Shooting and editing at 24P, not 23.98

Question

I am based in Beijing, where video is PAL. I’m working on pre-production on a feature film to be shot on a Varicam and edited in Final Cut Pro. We want to base editing around a future film print, and would rather shoot and edit at true 24p and not 23.98. We do not want to do an offline edit. I have one small question and one big question:
1. Is 23.98 merely to facilitate an easy NTSC workflow? I understand there are also sound-sync issues involved (?). We will be recording onto tape and DAT simultaneously.
2. I’m trying to create a “true” 24p FCP setup, so there will be no 23.98 element. I’ve installed the DVCproHD Components 1.1 and Frame Rate Converter for Final Cut Pro. Below, I’ll refer to true 24p (not 23.98) as “24.0”.
I’ve read this both can be done and cannot be done, and our team has discovered a maze of detailed pieces of disinformation regarding DVCPRO HD and 24p. Most articles and posts say FCP cannot do 24.0, but the Frame Rate Converter documentation seems to suggest this is possible.
I have created a 24.0 Easy Setup with:
- Sequence Preset with a 24.0 editing timebase; timecode rate “same as editing timebase”; Quicktime compression type 720p60 with 24.0 fps.
- Capture Preset with 720p24, and capturing at 23.98. (This appears to be unchangeable, and the compressor settings are locked at 59.94 fps. So it appears while the Varicam can shoot 24.0 progressive [with duplicate frames], FCP can only capture 23.98.)
- Device Control Presets with DVCPRO HD firewire preset I modified to a frame rate of 24.0.
So, I think I have all the setting set up for 24.0 EXCEPT for the compressor setting inside the capture preset, which appears to be locked at 59.94 and capturing at 23.98. So it looks like the only block to editing 24.0 DVCPRO HD is that FCP can’t capture it.
We are for sure going to use Varicam and edit on FCP 5.0, and if there’s no way to really edit online 24.0 HD, then we’ll do 23.98.
Thank you for any help. And as there are many conflicting posts and documentation on this issue, it would probably be most helpful for those with first-hand experience editing 24.0 in FCP to reply…
Quad G5 Power PC, G4 Powerbook Mac OS X (10.4.7)

