ACN-TL
Rev. 6.00
©2019, Ambient Recording GmbH
24
There is no double rate
What continuously leads to confusion is the fact, that there are no TC framerates that match 47.94, 48,
50, 59.94 or 60 video rates. This lies in the historic and physical nature of the SMPTE TC signal which
doesn’t allow
for higher frame rates than 30 FPS. To simplify configuration, Lockits since firmware 6.00
allow selecting double rates. This doesn’t change the fact, though, that on those settings the timecode
frame rate always will be the corresponding single rate.
2 worlds with 2 frame rates each
Basically the video world is split in 2: PAL and NTSC.
PAL uses 24 FPS TC for film and 25 for video/TV, NTSC productions take place in 23.976 for scene based
work and also TV and 29.97 for broadcast/sports.
23.976 mostly is also referred to as 23.98 and sometimes even reduced to 23 in writing. No matter how,
it’s all the same, there is no other “23” format than this one and as of today it is THE format for scripted
productions you will find yourself working with most of the time when you live in the NTSC part of the
world.
29.97 again may use 29.97
“
Drop
”
(also “D” or “DF”)
in some cases. Without going down to the nasty bits
of this pesky format it is enough to know that 29.97 Drop is the ONLY drop format that exists and it is
only consistent within itself. So, if asked to use Drop, make sure EVERYTHING is set to that, which can
be a challenge, as RED DSMCs do not even support this.
The last frame rate, 30 FPS have become more or less obsolete in the meantime except some industrial
cameras.
One Frame Base across the Set
Terms like system rate may also apply. This is not only the frame rate the camera is internally working
at but also post production and editing will be performed at.
There are negligible few cases that you really would need to cross sync a camera to an audio recorder
using a different TC frame rate. If you have to handle such situations, you will know your stuff, if not
just set everything to run on the same frame base.
•
In any case, do NEVER mix and match DROP with NON DROP or NTSC area with PAL area
rates!
The Camera is Always Right
Whatever the frame base is going to be, you will never succeed in trying to sync to a camera to a signal
that does not match its requirements. So, in general, the Lockit just needs to be set at the cameras
system/project rate. This may become tricky as e.g. some Sony cameras will effectively operate on
23.976 when set to 24, some Panasonics on 29.97 when set to 23.976. So, it is important to know your
camera system rate and sync format.
