Elements of Multimedia Video - CSC441

ELEMENT OF MULTIMEDIA VIDEO Compiled by: Ts. Dr. Rashidah Mokhtar OUTLINE Digitized Video Streamed Video Video Standard 5 Introduction to Video Compression, Quick Time Editing & Post-Production DIGITIZED VIDEO 6 193–195 DIGITIZATION • In the camera – DV + Firewire • In the computer...

ELEMENT OF MULTIMEDIA VIDEO Compiled by: Ts. Dr. Rashidah Mokhtar OUTLINE Digitized Video Streamed Video Video Standard 5 Introduction to Video Compression, Quick Time Editing & Post-Production DIGITIZED VIDEO 6 193–195 DIGITIZATION • In the camera – DV + Firewire • In the computer – video capture card • Digitization in camera (DV) means less noise • Less noise allows better compression 200 INTERLACING • a technique of improving the picture quality of a video signal without consuming extra bandwidth. Interlaced video was designed for display on CRT televisions. • Required for TV, so encountered in captured footage • In television, the electron beam makes two passes on the screen while drawing a single video frame. • It first lays down all the odd-numbered lines, and then all the even-numbered lines, hence they are interlaced. • While capturing images from a video signal, they can be filtered through a de-interlacing filter provided by image-editing applications. • Each frame is divided into two fields • Field 1: odd lines; Field 2: even lines • Fields are transmitted one after the other • Frame is built out of the interlaced fields OVERSCAN AND THE SAFE TITLE AREA • Analog television sets remain the most widely installed platforms for delivering and viewing video. • Overscan occurs when an image is larger than the standard TV screen. • Underscan occurs when computer monitors display a smaller image on picture tube. • The safe title area is where the image will not be affected by overscanning, even in the worst conditions. DIGITAL VIDEO BROADCAST High Definition Television (HDTV) This digital standard provides TV stations with sufficient bandwidth to present four or five Standard Television (STV) signals or one High Definition TV (HDTV) signal. This standard allows for transmission of data to computers and for new Advanced TV (ATV) interactive services. Digital video broadcast Advanced Television System Committee (ATSC) These standards provide for digital STV and HDTV recordings that can be broadcast by digital TV transmitters to digital TV receivers. ATSC standards also provide for enhanced TV bringing the interactivity of multimedia and the Web to broadcast television. DIGITAL VIDEO Advantages Disadvantages Easy to edit sequences of video (frame by frame) high capacity storage Easy to add special effects Easily duplicated (piracy) Quality of the original video are Require high-end pc to process and retained / maintained in the new copy. deliver (fast processor, plenty of RAM, Digital mastering means that quality will fast and big hard disk never be an issue Better image and audio quality (digital quality). Digital video reduces generational losses suffered by analog video Long lasting, offer superior quality at a given cost User need to have good knowledge and background in video compression and technology STREAMED VIDEO 12 197 STREAMED VIDEO • Play back a video stream as it arrives over a network (like broadcast TV), instead of downloading an entire video clip and playing it from disk (like renting a DVD) • HTTP Streaming • Start playing a downloaded clip as soon as enough of it has arrived • Starts when the (estimated) time to download the rest is equal to the duration of the clip VIDEO STANDARD 14 199 VIDEO STANDARDS • Digital video devices must conform to standards • Digital standards must maintain compatibility with older analogue standards for broadcast TV • Western Europe, Australia & New Zealand, China,… • Frame has 625 lines, 576 are picture • 25 frames (50 fields) per second PAL (Phase Alternating Line) • North America, Japan, Taiwan, parts of South America,… • These standards define a method for encoding information into electronic signal that creates a television picture. • Frame has 525 lines, 480 are picture • 29.97 frames (59.94 fields) per second • (Often quoted as 30 frames per second) • France and former Soviet Union • Standard only used for transmission • Uses PAL