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Old February 17th, 2009, 09:02 AM   #1
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Field recorder frame rates other than drop-frame

can someone explain why 30 FPS and 29.97 NON-drop frame are still available? Are we talking about film vs video?
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Old February 17th, 2009, 12:17 PM   #2
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David,
I think the reason 29.97 Non-drop is still available is a lot of video streams are still running at at that speed and the timecode is often Non-drop so it would match up easily. If you are shooting 24P it is often recorded in a 60i or 29.97 stream. As for whether this is film versus video the answer is yes that has something to do with it although it can just as well be video vs video these days.
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Old February 17th, 2009, 01:52 PM   #3
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Drop frame is actually a mastering code where it's important for the timeline to match closely to actual clock running time. Also used a lot in ENG applications and short form shooting such as commercials. But for long form productions, a lot of the camera original is still recorded with non-drop timecode as it can be simpler when matching to audio without the missing numbers.
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Old February 17th, 2009, 02:34 PM   #4
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thx for the replys gents.
Steve, any theories on why 30 FPS is still around?
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Old February 17th, 2009, 05:49 PM   #5
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We used to use 30fps to lock multiple analog audio recorders together many years ago when I worked in music recording. Easier to calculate. A hold-over maybe for audio-only work?
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Old February 17th, 2009, 06:16 PM   #6
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Originally Posted by David Morgan View Post
thx for the replys gents.
Steve, any theories on why 30 FPS is still around?
Audio for film and some Hi-Def 24p video may be recorded at 30FPS; it all depends on the post-production workflow. Remember that audio doesn't actually have "frames" at all - audio is audio regardless of any "FPS" setting and its speed is determined by the sample clock rate, timecode settings have absolutely nothing to do with it. The whole purpose of the exercise is to make it easy to identify the snippet of audio that was recorded at the same time a given film or video frame was recorded and in file-based workflows that's all it does. Audio with 30 FPS timecode and a smartslate slaved to it shot by the camera at the start of a take establishes an absolute sync point regardless of whether the camera is shooting film, NTSC video. PAL video, hi-def, 24p or whatever.
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Old February 17th, 2009, 06:29 PM   #7
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Old February 19th, 2009, 10:52 PM   #8
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actually its a bit more complicated...

first all NTSC is 29.97 FPS of video. SMPTE doesn't define fractional frame rates, yet some vendors have implemented it :( TC should be 30.000. under these circumstances, 30.000 FPS is labeled 29.97 NDF, and runs out of sync against the wall clock by 7.5 secs per hour. 29.97 TC = 30 FPS DF TC

however, film cameras and a select few video cameras can run at 30.000 FPS where 30FPS images = 30 FPS TC exactly

for 23.976 FPS video, which is most "24"fps video, 29.97 non drop is always used because getting into drop frame becomes extremely messy to compensate out phantom video frames vs dropped TC frames. its just way simpler to use NDF.

OTH **some** cameras can shoot 24.000 FPS video such as the F900. in that case you can ( should ) use 24FPS TC or 29.97 NDF = 30.00 FPS TC. either will work.

if you aren't done having fun yet, 720P video always puts down 59.94 frames to tape, but when shooting at lower frame rates simply adds duplicate frames in to pad it back out. 60.000 is also a valid 720P frame rate, but I think pretty rare to ever deal with.

worse is that at least with JVC, the have 24FPS TC when shooting 24, but some NLE's like FCP read it as 29.97 NDF by using a kulge of adding frames from the 24.00 to create 29.97 along the lines of : frame 13 becomes 14, 14 becomes 16, 15 becomes 17 or 18. of course when the shuttle the deck single frames, they don't apply the same funky offset math and the deck can't find frames about 23 because they of course don't exist on tape, but do in FCP's screwy world.

the real problem is because 30 can often ( normally does ) refer to 29.97, you can
t always be sure this ages old reference is always being used the same way because there are some products that implement 30.000 and the fractional 29.97.... even though SMPTE says is shouldn't exist. I love standards, which one ? :(
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Old February 20th, 2009, 04:19 AM   #9
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