG • Moving Picture Expert Group • Established by ISO in 1988 • Defined standards are used in – Digital television – Video phones – Consumer electronics – Digital cinema – Video games

22. MPEG1 • The original MPEG standard • Objective - deliver video and audio from CD-ROM with comparable quality to VHS tape and CD audio. • Encodes an audiovisual signal in about 1.5 Mbps • Images are progressively scanned • Standard is in five parts – 1. Systems – 2. Video – 3. Audio – 4. Conformance testing – 5. C implementation (encoding and decoding)

23. Applications of MPEG 1 • Consumer Devices • Multimedia / CD ROM • Internet Video. • Compression is cheap • Video CD - production is extremely cheap • Audio only devices (MP3 players) • Internet audio

24. MPEG 2 • Dates from 1990, a completely different standard from MPEG 1. • Objective - deliver video and audio at comparable quality to broadcast composite video at roughly 4 times the typical MPEG 1 bit rate. • Improvements over MPEG 1 – Higher resolution – Higher image quality – Supports interlaced video formats – Multiresolution scalability – Multiple sound track features • Encryption and metadata capabilities

25. Applications of MPEG 2 • Digital Satellite TV • Digital Cable TV • DVD • Some multimedia (usually where very high quality is essential)

26. MPEG 4 • MPEG 4 is capable of encoding digital video objects of any shape • Thus the screen can consist of many different video objects. • For example different “people” can stay together around a table • 2D images can be represented in 3D space.

27. MPEG 4 • MPEG 4 has the following capabilities: • Encode natural or synthetic images. • Real-time or non real-time. • Streams from different sources can be combined • Contains the possibility of interaction with objects. • Hyperlinking, and uploading and downloading of data • Readily adjusts delivery to available bandwidth • Microsoft and Apple are implementing it in their core technologies (ie Windows media services and Quicktime)

28. MPEG-7 • Multimedia content description interface • Aimed at addressing issues of content retrieval • Intended primarily for digital libraries • Object based (as MPEG-4) • Supported data: • Still images • 3D models • Sampled audio • Speech • Video • Composition information (combinations of the above) • Data representation • Binary objects, XML or both

29. MPEG-21 • Designed to manage digital media resources • Digital item declaration • Digital item identification and description • Content management and usage • Intellectual property management and protection • Terminals and networks • Content representation • Event reporting

30. Creating Digital Video 30

31. Ready to Make a Video I • Pre-Production Stage: • Planning the video and gathering any resources you might need • Length of final video • Music or sounds, script or storyboard  http://www.youtube.com/watch?v=t3mAHQuBqQI • Camcorder type and medium and format of final video 31

32. Ready to Make a Video II • Production Stage: • Camera work and sound recording • The potential for a good shot is better if you understand how to use the technical controls on your camera, i.e. resolution, capturing action shots vs. stills, night time vs. daytime shots. All of these shots require certain settings on your camera to get the best quality. 32

33. Ready to Make a Video III • Post-Production: • Downloading from camcorder to computer • Editing and/or encoding the finished video. • Removing unwanted footage • Arranging desired footage in the correct order • Adding music, titles, transitions and possibly other effects • Converting (encoding) into the correct format(s) 33

34. Ready to Make a Video IV Assumption that you have caught your video on a camcorder Post-Production Stage Capture Video • Download video from camcorder to computer Edit Digital Video (using Computer, Digital Video softwareex. Adobe Premiere, Avid) • Edit it • Add all kinds of cool titles • Filters, transitions • Superimpose clips • Synchronize audio with video • Authoring software: create menus and interactivity Output Video • Output to different file formats • Back out to tape, the Web, CD, DVD 34

35. Ready to Make a Video – Post Production Let’s take a closer look! Edit Digital Video (using Computer, Digital Video softwareex. Adobe Premiere, Avid) • Edit it • Add all kinds of cool titles • Filters, transitions • Superimpose clips • Synchronize audio with video • Authoring software: create menus and interactivity Capture Video • Download video from camcorder to computer Output Video • Output to different file formats • Back out to tape, the Web, CD, DVD 35

36. Capturing Video –Download video from camcorder to computer To use video in a multimedia application, it must be in digital form So how do you get a camcorder video into digitized form? Video card _____________ ____________ 36