cameras etc • SECAM has a screen resolution of 625 horizontal lines and is a 50 Hz system. • SECAM differs from NTSC and PAL color systems in its basic technology and broadcast method. NTSC (National Television Standards Committee) SECAM (Séquential Couleur avec Mémoire) NTSC: NORTH AMERICAN BROADCAST TELEVISION STANDARD; INITIALS STAND FOR NATIONAL TELEVISION STANDARDS COMMITTEE. PAL: BRITISH BROADCAST TELEVISION STANDARD; INITIALS STAND FOR PHASE ALTERNATING LINE. SECAM: FRENCH AND ASIAN BROADCAST TELEVISION STANDARD; INITIALS STAND FOR SYSTÈME ELECTRONIQUE COULEUR AVEC MÉMOIRE, WHICH TRANSLATES AS ELECTRONIC COLOR SYSTEM WITH MEMORY. INTRODUCTION TO VIDEO 17 INTRO TO VIDEO • The term "video" commonly refers to related types of carrier formats —which can either be digital (DVD, Quicktime, Ogg) or analog videotape (VHS, Betamax). • Television broadcasting and home movies have long been the traditional application of video technology. • We used to live in a world of analog images and video, where we dealt with photographic film, analog TV sets, video cassette recorders (VCRs), and camcorders • The Internet has made possible the rise of compressed video file formats to syndicate video files to a global audience. • Video is also used in scientific engineering, manufacturing, and security applications. USING VIDEO • Video is an excellent tool for delivering multimedia. • Video places the highest performance demand on computer and its memory and storage. • Digital video has replaced analog as the method of choice for making and delivering video for multimedia. • Digital video device produces excellent finished products at a fraction of the cost of analog. • Digital video eliminates the image-degrading analog-to-digital conversion. • Many digital video sources exist, but getting the rights can be difficult, time-consuming, and expensive. EXAMPLE OF VIDEO IN MULTIMEDIA PROJECT Splice: Creating Recycle Robots - edited by teacher Creating Keith Haring Art Projects - filmed and edited by 4th and 5th graders iMovie: Proper Care and Feeding of iPads Southfield Christian teachers create their first movie using their new iPads! Physics Lab - Are you taller standing or lying down? - from Gary Faust's physics class iTimelapse: Watercolor Painting Timelapse Video iStopMotion Apple Still Life - capture of students at work in art class Animoto: Grace's Animoto - student photographs classmates at work and makes Animoto video Cartoonatic: Strip Structures - filmed with Cartoonatic, edited in Splice, uploaded to internet using Vimeo Silent Movie Director: Computer Lab Rules - teacher filmed first graders and edited to created these silent movies HOW VIDEO WORKS Video basics • Light passes through the camera lens and is converted to an electronic signal by a Charge Coupled Device (CCD) • Most consumer-grade cameras have a single CCD. • Professional–grade cameras have three CCDs, one for each Red, Green and Blue color information (RGB) • The output of the CCD is processed by the camera into a signal containing three channels of color information and synchronization pulse (sync). COMPRESSION, QUICK TIME 22 DIGITAL VIDEO COMPRESSION • Because of the large sizes associated with video files, video compression/decompression programs (Codec) have been developed. • Digital video compression schemes or codecs is the algorithm used to compress (code) a video for delivery. • Lossless compression à preserve image throughout the compress/decompress process. • Lossy compression à eliminates some of the data in the image (greater compression ratios) à usually used for video as some drop in quality is not noticable in moving images • Trade-off is file size versus image quality. DIGITAL VIDEO COMPRESSION • Common compression standards • MPEG (Motion Picture Experts Group) • JPEG (Joint Photographic Experts Groups) • Cinepak and Sorenson. • MPEG is a real-time video compression algorithm. • MPEG-4 includes numerous multimedia capabilities and is a preferred standard. • MPEG-7 (or Multimedia Content Description Interface) integrates information about motion video elements with their use. • Streaming audio and video starts playback as soon as enough data has transferred to the user’s computer to sustain this playback. EDITING & POST-PRODUCTION 