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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

24P or 23.98?

Record speed

Record speed

battistella said:
What frequency is RED recorded at. Will the 24P footage actually be 23.98 for use in NLE's or will we be working in true 24fps?
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Just to confirm, at "24p" its your choice 24.00 or 23.98 (a.k.a 23.976) fps. And 25.00 fps for Europe of course.
 
When digital finally gets its act together and becomes the norm, everyone can just relax...and shoot, and view, their productions at 25P. :)
 
David Mullen ASC said:
I shot one of the first F900 features, "Jackpot", and used the 24P setting, not the 23.98P setting (the camera allows both). The only problem I heard was that the editor ended up fixing some of the sync in the final mix session. Anyway, since then I've only shot HD in 23.98P and the sound post seems to work fine.
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If you would ever shoot 24 with the Red, where would you place the threshold where it would make more sense to shoot 24?
 
24P if your primary destination is to be film and/or theatrical distribution. Otherwise it's 23.98 or 25fps (PAL areas), or at least that would be my thinking.
 
I would be surprised if someone could tell the difference between an original 24.00 sound file and one pulled down to 23.98.

In PAL countries, can you not shoot 24.00 and do a frame for frame 25.00 fps transfer and then just adjust the audio (or vice versa for filmout)?
 
AngusChandler said:
I would be surprised if someone could tell the difference between an original 24.00 sound file and one pulled down to 23.98.

In PAL countries, can you not shoot 24.00 and do a frame for frame 25.00 fps transfer and then just adjust the audio (or vice versa for filmout)?
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Yes we speed up the sound 4% so it matches the image. The same for some 25 fps films that goes to theatre release. They speed it down 4% when printing the 35mm. Its a lot easier to work in 25fps since everyones workflow it built for 25. Only some posthouses can do real 24fps.
 
As David M. said, 23.976 or 24 can both go to a film-out with absolutely no difference in quality since a frame is a frame and recorded frame per frame back out. The same misunderstandings exist for ADAVNCED pulldown and NORMAL pulldown in the sense that you had to shoot ADVANCED to go to a filmout.

The issue is audio workflows - and how the prost process will be done. Sound post wants to do the least amount of sample rate conversion. Assume 48kHz as a recording format for whatever speed you want to shoot and master at - either 23.976 @ 48kHz or 24.000 @ 48kHz. Now depending on your post process and frame rate, there will either be a sample rate conversion or not - either in telecine or in the NLE itself if timeline does not equal acquisition rate.

The other factor in choosing frame rate on digital based cameras is whether or not it is being used as a second camera at the same time as a film camera - if the film camera us running 24fps, you want the digital camera to be the same - especially if shooting the same scene with audio. Or one of them will slip out of sync. The .1% is roughly 1 frame slip every ~1000 frames.

The following is a link to a chart that shows production frame rates, sample rates, project type rate for Media Composer - but the basics apply to all NLE and post processes.
http://www.24p.com/BWF_recording.htm


Related to the above - is that some studios have set a mandate that all post processes be done at 24.000fps and on set production for digital acquisition be 23.976 for picture and 47.952 kHz for audio. This allows for a 24.000 @ 48k Hz as mentioned above. The reason for this is for foreign deliverables and time to QC all audio elements - because of the sample rate conversion required if doing post at 23.976 @ 48kHz.

So, there will always be a sample rate conversion if delivering theatrical as well as HD and SD. The goal is to provide the least amount of sample rate conversion and maintain highest quality.

Michael
 
MichaelP said:
Related to the above - is that some studios have set a mandate that all post processes be done at 24.000fps and on set production for digital acquisition be 23.976 for picture and 47.952 kHz for audio. This allows for a 24.000 @ 48k Hz as mentioned above. The reason for this is for foreign deliverables and time to QC all audio elements - because of the sample rate conversion required if doing post at 23.976 @ 48kHz.
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Tell us which studio(s), because I have never heard of such a mandate at any one of them, and I deal with studio deliverables all the time.
 
Mike -

I don't know if I am at liberty to say, since most of these mandates have been done as internal memos. Three features over the last 6 months using Genesis, or other file based cameras have had the direct instructions to shoot 23.976 on camera and 47.952kHz on audio in order to keep a 24.000fps and 48kHz post production workflow. I have been involved in con calls with the VP's of post on every one of these calls.

In essence, this is no different than many of the feature films working in a "24p" project which has been the case since 1992 on Avid. But - with the 23.976 capture and NTSC based workflows, I prefer 23.976/48Khz for the entire post workflow until the final mix master for the theatrical deliverables.

But on the larger studio features with day and date release worldwide, the argument is that there is no time to QA all the sample rate conversions for all the stems needed for worldwide delivery and working at 24/48 eliminates 2-3 days from the schedule -

Michael
 
MichaelP said:
Mike -

I don't know if I am at liberty to say, since most of these mandates have been done as internal memos. Three features over the last 6 months using Genesis, or other file based cameras have had the direct instructions to shoot 23.976 on camera and 47.952kHz on audio in order to keep a 24.000fps and 48kHz post production workflow. I have been involved in con calls with the VP's of post on every one of these calls.

