Lecture

Digital Video

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

horizontal lines of resolutionhorizontal 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.

Factors determining file size in DV

• Resolution (# pixels)

• Frame rate (fps)

• Color Depth (bits)

See p. 15, ch. 1

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

• 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

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 standard 4:1:1 – DVCPro50 4:2:2– Digital S 4:2:2 – HDV 4:2:0– HD Pro 4:2:2– “Red” (HD) 4:4:4 (btw: Red’s res = 4900 x 2980!!!)

Digital Cameras

• CCDCCD- charge coupled device

• CMOS- complementary metal oxide

semiconductor chip

chrominance

• HUE- actual tint

• SITUATION- intensity of color

• LUMINANCE - Brightness; degree of lightness & darkness, amt of B & W

SMPTE Time code

• 03:45:1818:29 Hr :Min: SecSec: Frames

• Drop frame vs. Non-Drop Frame

 

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.)

Focus

• Setting focus

• Racking (pulling) focus)

• Auto? Or not to auto focus?

aperture

• Has adjustable IRIS (diaphragm)

• F-stops: f/1.4 wide open), f/22 (smaller)

• Slow & fast lenses (more light)

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

• 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?

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

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

Shooting multi-cam set upand

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)

Differences between: Standard, DV, HD, Broadcast,

Multimedia, Web video.

• See chapter 1.