Apple Final Cut Express 4 - Manual (Page 1070)

1070 Part XIII Appendixes
Color Recording Method
The color recording method of a video format may be either RGB, Y´C
B
C
R
(component),
Y/C (S-Video), or composite. The more discrete channels a format has, the higher the
quality of the image, but the more data required to store and transmit that information.
Today, almost all digital video formats are Y´C
B
C
R
(component). Computers typically
store image data using RGB, although many Y´C
B
C
R
(component) formats can now be
processed natively on the computer (such as DV).
Video Sample Rate and Bit Depth
The video sample rate of a digital video format determines how often the light
intensity of each video line is sampled.
Color recording method Video formats
Composite 1", 3/4" U-matic, 1/2",VHS, D-2, D-3
Y/C (S-Video) Hi8, S-VHS
Y´C
B
C
R
(component) Betacam SP, Digital Betacam, DVD, DV, D-1, D-5
RGB Computer graphics and digital cinema acquisition. Although video
originates in and is displayed in this format, it is rare for tape
formats (Y´C
B
C
R
is used instead).
Sample rate Description
74.25 MHz HD video luma (Y´) sample rate.
37.125 MHz HD video chroma (C
B
C
R
) sample rate. This is half of the luma sample
rate, used for 4:2:2 HD video.
14.3 MHz Early NTSC digital video recorders sampled video at exactly four
times the frequency of the color subcarrier signal (3.58 MHz x 4).
This is the origin of the 4 in color sample ratios such as 4:2:2.
13.5 MHz This is the sample rate for the luma (Y´) channel for SD digital video.
This sample rate was chosen to work with both NTSC and PAL digital
video. The 4 in 4:2:2 is now represented by this sample rate.
6.75 MHz This is the sample rate for the color difference channels in 4:2:2
video. This is half of 13.5 MHz.