Unicorn Digital Timepiece, Руководство пользователя, Страница: 42 / 101

F R O N T P A N E L S E T T I N G S
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minute later than the movie. (In fact, upon closer
inspection, you see that audio is slipping by one
entire frame for every thousand frames of film that
go by.)
Why did this happen? Because you recorded
everything while locked to video, which runs at
29.97 — which runs one thousandth (0.1%) slower
than the 30-frame-per-second rate assumed by the
film-to-video transfer.
The Digital Timepiece solves this problem by
allowing you to record audio, while you’re working
with video, at 48kHz
pull-down , a sample rate that
matches the slightly (0.1%) slower speed of video.
When the time comes for you to transfer the audio
back to film, the Digital Timepiece can pull the
audio back up to a true 48kHz (using the straight
48kHz
rate), which makes the audio precisely
match the speed of the film so that it will be in
perfect sync with picture.
The same process can be applied to the base sample
rate of 44.1kHz.
In summary: if you are working with film that has
been transferred to video, set the Digital Timepiece
to a pull-down rate (e.g. 48kHz pull-down) for all
of your recording, editing and mixing to video.
Then, when you are creating your final mix for
transfer back to film (onto DAT or whatever),
switch back to the normal base sample rate (e.g.
48kHz).
Again, the same process can be applied to a base
sample rate of 44.1kHz.
Actual sample rate output
When the Digital Timepiece is put into Internal
time base mode, its actual sample rate output will
always exactly match the word rate setting on its
front panel. The Digital Timepiece has a very
accurate internal clock that ensures an extremely
accurate time base and word clock output.
When the Digital Timepiece is put into one of its
video modes, such as Video/Internal or Video/
SMPTE (LTC) , it derives its time base from
incoming video and internally sets itself to a frame
rate of 29.97 fps for NTSC video and 25 fps for PAL.
As long as the video speed is accurate, the Digital
Timepiece’s actual sample rate output will exactly
match the setting on the front panel.
For time base modes other than Internal or any of
the video modes, the Digital Timepiece’s actual
sample rate output depends on the external time
base. As long as the external time base corresponds
with the front panel settings of the Digital
Timepiece, the Digital Timepiece’s actual sample
rate output will exactly match the setting on its
front panel. But if, for example, the Digital
Timepiece is slaving to SMPTE (LTC), and the
incoming time code is running at 29.97 fps, while
the front panel is set to 30 fps, the Digital
Timepiece’s actual sample rate output won’t match
the front panel word rate setting. In this example, if
the front panel was set to 48kHz (48000), the actual
sample rate output would be 47952 because the
time code is causing the Digital Timepiece to run at
a slower rate.
Below is a chart summarizing the Digital
Timepiece’s actual word clock output in various
situations. The examples in this chart are given at