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multimedia element \ video

multimedia element \ video

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  • 1. By: Taj Elsir Hassan SulimanComputer Department2013MultimediaFundamental concepts in video
  • 2. Video Concept Video is an excellent tool for delivering multimedia. Video places the highest performance demand on computer and itsmemory and storage. Digital video has replaced analog video as the method of choice formaking and delivering video for multimedia.
  • 3. Video Concept Digital video device produces excellent finished products at afraction of the cost of analog. Digital video eliminates the image-degrading analog-to-digitalconversion. Many digital video sources exist, but getting the rights can bedifficult, time-consuming, and expensive.
  • 4. Analogue Video Video information that is stored using television video signals, film,videotape or other non-computer media Each frame is represented by a fluctuating voltage signal known as ananalogue wave form or composite video.
  • 5. Analogue Video Composite analogue video has all the video components: brightness, colour and synchronization Then combined into one signal for delivery Example : traditional television Problems: colour blending, low clarity, high generation lost, difficultto edit.DIGITAL ANALOGUE
  • 6. Digitizing Video Digital video combines features of graphics and audio to createdynamic content for multimedia products. Video is simply moving pictures. Digitized video can be edited more easily. Digitized video files can be extremely large.
  • 7. Digitizing Video Digital video is often used to capture content from movies and television to be usedin multimedia. A video source (video camera ,VCR, TV or videodisc) is connected to a video capturecard in a computer. As the video source is played, the analog signal is sent to the video card andconverted into a digital file (including sound from the video).VCRVideo Overlay Board /Video Capture CardPC
  • 8. Analogue signal from VCRConverted to DIGITALby VIDEO CAPTURE CARDThe convertedsignal isentered inside acomputerSignal is processedVideo is editedusing video editingsoftware software
  • 9. Digital Video Digital video is the digitisation of analogue video signals into numerical format It creates the illusion of full motion by displaying a rapid sequence of changingimages on a display device. Conversion from analogue to digital format requires the use on an ADC (Analogueto Digital Converter) A Digital to Analogue Converter (DAC) can be used to output digital video onanalogue equipment
  • 10. Digital Video Video clip stored on any mass-storage device can be played back on a computer’smonitor without special hardware. Setting up a production environment for making digital video, requires somehardware specifications. Some specifications include computer with FireWire connection and cables, fastprocessor, plenty of RAM, fast and big hard disk.
  • 11. File Size and Formats There is an important consideration: file size in digitized video which included1. frame rate2. image size3. color depth.File Size (bytes)= Frame Size(bytes) x FrameRate (fps) x Video Time(sec)
  • 12. File Size and Formats1. Frame Rate animation is an illusion caused by the rapid display of stillimages. television and movies play at 30 fps but acceptable playbackcan be achieved with 15 fps.
  • 13. File Size and Formats2. Image Size A standard full screen resolution is 640x480 pixels but to safe storingspace a video with 320x240 for a computer display is still acceptable. New high-definition televisions (HDTV) are capable of resolutions upto 1920×1080p60, 1920 pixels per scan line by 1080 scan lines, progressive, at 60frames per second.
  • 14. File Size and Formats3. Color Depth The quality of video is dependent on the color quality (related to thenumber of colors) for each bitmap in the frame sequence.
  • 15. 3. Color Depth The color depth below 256 colors is poorer-quality image. The frame rate to below 15 fps causes a noticeable and distractingjerkiness that unacceptable. Changing the image size and compressing the file therefore becomeprimary ways of reducing file size.File Size and Formats24 bit 8 bit (256 colors)16 bit
  • 16. A video clip is captured with a resolution of320 x 240, and using a color depth of 16bits, the frame rate is 25 fps , and the clip hasa duration of 29 seconds, calculate the filesize of the video clip?Solutions:Give : depth=16 bit (2 bytes), t=29 sec, framerate = 25 fpsExample:
  • 17. Frame Size = Total no of pixels x Depth= 320 x 240 x 2 = 153,600 bytesFile size (bytes) = frame size x frame rate x t= 153600 x 25 x 29 = 111360000 bytesFile size (MB) = 111360000/1024 x 1024= 10.6 MBExample:
  • 18. Video Compression The video compression/decompression programs are used so that video can fit on asingle CD and the speed of transferring video from a CD to the computer can beincreased. Let us say that a sequence of 25fps video is about 25MB. CD-ROM transfer rate is calculated as follows: 1X= 150KB per second 10X=1.5 MB per second 100X= 15 MB per second To overcome large video size, CODECS were developed.Compresseswhen savedCODECFile format usedsuch as: Avi,Mpeg, MovDecompresseswhen needed fordisplay
  • 19. Video Compression Digital video compression schemes or codecs is the algorithm used to compress(code) a video for delivery. The codec then decodes the compressed video in real-time for fast playback. Streaming audio and video starts playback as soon as enough data has transferred tothe user’s computer to sustain this playback.FULLVIDEOTaken from the CDinto memory bufferDISPLAY ONSCREENMEMORY BUFFER
  • 20. Video Compression Two types of COMPRESSION: Lossless compression. Preserves the exact image throughout the compression anddecompression process. E.g: text images is to identifyrepeating words and assign them a code.
  • 21. Video Compression Two types of COMPRESSION: Lossy compression. Eliminates some of the data in the image and thereforeprovides greater compression ratios than losslesscompression. Applied to video because some drop in the quality is notnoticeable in moving images.
  • 22. Video Compression Two types of CODEC (lossy): Spatial compression a digital compression of video data that compresses the size ofthe video file by compressing the image data of each frame Compression is done by removing redundancy from data inthe same frame.
  • 23. Video Compression Two types of CODEC: Temporal compression a digital compression of video data that uses similarities ofsequential frames over time to determine and store only the imagedata that differs from frame to frame. Compression is done by removing similarity between successivevideo frames
  • 24. Video Compression Flavors of file formats brand to choose: Microsoft’s AVI format QuickTime MPEG Div-X Wmv (Windows Media Video)
  • 25. Video Compression Standards have been established for compressionprograms, including JPEG (Joint Photographic ExpertsGroup) and MPEG (Motion Picture Experts Group).
  • 26. JPEG (Spatial) Often areas of an image (especially backgrounds) containsimilar information. JPEG compression identifies these area and stores them as blocksof pixels instead of pixel by pixel reducing the amount ofinformation needed to store the image. These program reduce the file size of graphic images byeliminating redundant information.
  • 27. MPEG (Temporal) The changes in the image from frame to frame. Key frames are identified every few frames thechanges that occur from key frame. Provide greater compression ratios than JPEG. Initially, it requires extra hardware for multimedia.
  • 28. Video Hardware and SoftwareVCRVideo Overlay Board /Video Capture CardVideo digitalEditing SoftwareMULTIMEDIA PC
  • 29. Advantages of using Video Captures interest Increase retention Clarifies complex physical actions and relationships Can incorporate other media
  • 30. Disadvantages of using Video Is expensive to produce Requires extensive memory and storage Requires special equipment Does not effectively illustrate abstract concepts andstatic situations
  • 31. H.W A video clip with size of 45 MB is found in the face book,suppose your friend Taj is going to download it , and he isusing Zain Connect with bandwidth of 2 MB, calculatethe download time?