User manual

495
Synchronization
• VITC (Vertical Interval Timecode) is contained within a compos-
ite video signal. It is recorded onto video tape and is physically
tied to each video frame.
• MTC (MIDI Timecode) is identical to LTC except that it is a
digital signal transmitted via MIDI.
Timecode standards
Timecode has several standards. The subject of the various
timecode formats can be very confusing due to the use and
misuse of the shorthand names for specific timecode stan-
dards and frame rates. The reasons for this confusion are
described in detail below. The timecode format can be di
-
vided into two variables: frame count and frame rate.
Frame count (frames per second)
The frame count of timecode defines the standard with
which it is labeled. There are four timecode standards:
• 24 fps Film (F)
This frame count is the traditional count for film. It is also used for HD video
formats and commonly referred to as “24
p”. However, with HD video, the
actual frame rate or speed of the video sync reference is slower, 23.976
frames per second, so timecode does not reflect the actual realtime on the
clock for 24p HD video.
• 25 fps PAL (P)
This is the broadcast video standard frame count for European (and other
PAL countries) television broadcast.
• 30 fps non-drop SMPTE (N)
This is the frame count of NTSC broadcast video. However, the actual
frame rate or speed of the video format runs at 29.97
fps. This timecode
clock does not run in realtime. It is slightly slower by 0.1
%.
• 30 fps drop-frame SMPTE (D)
The 30 fps drop-frame count is an adaptation that allows a timecode dis-
play running at 29.97 fps to actually show the clock-on-the-wall-time of
the timeline by “dropping” or skipping specific frame numbers in order to
“catch the clock up” to realtime.
Confused? Just remember to keep the timecode standard
(or frame count) and frame rate (or speed) separate.
Frame rate (speed)
Regardless of the frame counting system, the actual
speed at which frames of video go by in realtime is the
true frame rate.
In Cubase the following frame rates are available:
• 23.9 fps (Cubase only)
This frame rate is used for film that is being transferred to NTSC video
and must be slowed down for a 2-3 pull-down telecine transfer. It is also
used for the type of HD video referred to as “24
p”.
• 24 fps
This is the true speed of standard film cameras.
• 24.9 fps (Cubase only)
This frame rate is commonly used to facilitate transfers between PAL and
NTSC video and film sources. It is mostly used to correct for some error.
• 25 fps
This is the frame rate of PAL video.
• 29.97 fps
This is the frame rate of NTSC video. The count can be either non-drop
or drop-frame.
• 30 fps
This frame rate is not a video standard anymore but has been commonly
used in music recording. Many years ago it was the black and white
NTSC broadcast standard. It is equal to NTSC video being pulled up to
film speed after a 2-3 telecine transfer.
• 59.98 fps (Cubase only)
This rate is also referred to as “60 p”. Many professional HD cameras re-
cord at 59.98 fps. While 60 fps could theoretically exist as a frame rate,
no current HD video camera records at a full 60
fps as a standard rate.
Frame count vs. frame rate
Part of the confusion in timecode stems from the use of
“frames per second” in both the timecode standard and
the actual frame rate. When used to describe a timecode
standard, frames per second defines how many frames of
timecode are counted before one second on the counter
increments. When describing frame rates, frames per sec
-
ond define how many frames are played back during the
span of one second of realtime. In other words: Regard-
less of how many frames of video there are per second of
timecode (frame count), those frames can be moving at
different rates depending on the speed (frame rate) of the
video format. For example, NTSC timecode (SMPTE) has
a frame count of 30
fps. However, NTSC video runs at a
rate of 29.97
fps. So the NTSC timecode standard known
as SMPTE is a 30
fps standard that runs at 29.97 realtime.