IT Schweber Chap 141 No pain that we suffer, no trial that we experience is wasted. It ministers to our education, to the development of such qualities as patience, faith, fortitude and humility. All that we suffer and all that we endure, especially when we endure it patiently, builds up our characters, purifies our hearts, expands our souls, and makes us more tender and charitable, more worthy to be called the children of God. Elder Orson F. Whitney ( )
IT Schweber Chap 142
TV/Video: A Legacy System Par Excelance Really Old B&W TV, NTSC (≈1940) Color, NTSC (≈1950) B&W Movies (≈1910) Color Movies (≈1950) More Recent HDTV (≈2000) MP4 (≈1990)
TV: The Camera
TV: The Screen 525 lines 384 pixels/line = 201,600 pixels 30 frames/sec Interleaved from 2 fields per frame 30 f/s * 201,600 pixels/frame = 6,048,000 pixels/sec
TV: Color Standards & Pixels
TV: Color Pixels
TV: The Signal (Time Domain) Very tight tolerances on timing, frequency High tolerance for poor signal
TV: The Signal (Frequency Domain) Video: AM, vestigial sideband Frequency- multiplexed sub- carriers Audio: FM, narrow- band
TV: The Receiver
Just the fax, please No gray scale: 1 = black, 0 = white At 200 pels/inch and 200 line/inch = 1700 x 2200 = 3.74 Mbits/page At 4800 bps = 13 min/pg = impractical Uses very significant spatial compression
But what if you can’t compress it? Andrew Jorgensen; Fall 2003 ORR substitute Pseudorandom pattern Cannot be spatially compressed 12 minutes, then crashed
Compression Lossy MPEG, MP3, JPG, GIF, MP4, OGG Compression ratios from 2:1 to 1000:1 Irreversible loss in quality, data Lossless ZIP, PNG, RAW, BMP, WAV, WMV Compression ratios from 1.1:1 to 2:1 Original data not lost and can be completely restored Methods of compression Mathematical Spatial Temporal x 1920 p = 2,073,600 pixels/frame; x 3 subpixels = 6,220,800 subpixels x 60 frames/second x 8 bits/subpixel = Gbps (native) The magic of compression
Mathematical Compression
Compression Artifacts