Instruction Manual

Chapter 26 Video and le formats 1055
Note: Uncompressed 8-bit and 10-bit 4:2:2 movies do not support alpha channels.
DVCPRO HD
A high-denition video format used to capture video digitally from FireWire-enabled DVCPRO HD
compatible decks. (Not to be confused with DVCPRO 25 or DVCPRO 50, which are both standard-
denition formats.) This format supports a number of frame sizes and frame rates, including a
24p format that oers variable speed via a variable frame rate technology. DVCPRO HD uses 4:2:2
color sampling for high color delity, and has a xed data rate of 12.5 MB/sec.
Note: DVCPRO HD movies do not support alpha channels.
DVCPRO 50
A standard-denition codec used to capture video digitally from FireWire-enabled,
DVCPRO 50-compatible camcorders and decks. Although it’s similar to the DV codec because
DVCPRO 50 is imported as YUV encoded video, it produces considerably higher quality video
because it uses less compression. (DVCPRO 50 uses a 3:3:1 compression ratio, versus DV’s 5:1
compression ratio.) DVCPRO 50 also uses 4:2:2 color sampling for high color delity, as opposed
to DV’s 4:1:1 color sample rate. DVCPRO 50 has a xed data rate of 7 MB/sec.
Note: DVCPRO 50 movies do not support alpha channels.
Third-party codecs
Numerous video-editing solutions use dierent codecs, some of which may be available for
installation to encourage interoperability. For more information, contact the manufacturer of the
editing system.
Note: Most third-party codecs cannot have alpha channels.
Field order
When a video display is fed an interlaced video signal, each frame of video is split into two elds,
each of which contains a set of alternating lines of horizontal resolution running across the
screen. Standard-denition NTSC and PAL are both interlaced video formats, while some high-
denition video formats, and all video displayed on a computer screen, are progressive-scanned
video formats. With progressive scanning, these lines are drawn one at a time, from the top of
the screen to the bottom.
When you record interlaced footage with a camcorder, each video frame is split into two elds,
each containing half of the total lines of resolution in the frame. The rst eld is recorded, then
the second, one after the other, so both elds constitute one frame. When you play the video
back, the monitor displays each recorded frame in succession, rst drawing one eld, then
the other.
Field order refers to the order in which each pair of video elds is recorded. Because video elds
are recorded sequentially, it’s as if each 29.97 fps clip is really playing at 60 “frames” per second.
There are two options for eld order:
•
Upper (Field 2 is dominant, so the second eld is drawn rst.)
•
Lower (Field 1 is dominant, so the rst eld is drawn rst.)
Generally, Upper is used by 640 x 480 systems, while Lower is most common in professional
720 x 486 and DV 720 x 480 systems.
67% resize factor