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  1. 1. Introduction to Multimedia <ul><li>SMM 2005 </li></ul><ul><li>Muhd. Nabil Ahmad Zawawi </li></ul><ul><li>Jabatan Multimedia, FSKTM, UPM </li></ul><ul><li>[email_address] </li></ul><ul><li>03-89466526 </li></ul><ul><li> </li></ul>
  2. 2. Introduction to Multimedia <ul><li>Chapter 6 </li></ul>VIDEO
  3. 3. 6.1 Video Concept <ul><li>Video is an excellent tool for delivering multimedia. </li></ul><ul><li>Video places the highest performance demand on computer and its memory and storage. </li></ul><ul><li>Digital video has replaced analog video as the method of choice for making and delivering video for multimedia. </li></ul>
  4. 4. 6.1 Video Concept <ul><li>Digital video device produces excellent finished products at a fraction of the cost of analog. </li></ul><ul><li>Digital video eliminates the image-degrading analog-to-digital conversion. </li></ul><ul><li>Many digital video sources exist, but getting the rights can be difficult, time-consuming, and expensive. </li></ul>
  5. 5. 6.2 Analogue Video <ul><li>Video information that is stored using television video signals, film, videotape or other non-computer media </li></ul><ul><li>Each frame is represented by a fluctuating voltage signal known as an analogue wave form or composite video. </li></ul>
  6. 6. 6.2 Analogue Video <ul><li>Composite analogue video has all the video components: </li></ul><ul><ul><li>brightness, colour and synchronization </li></ul></ul><ul><li>Then combined into one signal for delivery </li></ul><ul><li>Example : traditional television </li></ul><ul><li>Problems: colour blending, low clarity, high generation lost, difficult to edit. </li></ul>DIGITAL ANALOGUE
  7. 7. Digitizing Video <ul><li>Digital video combines features of graphics and audio to create dynamic content for multimedia products. </li></ul><ul><li>Video is simply moving pictures. </li></ul><ul><li>Digitized video can be edited more easily. </li></ul><ul><li>Digitized video files can be extremely large. </li></ul>
  8. 8. Digitizing Video <ul><li>Digital video is often used to capture content from movies and television to be used in multimedia. </li></ul><ul><li>A video source (video camera ,VCR, TV or videodisc) is connected to a video capture card in a computer. </li></ul><ul><li>As the video source is played, the analog signal is sent to the video card and converted into a digital file (including sound from the video). </li></ul>Video Overlay Board / Video Capture Card <ul><ul><li>PC </li></ul></ul>VCR
  9. 9. Analogue signal from VCR Converted to DIGITAL by VIDEO CAPTURE CARD The converted signal is entered inside a computer Signal is processed Video is edited using video editing software software
  10. 10. 6.3 Digital Video <ul><li>Digital video is the digitisation of analogue video signals into numerical format </li></ul><ul><li>It creates the illusion of full motion by displaying a rapid sequence of changing images on a display device. </li></ul><ul><li>Conversion from analogue to digital format requires the use on an ADC (Analogue to Digital Converter) </li></ul><ul><li>A Digital to Analogue Converter (DAC) can be used to output digital video on analogue equipment </li></ul>
  11. 11. 6.3 Digital Video <ul><li>Video clip stored on any mass-storage device can be played back on a computer’s monitor without special hardware. </li></ul><ul><li>Setting up a production environment for making digital video, requires some hardware specifications. </li></ul><ul><li>Some specifications include computer with FireWire connection and cables, fast processor, plenty of RAM, fast and big hard disk. </li></ul>
  12. 12. File Size and Formats <ul><li>There is an important consideration: </li></ul><ul><ul><li>file size in digitized video which included </li></ul></ul><ul><ul><ul><li>frame rate </li></ul></ul></ul><ul><ul><ul><li>image size </li></ul></ul></ul><ul><ul><ul><li>color depth. </li></ul></ul></ul>
  13. 13. File Size and Formats <ul><li>Frame Rate </li></ul><ul><ul><li>animation is an illusion caused by the rapid display of still images. </li></ul></ul><ul><ul><li>television and movies play at 30 fps but acceptable playback can be achieved with 15 fps. </li></ul></ul>
