Specifications

7
A Digital Video Primer
Today, as a result of the popularity of letterboxed lms on DVD, broadcast TV, and HDTV, many
new televisions come with wider screens. e aspect ratio of widescreen TV is 16:9 (1.78), which
is well-suited for the most-popular lm aspect ratio of 1.85. For movies with wider aspect ratios,
such as 2.35:1, the new TVs display narrow letterbox bars.
FO RM AT ASPEC T R ATIO HO R IZO NTAL
RE S OLU TI O N
PI XE LS/L IN E
VE R TI C AL RES O 
LUT ION S CAN
LI NE S
FR AME R AT E/
IN TE R L ACE D O R
PROG R ESSI VE
BI T R ATE
ME GA BI TS PER
SECON D
NTSC (USA, Canada, Japan, Korea,
Mexico)
4:3 330* 525 (480 visible) 30i N/A
PAL (Australia, China, most of Europe,
South America)
4:3 330* 625 (576 visible) 25i N/A
SECAM (France, Middle East, much
of Africa)
4:3 330* 625 (576 visible) 25i N/A
24P 18 Mbps
HDTV 16:9 1920 1080 30p 18 Mbps
30i 18 Mbps
24P 8 Mbps
HDTV 16:9 1280 720 30p 10 Mbps
60p 18 Mbps
24P 3 Mbps
SDTV 16:9 720 483 30p 30i 4 Mbps 4 Mbps
60p 8 Mbps
24P 3 Mbps
SDTV 4:3 720 486 30p 30i 4 Mbps 4 Mbps
60p 7 Mbps
24P 3 Mbps
SDTV 4:3 640 480 30p 30i 3 Mbps 3 Mbps
60p 7 Mbps
*330 lines of resolution assumes that the bandwidth of the analog video signal has been limited to 4.2MHz for transmission over the air.
Video color systems
Most of us are familiar with the concept of RGB color, referring to the red, green, and blue
components of a color. Each pixel we see is actually the product of the light coming from a red,
a green, and a blue phosphor. Because the phosphors are very small and placed close together,
our eyes blend the primary light colors into a single color. e three color components are oen
referred to as the channels.
Computers typically store and transmit color with 8 bits of information for each of the red,
green, and blue components. With these 24 bits (2
24
) of information, over 16 million dierent
variations of color can be represented for each pixel. In the computer world, this type of repre-
sentation is known as 24-bit color; in the video industry, it is referred to as 8-bit-per-channel
color.
While 8-bit-per-channel color is in common use, much of today’s high-end professional hardware
and soware deliver even higher quality color with 10-bit-per-channel color. An 8-bit number
(2
8
) has 256 possible values, while a 10-bit number (2
10
) has 1024 possible values. erefore,
10-bit-per-channel color has the potential for as much as four times the color resolution of 8-bit
color. If you are concerned with the very highest quality output, you can even work in 32-bit-per-
channel color in Aer Eects. When you work with high-resolution images that use a wide range
of colors, such as when you’re creating lm eects or output for HDTV, the dierence is easily
visible. Gradual transitions between colors are smoother with less visible banding, and more
detail is preserved, which is critical when applying lters and special eects.
Broadcast standards including the 18 DTV options authorized in the U.S. by the FCC.