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Lecture Digital Video
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Scanning vs. aspect ratio SDTV –525 (vertical) res of interlaced scanned lines (actually 300x480) –Aspect ratio of 4:3 HDTV –Most prevalent: 720p (ABC, Fox) or 1080i (NBC, CBS) –Also 1125, plus 1080 and more (“RED” camera 4900 x 2980 !) –Aspect ratio of 16:9 24 p: 24 fps –Refers to frames per second lines of resolution can be varies: ex, 1920 x 1080, 1280 x 720, 1440 x 1080 –More film-like (do you know why?) –Can generate masters for SD, DV and HD due to its high quality. HDV: –16:9 –Both 720p & 1080i
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horizontal lines of resolution This refers to the number of horizontal lines within each frame. The higher the number– the better the clarity and definition of the picture.
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Factors determining file size in DV Resolution (# pixels) Frame rate (fps) Color Depth (bits) See p. 15, ch. 1
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Resolution –How SHARP the image is –Determined by the number of pixels seen ACROSS the screen: HORIZONTAL resolution. –Is NOT same as video /TV “scanning” –Horizontal scanning depends on to some degree quality of TV set –The higher the resolution, the better Standard ANALOGUE TV: 4:3; 640 x 480 DV: 4:3 or 16:9; HD & HDV: 1280 x 720 720 (30p;) 1440 x 1080(60i); 1920x 1080i
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Compression: –reduces amt of space need to store video data & move across bandwidth –Lossless –Lossy –Codecs –Compression Ratio Higher the ratio, the more compression allowing more info but also lower quality. DV/DVCAM: compression of 5:1
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Color Sampling Drop out: loss of signal due to imperfections on tape Color sampling- also expressed as a ratio –Color sampling is, in effect, a form of compression. –Luminance (y): color (ry): color (by) –Since the human visual system is much more sensitive to variations in brightness than color, a video system can be optimized by devoting more bandwidth to Y' than the color difference components Cb and Cr. 4:2:0 > two channels of component color info (2) are sampled at half the resolution of the brightness info (4) [every 4 x color is sampled, brightness is sampled twice] 4:4:4 > Full resolution color Every 4x brightness info is sampled, brightness is sampled 4x. –DV standard4:1:1 – DVCPro504:2:2 –Digital S4:2:2 –HDV4:2:0 – HD Pro4:2:2 – “Red” (HD)4:4:4 (btw: Red’s res = 4900 x 2980!!!)
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Digital Cameras CCDCCD- charge coupled device CMOS- complementary metal oxide semiconductor chip
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chrominance HUE- actual tint SITUATION- intensity of color LUMINANCE - Brightness; degree of lightness & darkness, amt of B & W
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SMPTE Time code 1803:45:18:29 Sec Hr :Min: Sec: Frames Drop frame vs. Non-Drop Frame
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Lenses Focal length: fixed vs. variable (zoom) Zoom ratio: 10:1 If widest shot is 20 mm, tightest shot is 200mm 20X Zoom Makes subject appear 20 times closer than it actually is in reality. Macro setting: VERY close! Use for tiny subjects (bugs, surgery, how to videos, etc.--for extremely small items w/ extreme close ups.)
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Focus Setting focus Racking (pulling) focus) Auto? Or not to auto focus?
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aperture Has adjustable IRIS (diaphragm) F-stops: f/1.4 wide open), f/22 (smaller) Slow & fast lenses (more light)
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Depth of field Range of what objects are in sharp focus Varies: –Aperture (f-stop) –Camera-subject distance (closer the subject, the less DoF –Focal length of lens –Example: The longer the focal length, wider the aperture, shallower the depth of field. –Wide-angle: greater DoF –A lens set at f/22 will create greater DoF than f/2.8
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Shot->scene->sequence Mise-en-scene: –composition –Framing Basic shots: XCU, CU, MS, LS, XLS Subjective shots: POV shot, OS Cam Angle: 5 diff. angles. What are they?
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Composing within static frame Blocking Balance Creating depth; z-axis Rule of thirds Shot duration: longer on frame affects how audience sees it & understands it 30 degree rule-avoids jump cuts
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Composing for the moving frame Don’t be afraid to let subject arrive-leave frame Don’t shoot everything, every moment! Camera movement –Pan –Tilt –Dolly –Tracking –Crane (boom) –Arc
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Shooting multi-cam set up and Shooting to Edit Three basic style of coverage –Classical, contemporary, personal ….See other PPTs on Directing for Form & Content ( : Shooting for continuity –180 degree rule-continuity of action –Also, see other PPTs on Directing for Form & Content)
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Differences between: Standard, DV, HD, Broadcast, Multimedia, Web video. See chapter 1.
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