  14. 14. File Size and Formats <ul><li>Image Size </li></ul><ul><ul><li>A standard full screen resolution is 640x480 pixels but to safe storing space a video with 320x240 for a computer display is still acceptable. </li></ul></ul><ul><ul><li>New high-definition televisions ( HDTV ) are capable of resolutions up to 1920×1080p60 , </li></ul></ul><ul><ul><ul><li>1920 pixels per scan line by 1080 scan lines, progressive, at 60 frames per second. </li></ul></ul></ul>
  15. 15. File Size and Formats <ul><li>Color Depth </li></ul><ul><ul><li>The quality of video is dependent on the color quality (related to the number of colors) for each bitmap in the frame sequence. </li></ul></ul>
  16. 16. <ul><li>Color Depth </li></ul><ul><ul><li>The color depth below 256 colors is poorer-quality image. </li></ul></ul><ul><ul><li>The frame rate to below 15 fps causes a noticeable and distracting jerkiness that unacceptable. </li></ul></ul><ul><ul><li>Changing the image size and compressing the file therefore become primary ways of reducing file size. </li></ul></ul>File Size and Formats 24 bit 8 bit (256 colors) 16 bit
  17. 17. Video Editing Terminology <ul><li>Linear </li></ul><ul><ul><li>It plays end to end in one direction, usually pertains to videotape editing specifically the editing of linear tape segments into one final master tape. </li></ul></ul>
  18. 18. Video Editing Terminology <ul><li>Non-linear </li></ul><ul><ul><li>Refers to the editing of disk-based digital video. </li></ul></ul><ul><ul><li>The software provides an on screen map of what the final video sequences should look like incorporating the edits, splices, special effects, transitions and sound tracks. </li></ul></ul>
  19. 19. Special Effects <ul><li>Transitions </li></ul><ul><ul><li>Such as fading, wiping, splatters, scrolling, stipple and many more are available by simply dragging and dropping that transition between the two video clips. </li></ul></ul>
  20. 20. Special Effects <ul><li>Superimposing </li></ul><ul><ul><li>The ability to superimpose one clip over another is a valuable technique. </li></ul></ul><ul><ul><li>The technique of green screening is identical except that the color green is used for the screen and later digitally removed. </li></ul></ul><ul><ul><li>The blue screen and green screen superimposing are just two of the superimposing technique available. </li></ul></ul>
  21. 21. Special Effects <ul><li>Superimposing </li></ul><ul><ul><li>Digital video editing applications provide special effect filters to create lens flares and emboss, tint, pan, twist and zoom the video image. </li></ul></ul><ul><ul><li>These special effects can often be set up to change over the duration of the video clip. </li></ul></ul>
  22. 22. 6.4 Video Compression <ul><li>The video compression/decompression programs are used so that video can fit on a single CD and the speed of transferring video from a CD to the computer can be increased. </li></ul><ul><li>Let us say that a sequence of 25fps video is about 25MB. </li></ul><ul><li>CD-ROM transfer rate is calculated as follows: </li></ul><ul><ul><li>1X= 150KB per second </li></ul></ul><ul><ul><li>10X=1.5 MB per second </li></ul></ul><ul><ul><li>100X= 15 MB per secondt </li></ul></ul><ul><li>To overcome large video size, CODECS were developed. </li></ul>Compresses when saved CODEC File format used such as: Avi, Mpeg, Mov Decompresses when needed for display
  23. 23. 6.4 Video Compression <ul><li>Digital video compression schemes or codecs is the algorithm used to compress (code) a video for delivery. </li></ul><ul><li>The codec then decodes the compressed video in real-time for fast playback. </li></ul><ul><li>Streaming audio and video starts playback as soon as enough data has transferred to the user’s computer to sustain this playback. </li></ul>FULL VIDEO Taken from the CD into memory buffer DISPLAY ON SCREEN MEMORY BUFFER
