Apple Final Cut Express 4 - Manual (Page 1065)

Appendix A Video Formats 1065
XIII
Pixels (Samples) per Line
In digital video formats, each line is sampled a number of times. In an attempt to create
a single digital VTR that could digitize and record both NTSC and PAL signals, the
ITU-R BT. 601 specification uses 720 samples per line for both NTSC and PAL video.
Therefore, a digital NTSC video frame is 720 pixels x 486 lines, and a PAL video frame
is 720 pixels x 576 lines.
HD video with 1080 lines uses 1920 pixels per line (1920 x 1080). 720-line HD video uses
1280 pixels per line (1280 x 720). Both of these formats have an aspect ratio of 16:9.
Common video frame sizes are shown in the table below.
Width Height
Pixel
aspect ratio Screen
aspect ratio
Description
320 240 1:1 4:3 Used for web distribution or offline
video editing.
640 480 1:1 4:3 An early standard for analog-to-digital
video editing, and an ATSC video
specification.
720 1 480 Height greater
than width 4:3 NTSC DV and DVD image dimensions.
Also part of the ATSC video
specification.
720 1 486 Height greater
than width 4:3 NTSC SD video dimensions used for
professional digital formats such as
Digital Betacam, D-1, and D-5.
720 1 576 Width greater
than height 4:3 PAL SD video dimensions used for
digital formats such as Digital
Betacam, D-1, and D-5, as well as
DVD and DV.
1280 720 1:1 16:9 An HD video format, capable of
higher frame rates in exchange for
smaller image dimensions.
1920 1080 1:1 16:9 An HD video format with very
high resolution.
960 720 4:3 16:9 Some 720p formats (such as
DVCPRO HD and HDV) subsample
1280 pixels to 960 to minimize the
data rate.
1440
1280 1080 4:3
3:2 16:9 Some 1080-line formats (such as HDV
and DVCPRO HD) subsample 1920
pixels to 1440 or even 1280 to
minimize the data rate.
1 In most video devices, only 704 or 708 pixels are actually used for picture information.