37. Capturing Video Five factorsto consider when making a video (4) Computer: Download video to edit Source Device:Camcordersand digital video cameras can be used to capture full-motion images.(Analog versus Digital) (3) Connecting method (2) Video Capture Device • Video Capture Card needed (if using analog camcorder from analog to digital) • No need if source device outputs a digital signal (such as Firewire or USB) (5) Software: Capturing, Editing, Outputting 37

38. Capturing Video –Video Capture Device Analog Camcorder:Need Video capturing card Digital Camcorder : Firewire connection Analog Digital Video • S video (better quality) • Yellow RCA Audio Firewire 38

39. Firewire vs. USB  The Back Story • Firewire 400 created by Apple • Apple wanted to charge 1 dollar for every machine that was going to use it, this caused most PC manufacturers to decide against it, in favour of USB 1.1. • Transmitted originally at 400Mbps • Peer to Peer Technology (can daisy chain one camcorder to another WITHOUT a computer) • USB 1.1. could transmit at 12Mbps • Used for mice, keyboards, printers, too slow for video • USB 2.0 came along, backward compatible, transmitted at 480Mbps (could beat with Firewire400 and do video) • Master/Slave technology (need to connect to a computer) • Currently, we have Firewire 800, transmits at 800 Mbps, at some point in the future, they expect new Firewire will transmit at 3.2 Gbps! 39

40. Controlling the Transfer Process • Video Capture software should have the following features: • Start and stop the transfer • Select a file format for storing your video footage • Specify file name for each video clip • Video capture software is supplied with video editing software and with video capture devices TIP: Videos are easier to edit if you divide them into several files, each containing a one or two minute video clip. 40

41. Editing Digital Video Capture Video (using video capture card) from camcorder to computer Edit Digital Video (using Computer, Digital Video softwareex. Adobe Premiere, Avid) • Edit it • Add all kinds of cool titles • Filters, transitions and FX • Superimpose clips • Synchronize audio with video • Output in different file formats Output Video (back out to tape, the Web, CD, DVD) 41

42. Video Editing Software I • Arrangevideo clips on time line • Add all kinds of cool titles • Filters, transitions • Superimpose clips • Synchronize audio with video Output in different file formats

43. Video Editing Software II

44. Output Video Capture Video (using video capture card ) from camcorder to computer Edit Digital Video (using Computer, Digital Video softwareex. Adobe Premiere, Avid) • Edit it • Add all kinds of cool titles • Filters, transitions and FX • Superimpose clips • Synchronize audio with video • Output in different file formats Output Video (back out to tape, the Web, CD, DVD) Challenge: Efficient Delivery via Web

45. Output Video • Why do we need codecs? • Speed up downloads --- 10 times smaller than uncompressed video files. • Without codecs, downloads would take 3-5x longer than they do now • There are different codecs • codecs for audio and video compression, for streaming media over the Internet, videoconferencing, playing mp3's, speech, or screen capture • The codec used to compress is the one needed to view • Two widely used media players: • Apple’s QuickTime (QuickTime for Windows) • MS Windows Media Player (uses AVI or WMV format ) • Most media players including these will play videos produced with a variety of codecs

46. Which file type? Answer the following 3 questions: • Is the video for the web, or for DVD, or if it is an older CD Rom, how fast is the playback? • Who is my audience? • Will they have a Mac or a Windows machine? Perhaps both, then you need a cross platform format. • How will they watch it, on a computer, how old is the computer, on a DVD player? • Will I be editing the video again later on? Maybe I don’t want to lose any data?

47. Video Files

48. Exploring Video for the Web Challenge: Transfer rate File Size File Type Challenge: Format

49. Video Transfer for the Web 2 types of Video Transfer RTSP Real-Time Streaming Protocol HTTP Hypertext Transfer Protocol • Played directly from the server tothe user’s computer in a process called “streaming”. • RTSP allows the user to perform tasks such as pause and play Download the Video from the host (server)to the user’s computer in its digital form

50. Video Transfer for the Web HTTP RTSP • Downloads the entire video to user computer • User must wait for the download processto end • Video can be played repeatedly and copied if necessary • Process called streaming • File played directly from server – thus some delay • Video is broadcast to user and after displayed, discarded