  24. 24. 6.4 Video Compression <ul><li>Two types of COMPRESSION: </li></ul><ul><ul><li>Lossless compression. </li></ul></ul><ul><ul><ul><li>Preserves the exact image throughout the compression and decompression process. E.g: text images is to identify repeating words and assign them a code. </li></ul></ul></ul>
  25. 25. 6.4 Video Compression <ul><li>Two types of COMPRESSION: </li></ul><ul><ul><li>Lossy compression. </li></ul></ul><ul><ul><ul><li>Eliminates some of the data in the image and therefore provides greater compression ratios than lossless compression. </li></ul></ul></ul><ul><ul><ul><li>Applied to video because some drop in the quality is not noticeable in moving images. </li></ul></ul></ul>
  26. 26. 6.4 Video Compression <ul><li>Two types of CODEC (lossy): </li></ul><ul><ul><li>Spatial compression </li></ul></ul><ul><ul><ul><li>a digital compression of video data that compresses the size of the video file by compressing the image data of each frame </li></ul></ul></ul><ul><ul><ul><li>Compression is done by removing redundancy from data in the same frame. </li></ul></ul></ul>
  27. 27. 6.4 Video Compression <ul><li>Two types of CODEC: </li></ul><ul><ul><li>Temporal compression </li></ul></ul><ul><ul><ul><li>a digital compression of video data that uses similarities of sequential frames over time to determine and store only the image data that differs from frame to frame. </li></ul></ul></ul><ul><ul><ul><li>Compression is done by removing similarity between successive video frames </li></ul></ul></ul>
  28. 28. 6.4 Video Compression <ul><li>Flavors of file formats brand to choose: </li></ul><ul><ul><li>Microsoft’s AVI format </li></ul></ul><ul><ul><li>QuickTime </li></ul></ul><ul><ul><li>MPEG </li></ul></ul><ul><ul><li>Div-X </li></ul></ul><ul><ul><li>Wmv (Windows Media Video) </li></ul></ul>
  29. 29. 6.4 Video Compression <ul><li>Standards have been established for compression programs, including JPEG (Joint Photographic Experts Group) and MPEG (Motion Picture Experts Group). </li></ul>
  30. 30. JPEG (Spatial) <ul><li>Often areas of an image (especially backgrounds) contain similar information. </li></ul><ul><li>JPEG compression identifies these area and stores them as blocks of pixels instead of pixel by pixel reducing the amount of information needed to store the image. </li></ul><ul><li>These program reduce the file size of graphic images by eliminating redundant information. </li></ul>
  31. 31. MPEG (Temporal) <ul><li>The changes in the image from frame to frame. </li></ul><ul><li>Key frames are identified every few frames the changes that occur from key frame. </li></ul><ul><li>Provide greater compression ratios than JPEG. </li></ul><ul><li>Initially, it requires extra hardware for multimedia. </li></ul>
  32. 32. Video Hardware and Software Video Overlay Board / Video Capture Card Video digital Editing Software MULTIMEDIA PC VCR
  33. 33. Video Editing Software <ul><li>Incorporating transitions such as dissolves, wipes and spin. </li></ul><ul><li>Superimposing titles and animating them, such as fly-in logo. </li></ul><ul><li>Applying special effects to various images, such as twisting, zooming, rotating and distorting. </li></ul><ul><li>Synchronizing sound with the video. </li></ul><ul><li>Apply filters that control color balance, brightness & contrast, blurring, distortions and morphing. </li></ul>
  34. 34. Advantages of using Video <ul><li>Captures interest </li></ul><ul><li>Increase retention </li></ul><ul><li>Clarifies complex physical actions and relationships </li></ul><ul><li>Can incorporate other media </li></ul>
  35. 35. Disadvantages of using Video <ul><li>Is expensive to produce </li></ul><ul><li>Requires extensive memory and storage </li></ul><ul><li>Requires special equipment </li></ul><ul><li>Does not effectively illustrate abstract concepts and static situations </li></ul>
  36. 36. Summary <ul><li>Digital video method is used for making and delivering video for multimedia. </li></ul><ul><li>Compression techniques help to reduce the file sizes to more manageable levels </li></ul><ul><li>Two types of compression lossless and lossy. </li></ul><ul><li>Standards for compression program are JPEG and MPEG. </li></ul>