Alesis ADAT Manuel du propriétaire télécharger pdf (Page 297)

The Basics

297

Owner’s Manual

Version 1.0 – English -

In Europe 25 fps is used both in the audio ﬁeld and for synchro-

nizing television or video productions.

American audio productions use mainly 30 fps, but with video

the frame rate is nearly always 29.97 df.

International audio productions are recorded with 25 fps, and

30 fps on different tracks.

LTC / VITC

The 80 bits per frame of the SMPTE time code can be stored

in two different forms:

• As a sound signal on a sound track. This is called longitudi-

nal time code (LTC).

• As a signal in the scanning gap of the video picture. (The

complete picture information is transferred slightly quicker

than the duration of a frame. There is a short gap, while the

electronic beam of the cathode ray tube travels from the end

of the bottom line, back to the beginning of the top line.

Because the beam is temporarily switched off, time code

transferred during this gap does not interfere with the

picture.) This is called vertical interval time code (VITC).

LTC is used for all audio productions, and often for video

synchronization as well. Tape duplication plants can record

LTC onto one of the audio tracks, usually track 2. The SMPTE

time can also be written onto the picture. Because of the almost

universal use of LTC for audio work, the term ›SMPTE‹ is

used synonymously with it.

With video synchronization LTC can only be output during

playback at normal speed. VITC (pronounced ›vitzi‹) has the

advantage that it can be output while fast-forwarding, or

rewinding. This is very useful when creating frame-synchro-

nized sound effects, or musical phrases.

 Emagic’s networkable 8x8 Midi interface ›Unitor8‹ has a synchronizer that can read

and write both LTC and VITC.

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Alesis ADAT Manuel du propriétaire Page 297