[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: sync sound with undercrank



>My client wants to undercrank the film while shooting, for playback in
>telecine at 24 fps, to create a 'sped-up' look.  I assume this
>shooting speed would be somewhere around 18-20 fps.
>
>He wants to shoot sync sound.  Can someone recommend a way to do this?
>
>--Rob
Sync sound is nothing more than two independent clocks running at a nominal
rate while capturing the information stream. The post production process
then references each source to a clock running at the _assumed_ nominal,
common rate. This fails to be synchronous only when one of the two capture
clocks is running at an unexpected rate.

You want the look of under cranked film but you don't really want a time
shift (I assume.) This would be more of a strobe effect (with extra image
lag due to longer integration time.) The rate of the action should still
stay in sync if you select camera speeds that have the same relationship to
your available playback rates that the "sound speed" does to 23.98 transfer
rate. If the desired look is right at 18 fps, pick a transfer speed on the
telecine (18.03 on a Rank if memory serves) multiply by 1.001 and ask the
camera operator to dial this in as closely as possible. There are crystal
sync units for cameras that have this type of precision. VariSpeed rates
with 4 digits of precision are accurate to within 0.06 to 0.03% of the
actual speed of the rank. This is about twice as good as 1 part per
thousand of the simple crystal that may be in the audio recorder or camera.
If you want more accuracy on the VariSpeed rates, I have a chart around
somewhere that calculates the rate out to 6 or 7 decimal places.

If you want the time shift but need to stay in sync with an existing track,
some element of the shoot (a singer?) will still need to use a guide for
pacing. If they are shooting to audio playback, the playback would need to
be slowed down the same amount as the camera for the performer to sync to.
When the audio track was restored to normal speed in the transfer, the
normal transfer rate for the film would keep everything in sync. The slow
motion on the set would translate back up to real-time rate. This would
look different than the previous example but the end result rate of the
piece would be the same: 8 bars at 110 bpm would be the same number of
video frames in each case.

(I have seen an effective piece where the singer is singing at the normal
rate of the song but the background is rushing by in a fast, time-lapse
manner. This huge rate of change probably requires a lip movement chart
like animation that is paced by a click track.)

If my previous assumption is incorrect, then you really want the sped up
(Monkee's 1968 music video?) look. What is "sync" in this case?


--- David Tosh  dlt at earthlink.net  (CIS 72167,1376)
--- Video Engineer, Complete Post, Hollywood


----- 
The telecine mailing list is automated with SmartList v.3.10.
It is available as a digest... questions to rob at xyzoom.alegria.com.