Merging VCube, Руководство пользователя

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Appendices : Glossary Page 281
• conforming: Transferring EDL (Edit Decision List) information gathered from an off-line edit to an on-line
edit for final assembly.
D
• D1: Sony's D1 format was the first major push towards fully digital videotape operations. D1 used a 19mm
(3/4") tape loaded into cassettes as its media. Component video was encoded as YUV 4:2:2 with PCM audio
tracks as well as TimeCode. D1 was notoriously expensive and the equipment required very large infra-
structure changes in facilities which upgraded to this format. Early D1 operations were plagued with diffi-
culties, though the format quickly stabilized and was renowned for its superlative image quality.
• D10: is the SMPTE specification for a professional video format, it is composed of MPEG Video 4:2:2 I-frame
only and8-channel AES3 audio streams. These AES3 audio usually contain 24bit PCM audio samples. It is
possible to find video bit rates of 50, 40 and 30 MBits/s.
• DV: uses DCT (Discrete Cosine Transform) intraframe compression, which is similar to MJPEG, at a fixed bit
rate of 25 Megabit per second, which amounts to roughly 3.6 Megabytes per second or 4 minutes per
Gigabyte. The chroma subsampling is 4:1:1 for NTSC or 4:2:0 for PAL, which reduces the amount of color
resolution stored. Therefore, not all analog formats are outperformed by DV. The lower sampling of the
color space is also a reason why DV is sometimes avoided in applications where chroma-key will be used.
However, a large contingent feel the benefits (no generation loss, small format, digital audio) are an
acceptable trade off given the compromise in color sampling rate. DV allows either 2 digital audio chan-
nels (usually stereo) at 16 bit resolution and 48 kHz sampling rate, or 4 digital audio channels at 12 bit res-
olution and 32 kHz sampling rate. For professional or broadcast applications, 48 kHz is used almost
exclusively. The IEEE 1394 or Firewire serial data transfer bus is not a part of the DV specification, but co-
evolved with it. Nearly all DV cameras have a IEEE 1394 interface and analog composite video and Y/C out-
puts. High end DV VCRs may have additional professional outputs such as SDI, or analog component
video.
• drop-frame TimeCode: SMPTE TimeCode format that continuously counts 30 frames per second but
drops 2 frames from the count every minute except for every tenth minute (drops 108 frames every hour)
to maintain synchronization of TimeCode with clock time. This is necessary because the actual frame rate
of NTSC video is 29.97 frames per second rather than an even 30 frames.
E
• edit decision list (EDL): A list of edit decisions accumulated in a video editor. The list typically includes
the source reel, track(s), in time, and out time and destination track(s) In time and Out time for each edit.
• embedded audio: Digital audio that is multiplexed onto a serial digital video data stream.
• essence: The raw encoded form of audio and video data is often called essence, to distinguish it from the
metadata information that together make up the information content of the stream and any "container"
data that is then added to aid access to or improve the robustness of the stream.
F
• fade: The gradual disappearance of a picture to black (fade, fade-out, fade-to-black), or the gradual
appearance of a new picture from black (fade-in, fade-up).
• field: Half of the interlaced horizontal lines (262.5 in NTSC, 312.5 in PAL) needed to create a complete
frame. A correct field order must be applied to produce a smooth motion. Odd / Upper / Top or Even /
Lower / Bottom are fortunately the two possible solutions.
• flywheel: Condition in which a sync generator has been locked to an outside source, which is no longer
present. Sync generator continues to provide sync on the basis of the last rate received from the outside
source related to its own internal clock. (Mykerinos Internal Clock in Soft chase mode)
• frame: A complete video picture composed of two fields (two complete interlaced scans of the monitor
screen). A frame consists of 525 interlaced horizontal lines of picture information in NTSC, 625 in PAL. In
HD a frame can consist of 720 or 1080 horizontal lines of pixels which may be interlaced or progressive
(non-interlaced).
• free-run: Condition in which a sync generator is not locked to any outside source but is providing sync on
derived from its own internal clock. (Mykerinos Internal Clock)
G
• gen-lock (genlock): To phase-lock the timing of one piece of equipment to another.