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Unit 1 Lesson 01




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    Unit 1 Lesson 01 Unit 1 Lesson 01 Presentation Transcript

    • Lesson 1 Video and Digital Video Basics Digital Video BASICS Schaefermeyer
    • Objectives
      • Explain persistence of vision
      • Explain scanning
      • Describe a cathode ray tube
      • Describe the difference between interlaced and progressive scanning
      • Explain the use of fields and frames
      Schaefermeyer Digital Video BASICS
    • Objectives (continued)
      • Explain time code and how it is used
      • Explain the analog video signal
      • Describe digital video sampling
      • Understand the concept of video formats
      • Explain the differences between DV and other digital formats
      • Understand the concepts of compression and color sampling
      Schaefermeyer Digital Video BASICS
    • Vocabulary
      • Analog
      • Bandwidth
      • Capture card
      • Cathode ray tube (CRT)
      • Chrominance
      • Codec
      • Color sampling
      • Compressed
      • Field
      • FireWire
      • Frame
      • Frame accurate editing
      • Frequency
      • High definition (HD)
      Schaefermeyer Digital Video BASICS
    • Vocabulary (continued)
      • Hue
      • Interlaced video
      • Linear
      • Luminance
      • National Television System Committee (NTSC)
      • Noise
      • Nonlinear
      • Persistence of vision
      • Pixels
      • Progressive scanning
      • Red, green, blue (RGB)
      • Resolution
      • Sampling
      Schaefermeyer Digital Video BASICS
    • Introduction to Video Persistence of Vision
      • The persistence of vision theory states that the human eye holds a still image for a fraction of a second, remaining on the retina long enough to blend with the next image.
      • Film displays 24 still images each second (frames per second or fps).
      Schaefermeyer Digital Video BASICS
    • Introduction to Video Scanning
      • A cathode ray technology (CRT) has two basic parts—an electron gun in back and a screen in front.
      • The inside of the screen is covered with thousands of tiny phosphorus dots called pixels.
      • The back of a color CRT holds three electron guns: red, green, and blue (RGB).
      • The electron gun receives the input signal and shoots an electron beam at the screen, lighting up the pixels.
      Schaefermeyer Digital Video BASICS
    • Scanning (continued)
      • National Television System Committee (NTSC) video is made up of 525 lines of pixels across the screen, called scan lines.
      • The electron beam scans odd scan lines first, to display half a frame called a field.
      • Then the beam scans even lines. Using two fields to create a complete image is called interlaced video.
      • NTSC video runs at 30 frames per second.
      Schaefermeyer Digital Video BASICS
    • Scanning (continued)
      • The delivery methods for video signals have limited bandwidth (size of the “pipe” that information travels through).
      • Progressive scanning creates each frame by scanning the scan lines in order.
      • High definition (HD) uses more scan lines.
      Schaefermeyer Digital Video BASICS
    • Introduction to Video Time Code
      • Each video frame has a unique identifying number called a time code.
      • In the time code 14:54:32:12, 14 represents hours, 54 means minutes, 32 means seconds, and 12 is the frame number.
      • The type of editing made possible by time code is called frame accurate editing.
      Schaefermeyer Digital Video BASICS
    • Introduction to Video Aspect Ratio and Resolution
      • The width of a visible picture is determined by the aspect ratio.
      • The aspect ratio for standard definition television is 4:3, meaning for every four pixels across, there are three pixels up.
      • HD uses a 16:9 aspect ratio and digital video uses a 3:2 aspect ratio.
      Schaefermeyer Digital Video BASICS
    • Aspect Ratio and Resolution (continued)
    • Introduction to Video Analog Versus Digital Signals
      • Audio and video signals that replicate sound or light waves are called analog.
      • Drawbacks to an analog signal:
        • Little glitches called noise, which get worse with each copy (“generational loss”)
        • Linear nature...you can’t jump back and forth
        • Bandwidth issues because it is hard to make smaller
      Schaefermeyer Digital Video BASICS
    • Analog Versus Digital Signals (continued)
      • Digital video solves the problems with analog:
        • Uses a process called sampling so it does not pick up noise in the signal
        • Nonlinear editing system means you do not have to go through the middle to get to the end
        • Can be compressed to get better video quality using the same bandwidth
      Schaefermeyer Digital Video BASICS
    • Introduction to Digital Video DV Format
      • Each digital format has its own language called a codec (short for compression/ decompression”)
      • One way digital video formats compress video is through color sampling—the amount of information used to describe the color in the video image.
      Schaefermeyer Digital Video BASICS
    • DV Format (continued)
      • Light=luminance
      • Hue=specific color such as red, blue, or green
      • Chrominance=amount of saturation
      • Digital video stores all the luminance information and keeps only part of the color information.
      Schaefermeyer Digital Video BASICS
    • Introduction to Digital Video FireWire
      • A capture card converts video into digital information for the computer.
      • DV uses a FireWire capture card, allowing users to capture video through a standard port.
      • A great advantage of DV is that the video comes in as a digital signal and stays that way.
      Schaefermeyer Digital Video BASICS
    • Summary
      • A television contains a cathode ray rube (CRT) with two basic parts. The electron gun in back shoots a beam that lights up pixels, which are organized in scan lines, on the screen in front.
      • One interlaced video frame consists of two fields—the first created by scanning odd numbered lines; the second created by scanning even numbered lines. Video is displayed at 30 fps, or 60 fields per second.
      • A progressive scanned frame of video is scanned in a single pass, with each line scanned in order. Progressive scanned video can be displayed at 24, 30, or 60 fps.
      Schaefermeyer Digital Video BASICS
    • Summary (continued)
      • Analog video copies light waves. Digital video captures points along those waves; the number of points is determined by the sampling frequency.
      • Analog video is linear and cannot be compressed, or made smaller. Digital video is nonlinear and can be compressed.
      • DV captures the video at 3.6 Mb, uses 4:1:1 color space, and is displayed in a 3:2 aspect ratio with a display resolution of 720 x 480.
      • The DV format includes miniDV, DVCPRO, and DVCAM.
      • DV connects to editing stations through FireWire, eliminating the need for expensive capture hardware.
      Schaefermeyer Digital Video BASICS