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Why still use 23.976 and 29.97?
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You could load the quicktime into Apple Cinema Tools and use the “conform clip” function to change the QT header to 29.97 that is an instant change.
-Rob-
Robert Houllahan
Director / Colorist
Cinelab Inc.
http://www.cinelab.comMAHC-PRO 6-Core 3X GTX285 20Tb SAS Wave Panel Panny 11UK SDI Plasma.
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[Joseph Mastantuono] “30p though should be easy to covert to 2997 in compressor”
I realized this was on question I had not asked.
Is there any “damage” done when converting 30fps to 29.97? Or 29.97 to 30.00?
I did some tests and I could not see or hear any difference. I don’t have enough experience to know if there may be any problems here though.
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As long as you use the “source plays frames at 2997” option there will be no damage, as its not changing any frames, just telling it to play them at a different frame rate.
Joseph Mastantuono
http://www.goodpost.net
Color Grading & Post Production Consulting -
Consider external audio sync issues if you are in fact converting from “whole frame” 30.000 fps to 29.97.
I know this from long and hard-won lessons transferring 24 fps film (the kind with sprockets) to 2997 with double system sound. In fact it is this frame rate that is the “pull down” that people refer to as “3:2 pulldown”. (Its not the “pulldown” that gets removed, its the redundant fields).
Also beware that some consumer solutions obfuscate the frame rate nomenclature in a vain and misguided attempt to simplify things for an otherwise oblivious market. For example, Final Cut still refers to 23.98 as “24”. It makes it confusing for those of us who actually understand these things, and need to know what the exact frame rate is. So although you may indeed be shooting at 30.000 fps, there is still the possibility that that is in name only, and would be a mightily weird choice and a departure from over a half a century of an established format. It does disqualify your project from a majority of transmission methods.
jPo
You mean “Old Ben”? Ben Kenobi?
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The 23.976 and 29.97 scanning frequencies are mathmatically compatible with the original 59.94 scanning frequency of the NTSC color system. The 59.94 frequency was a modification of the original black and white TV system in the US which scanned at 60hz in sync with the AC power frequency. The modification to 59.94 Hz was necessary to maintain backward compatibility with the older B&W tv sets with regard to the audio signal. The new 3.58 mHz color subcarrier had to jibe mathmatically with the number of total scan lines per second (525×30) and in order to do so and still jibe with the original audio subcarrier (4.5 mHz), a small reduction (.1%) had to be made, hence 59.94. We are still conforming frame rates and scanning frequencies to a 60 year old analog engineering compromise. Go figure.
In this regard, 23.976 is the universal master frequency as it conforms mathematically to all the other standards, with certain pulldowns applied where needed.
dm
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[Dean Manion] ” 3.58 mHz color subcarrier had to jibe mathmatically with the number of total scan lines per second “
Also has to be a multiple of the horizontal scanning frequency (15.75 KHz) to come out to colour-framed subcarrier phase on odd/even fields. This is compounded slightly by the existence of half-lines in analog NTSC. An active NTSC field is 262.5 lines, so each one starts 90 degrees out of phase with the preceding field. This used to be very important in composite baseband editing, but the advent of component processing (Betacam) changed the parameters. Its why there is a 2F/4F switch on the front panel of those decks that were also expected to function in the analog NTSC baseband world.
The 15.75 KHz scan is the source of the high-pitched squeal that CRTs used to produce as a result of the flyback transformer that generated the sawtooth voltage that sprayed the beam across the faceplate.
jPo
You mean “Old Ben”? Ben Kenobi?
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