Unicorn Digital Timepiece, Руководство пользователя

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F R O N T P A N E L S E T T I N G S
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THE WORD CLOCK RATE SETTING
To set the word clock rate (i.e. the sample rate ), use
the RATE button on the Digital Timepiece front
panel as shown below in Figure 4-5.
Figure 4-5: Setting the sample rate manually using the controls on
the Digital Timepiece front panel. This is only necessary for the time
base modes listed earlier in this section. For any time base mode that
relies on an external word clock time base source, the Digital
Timepiece automatically detects the sample rate.
You can also set the sample rate using the Digital
Timepiece software, called
ClockWorks . In
ClockWorks, open the MIDI Machine Control
window from the Windows menu. Open the extra
settings panel as shown below in Figure 4-6, and
then choose the frame rate from the pop-up menu
provided. For more information about
ClockWorks, see the
ClockWorks User’s Guide that
accompanies this manual.
Figure 4-6: Setting the sample rate in ClockWorks software.
Using pull-up and pull-down
The pull-up and pull-down sample rate settings
speed up or slow down the sample rate by 0.1%.
For example, a sample rate of 48kHz plays 48,000
samples per second. 48kHz pull-down plays only
47,952 samples per second. (The difference is 48
samples, which is 0.1% of 48,000.)
The pull-up/down sample rates are most
commonly needed when working with film that
has been transferred to video for audio post
production, where the audio will be transferred
back to film again. The pull-up/down features of
the Digital Timepiece help the audio play back at
the correct speed, even after it has been transferred
back to film.
Here is a brief, simplified explanation. Film runs at
24 frames per second. Video runs at 30 frames per
second —
almost , that is. NTSC video actually runs
at 29.97 frames per second, which is 0.1% slower
than 30 frames per second. To keep things from
getting ridiculously complicated, film is
customarily transferred to video (in a process
called
telecining ) by mapping every 24 frames of
film to 30 frames of video. But since the resulting
video is actually played back at 29.97, the picture
actually runs 0.1% slower than it does on film.
Let’s say, for the sake of this simplified example,
that you have shot a film that is exactly 1,000
minutes long. (Perhaps you just couldn’t bring
yourself to cut any of the original footage.) When
you transfer the film to video and then play it back
on a video deck, the actual elapsed time to play the
film in its entirety will now be 1,001 minutes, due
to the 0.1% slower speed of video.
Now let’s say that you record all kinds of audio
while slaved to the video — music, dialog, effects,
etc. — at 48kHz. The result is a final stereo audio
mix that is 1,001 minutes long and that perfectly
matches the video frame per frame (and SMPTE
hit for SMPTE hit). So far, so good.
But now you try to simply dub your 48kHz mix
back onto film. And you are shocked and angered
as you realize that your audio no longer matches
the film. The audio mix is 1,001 minutes long, but
your movie is only 1,000 minutes long! The audio
starts out in sync with the movie, but it slowly
drifts out of sync with picture and ends one entire
Extra settings button in the
MIDI Machine Control window