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Chapter 6: video. ITBIS351 Multimedia Systems and Hypermedia Yaqoob Al- Slaise. Outline. video. Of all the multimedia elements, video places the highest performance demand on your computer or device—and its memory and storage. How video works.
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Chapter 6: video ITBIS351 Multimedia Systems and Hypermedia Yaqoob Al-Slaise
video • Of all the multimedia elements, video places the highest performance demand on your computer or device—and its memory and storage.
How video works • When light reflected from an object passes through a video camera lens, that light is converted into an electronic signal by a special sensor called a charge-coupled device (CCD)
ANALOG video • Analog video has a resolution measured in the number of horizontal scan lines (due to the nature of early cathode-tube cameras).
Video standards (Component) • Component: Separates the Red, Green, Blue channels on different CCDs as separate signals on its own conductor. • Component is used for high quality video.
S-video • S-Video: (Separate Video) uses two channels: • Luminance: sometimes referred as Y (greyscale). • Chrominance: sometimes referred as C (color)
composite • Composite: when all the signals are mixed together and carried on a single cable as a composite of the three color channels and the sync signal. The composite signal yields less-precise color definition.
Helical scan • A single video frame is made up of two fields that are interlaced. • Tracking is the fine adjustment of the tape during playback so that the tracks are properly aligned as the tape moves across the playback head.
Analog Broadcast Standards • NTSC • National Television Standards Committee • a single frame of video was made up of 525 horizontal scan lines drawn onto the inside face of a phosphor-coated picture tube every 1/30th of a second by a fast-moving electron beam. • Odd lines than even lines (60 lines per second= 60Hz)
Analog broadcast standards • PAL • Phase Alternate Line (PAL) • increased the screen resolution to 625 horizontal lines, but slowed the scan rate to 25 frames per second. • 50 lines per second = 50Hz
Analog broadcast standards • SECAM • Sequential Color and Memory (SECAM) • a 625-line, 50 Hz system. • SECAM transmits only one color at a time, it is free of the color artifacts present in NTSC and PAL resulting from the combined transmission of both signals.
hdtv • HDTV provides high resolution in a 16:9 aspect ratio. • The broadcast industry promulgated an ultra-high-resolution, 1920 × 1080 interlaced format (1080i). • BUT the computer industry wanted a 1280 × 720 progressive-scan system (720p) for HDTV. • Both formats have been included in the HDTV standard by the Advanced Television Systems Committee (ATSC).
displays • cathode ray tube (CRT): Colored phosphorsscreen glow red, green, or blue when they are energized by an electron beam.
Flat screen • Liquid-crystal display (LCD) is a flat panel display, electronic visual display, or video display that uses the light modulating properties of liquid crystals. Liquid crystals do not emit light directly. • Plasma: the technology utilizes small cells containing electrically charged ionized gases, or what are in essence chambers more commonly known as fluorescent lamps.
Shooting and editing video • Fast processor(s) • Plenty of RAM • Computer with FireWire (IEEE 1394 or i.Link) or USB connection and cables • Fast and big hard disk(s) • A second display to allow for more real estate for your editing software • External speakers • Nonlinear editing (NLE) software
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.
