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DC120 Frames Per Second and Time Code
Transcript of DC120 Frames Per Second and Time Code
• Each field contains half of the horizontal lines that comprise a video image – one field contains all the even lines and one field contains all the odd lines.
• We refer to this as interlaced video.
• Television originally needed a
stable time reference.
• It had a convenient one with
the carrier frequency of electrical
current coming out of the
AC outlet – 60Hz.
- National Television System Committee
- They come up with the standards that
American broadcasters must adhere to.
- Society of Motion Picture and
also the name given to time code.
Frames Per Second and Time Code
• A system of drop-frame time code was adopted.
• It’s important to remember that no actual frames are
ever dropped – just the time code numbers.
• Drop-frame time code: To keep the time code and
wall clock in perfect synch, 2 time code frames are
dropped every minute except the 10th minute
(minutes: 00, 10, 20, 30, 40, 50).
• One of the results was that the frame rate was slowed
down by .1% which meant that the new frame rate was
• Because this new system slowed down frame rate,
it would no longer correlate to the actual clock on the
wall after a minute or so. An extra 18 frames are
accumulated per 10 minutes.
• With the advent of color television, engineers found a
way to keep the B&W transmission system intact.
• This meant that consumers were not forced to buy
new TV’s. The color information was sent along with
the old B&W signal.
• These fields clocked to each cycle of the carrier
– 60 cycles per second = 60 fields.
– 60 fields, in turn, equal 30 frames per second.
• Because the carrier frequency in Europe is 50Hz,
they have a frame rate of 25fps. (EBU – European
• It wasn’t until the advent of sound-on-film systems
in the late 1920’s that frame rate standardization was
• Playback pitch had to match that of the originals
• 24fps became the standard because it was fast enough
to do away with some of the “flicker” issues of lower
• Frames per second
• A frame is essentially an individual
If you put enough pictures together, fast enough, you get the appearance of motion.
One of the earliest forms of animated movement was the Zoetrope.