Answer 1

Great question and the best of it all, you will have a true 24fps and 48k audio project throughout! Your settings look good.
It actually took me some time to figure out where you even seeing the 23.98 but I did find it under sequence presets. Mmmm... Now to explain this in a short e-mail.
1. The problem is all with NTSC. If you stay in FCP, output to HD, never look at the video on an NTSC monitor, then your project will always be 24fps and the audio will always be 48k. No worries. As a result, that 23.98fps frame rate in the Summary Sequence setting is a bit misleading and only applies to playing back 24 frame projects on NTSC equipment - laying back to tape and viewing on a NTSC TV/Monitor. (This is true for film based or HD projects - film runs at 24fps too). In FCP, Your sequence willsonly playback and edit 24fps.
2. Why is 23.98 even there then? The answer takes 3 steps - do you have the patience to read them all, as it is quite dry.
STEP 1: (what most people know)
NTSC puts 29.97 frames a second on a screen. Your version of reality was recorded at 24 frames a second. If we could just bypass all the electronics built into your 24HD deck and NTSC monitor and just play your tape on a NTSC monitor, your images would look like everyone is moving about 25% faster (29.97 divided 24). Another way to look at this is that in 10 seconds, the NTSC monitor will display 299.7 frames (10 seconds times 29.97). If we played back 299.7 of your frames in 10 seconds, we would actually be looking at about 12 seconds of your recordered reality. So the important how do we keep your 24fps looking like reality rather than speeding it up? The answer is to add 5.97 frames to your image when playing back on a machine that is displaying 29.97fps (NTSC). Believe it or not, this is not that hard to do. The most basic explanation being that by duplicating some of the 24fps frames and merging others you create an extra 5.97 frames and simply insert these extra frames inside the 24 so that you now have 29.97 frames instead of 24. Done properly, your eye cannot see the difference.
Step 2: (what confuses the people not already confused from above)
The problem arises is what the heck is .97 of a frame? What does it look like? It doesn't. Only 1 full frames are added. This is really an accounting problem, like where do all the quarter of a pennies go in the world? (Only Richard Pryor from Superman and the guys from Office Space seem to know.) The answer is, since we are already tricking your eye by adding extra frames that never existed in the first place on film (24fps) or 24 HD, by just not adding one of these 'created' frames every 10 seconds or so (you will never miss it don't worry) when you do the accounting in the end, an odd number like .97 of a frame is created. Bottom line - 6 full frames are added per second (24 real frames+6 created frames= 30 frames - darn close to 29.97), then by not adding one frame occasionally drops the overall average to 29.97) making TV networks happy, engineers look like geniuses and the rest of us posting long dry explanations on the net.
STEP 3 (The step almost no one understands, not even completely by me)
Ok, if you gotten this far and have an understanding congrats! So although the entire explanation above was a mathematical one, it was all really about our experience of ‘seeing.’ Everybody sees reality occur at the same pace (yes sport superstars seem to see things slower than others) but as humans we basically all see reality at about the same pace. The explanation above dealt with a technical issue that when reality is recorded at one speed and played back at another, how do we balance those technical things out so that people viewing the material see it as it was meant. Ok, here is the kicker - what about sound? Mmm, didn't think about that did you? I mean CD's have a frame rate of 44,000 samples a second called 44k. HD, DVcam, DAT all have 48k or 48000 samples a second – think of it like frames a second). So what do you do when all your material is in sync in your FCP (or Avid) playing back nicely at 24fps and you want to make an NTSC tape or watch it on a big TV monitor? Well if you are lazy like me, you would just duplicate 25% of the sound just like the picture (30 divided by 24) and just add it in at the same time you add in those extra 6 frames!! Perfect. But of course you cannot. Well actually you can, but it would sound bad, clicking and hiccupping. Your experience of the sound would be odd. So the engineers had to come up with another way to deal with sound. The slowed it down!! That’s right, since you can't add extra sound like picture, when converting 24 frames to 30 frames, they slowed the sound down. I am not an expert in this field so I dare not explain it as I am sure to create some inaccuracies, but that is what they do. So when you are listening to an Avid or FCP through an NTSC monitor or outputting to tape, the audio is being played back a little slower (47.97 in a 48k project) then how it was originally recorded! Again, engineers are tricking you – your ear this time. This minute slow down of the audio is not perceivable to most people.
ENOUGH!! SO WHAT ABOUT 23.98?
Ok ready? Digital Audio is the issue here. Digital Audio, DAT, DVcam, HD, DA88, is mostly recorded at 48k. CD's are 44K, but most other formats are 48k. The 24fps conversion to 29.997 conversion causes a major headache for audio folks. Without more boring details, when converting video from 24fps to 29.97fps, all the people have to re-adjust all of their audio from 48 to 49.97 to keep in sync. As a result they spend a lot of time converting their audio and more importantly to them, they lose the pure digital clarity. Also handing sound files back and forth between picture editors and sound editors and music editors has never been convenient because of this issue. At some point a sound file is imported or exported incorrectly and the sound has to be put through a digital process to get it to be in sync again. So how do you solve this constant tedious conversation about whether the Audio is at 48k or 49.97? Well the problem becomes an accounting one once again. The issue really is how the video editing machines account for time code. For the longest time, these machines were built with the idea "We do 24fps everybody resample around us." Remember, this technology was invented only 15 years ago when disk drives were small, machines were slow, and moving pictures were severely compressed to just to get them onto the hard drives. Keeping everything in sync was a major hardware task back then, and sales of machines that could edit 24 frames were dominated by film companies who only knew about 24 frames a second. Now, not so much. So to keep the audio at 48k and not need any conversions, the video editing machine would have to account for the conversion between 24fps and 29.97 NTSC time code slightly differently. The answer is to play back 24fps back at 23.98 to NTSC devices and as result the audio would stay pure and original at 48K!! However, your cackles would arise and of course would cause the question in everyone’s mind which was your first question “are we really editing at 24fps?” Which is of course why long ago nobody ever marketed a 23.98 Video Editing Software/hardware solution because all day long they would have to answer this question over and over. Better just make the machine do everything at 24fps (even the accounting) and let the audio grunts have to deal with it.
So the answer is yes, you will be editing in 24fps. Audio will remain at a pure and original 48k. And if you have to output to NTSC for any reason (and yes I promise you one will come up) the machine will play the picture back at 23.98 so that it looks great and the audio will come out at a pure 48k.
Good luck
Doug