25 223–230 EDITING • Making a constructed whole from a collection of parts • Selection, trimming and organization of raw footage • Apply transitions (e.g. dissolves) between shots • Combination of picture with sound • No changes made to the footage itself SHOOTING AND EDITING VIDEO Shooting & editing video • • • • • • • Shooting platform Storyboard Lighting Chroma Keys Composition Title & Text Nonlinear Editing (NLE) 1. SHOOTING AND EDITING VIDEO Resolution should be reduced and footage must be compressed later according to the requirements. Import video and sound at the highest resolution and with the least amount of compression possible. Good and even lighting is extremely important. Wide panoramic shots and camera motion should be avoided when shooting for a small computer window on CD-ROM or the Web. A steady shooting platform should always be used. Blue screen in digital video editing applications is a popular technique for making multimedia. 2. STORYBOARD A STORYBOARD IS A TOOL FOR SKETCHING OUT HOW A VIDEO WILL UNFOLD, SHOT BY SHOT. IT LOOKS LIKE A COMIC STRIP. 2. STORYBOARD How To Make a Storyboard Step 1: Create a Template Step 2: Add the Script Step 3: Sketch out the story Step 4: Add Notes 3. LIGHTING • Lighting Basics: Backlights, Key Lights, Fill Lights • Backlights: The backlight gives a pleasing depth to the shot and separates your subject from the background. It should be placed behind the subject and should provide light on the head and shoulders. The key light is exactly that, the main light. It should provide the dominant lighting for the subject. • The Fill Light is a supporting light for the key light. It’s usually mirrors the key light at a lower intensity and “fills in” the shadows created by the key light. • Key Lights: These are the main lights used to film the subject of the video. 3. LIGHTING • 3 Basic Camera Angles: Eye, Low, High • Eye level is what’s almost always used in corporate video production. It’s considered neutral and is more flattering than either low or high. It’s also very corporate, and adds little drama to the shoot. It’s the kind of angle you see on the news and romantic comedies. • High angle is shooting down on a person or having the camera significantly higher. Wilde states that this can give the subject a weak or childlike look. This is used in the film industry to illicit that effect. • Low Angle: On the other hand, having the camera significantly lower than the subject and therefore “looking up” at the person creates an intimidating or foreboding look. 4. CHROMA KEY • Chroma keys allow you to choose a color or range of colors that become transparent, allowing the video image to be seen “through” the computer image. 5. COMPOSITION • Composition is how you choose to frame the video you're about to capture; and composition is just as important for video as it is for still photography. • Rule of Thirds • When you look through at your subjects, using Live View on the LCD screen, imagine a tic-tac-toe grid over the scene. • Establishing Shots, Medium Shots, Close-up Shots • Where to Crop or Frame a Shot of a Person • What is Headroom? • Headroom is the amount of space above your subject’s head in a frame. 6. TITLE AND TEXT 6. TITLE AND TEXT 8. NON LINEAR EDITING (NLE) Software: • Adobe Premiere • Apple’s Final Cut • Avid’s Media Composer 8. LINEAR EDITING VIDEO PRODUCTION FLOWCHART 230–236 POST-PRODUCTION • Changing or adding to the material • Most changes are generalizations of image manipulation operations (e.g. colour correction, blurring and sharpening,…) • Compositing – combining elements from different shots into a composite sequence • Animating elements and combining animation with live action 236–237 PREPARING FOR DELIVERY • Compromises required to bring resource requirements of video within capabilities of delivery media (e.g. networks) and low-end machines • Reduce frame size (e.g. downsample to quarter frame) • Reduce frame rate (12fps is OK for smooth motion, flicker not a problem on computer) • Reduce colour depth Digital Multimedia, 2nd edition Nigel Chapman & Jenny Chapman REFERENCES Multimedia Making It Work, Tay Vaughan, 2014, 9th Edition, McGraw Hill. https://yslaiseblog.wordpress.c om/ https://optimus.keycdn.com/su pport/lossy-vs-lossless/ 43