In essence, this is no different than many of the feature films working in a "24p" project which has been the case since 1992 on Avid. But - with the 23.976 capture and NTSC based workflows, I prefer 23.976/48Khz for the entire post workflow until the final mix master for the theatrical deliverables.

But on the larger studio features with day and date release worldwide, the argument is that there is no time to QA all the sample rate conversions for all the stems needed for worldwide delivery and working at 24/48 eliminates 2-3 days from the schedule -
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The real problem is that post sound is generally working at 29.97, not that the picture is captured at 23.98 or 24. You are, of course, correct that Avids have been using 24 frame projects for years, but quite frankly, that is quite unnecessary these days. The most common methodology I find for sound right now is to record production tracks using 48.048. This allows for a pulldown without sample rate conversion, useful both in telecine and for post sound.

There's only one studio I know of that gets this involved in technical issues, and my guess is that's the one your talking about. Hint: they're also the only one that has their own DI facility.
 
I agree that film based 24fps on set with 48.048 is the way post should go. That way a 23.976 process can be done throughout the post process- HD or NTSC as needed. Only one sample rate conversion at the end... but that is their issue due to schedule.

In this case, their production is 23,976fps, they just need to record at 48kHz to have the same workflow as above, but they want an on set 47.952 to have 24/48kHz in post.

As long as everyone is on the same page, it works.

Michael
 
Almost on topic. The 23.98 is really 24000.0/1001.0 and is traditionally used for 3:2 pulldown to convert 24 fps film to NTSC. As you would suspect the 29.97 stuff is really 30000.0/1001.0 again for NTSC originally.

Some useless information no doubt.
 
There's a good bet on that, Eric. Shooting at 23.976 vs 24.000 really makes no difference from the perspective of frames and frame rate. The difference is so small that either can be played back at the counterpart frame rate and no one will ever know. The issue is in synchronizing the audio with the frame rate.

I think most everyone (in NTSC land that is) will shoot 23.98 because primary distribution for most will be DVD / HD / broadcast, which is 59.97Hz -- 2.5x 23.98 and a match for 3:2 / pull-down. The only exception will be shooting 24.00 if primary distribution will be 24.00fps film-out or something of that nature. But in many situations, there will still need to be audio retiming at some point on a 24.00fps production as it will probably go out to DVD or other such media at some point.

Those in PAL regions have a little bit different choice to make... Do they shoot 24.00 for film out or 25fps to match with broadcast and DVD / HD video standards?
 
Eric Edwards said:
If intentions were to do a film-out as well as a DVD release, etc, what would be the more ideal situation?
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You pick. In that situation, you will be re-timing the audio for one release or the other -- you shoot 23.98, you'll have to re-time for the film out, or re-time for DVD release if you shoot 24.00.

I think in that situation, you pick based on your post workflow and/or your studio setup. Talk to your sound crew / guy / (inner sound guy), depending on the situation and see what works for them too. If you'll be recording sound to the RED One, then does all this even matter provided your editing and other post software can deal with the rates chosen and make the necessary adaptations.
 
Jeff Kilgroe said:
You pick. In that situation, you will be re-timing the audio for one release or the other -- you shoot 23.98, you'll have to re-time for the film out, or re-time for DVD release if you shoot 24.00.
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That is not the case for picture. There is no retiming for a film out. A frame is a frame, regardless of how fast the sequence of frames is running. A sequence of frames being recorded to film has no frame rate, only PC and Mac based movie files do. If you're working in the US, there is no reason to shoot 24 fps at any time. Not that you can't, but there simply isn't any reason to. Most post production today is based on broadcast video standards. During post production, one almost always has to deliver screening copies on some video format - DVD, HD videotape, whatever. It's much easier to do this if you stick to a "video friendly" frame rate, like 23.98, especially when there is no real downside to doing it. Not to mention that almost all sound post facilities work in 29.97 - and yes, that does mean there is a pull up needed for the optical tracks, but that is a reasonably simple step that is done by just about every sound facility.
 
mmost said:
That is not the case for picture. There is no retiming for a film out.
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Re-read my last couple posts... I'm talking about re-timing the audio to match either a 23.98 or 24.00 frame rate as necessary. I already stated that the actual frames make no difference.

mmost said:
A frame is a frame, regardless of how fast the sequence of frames is running. A sequence of frames being recorded to film has no frame rate, only PC and Mac based movie files do.
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I'm not sure what you're trying to say here. While it's true that a frame is a frame and you can play a sequence back at any rate you choose, that doesn't mean a sequence doesn't have a framerate. Frame rates aren't limited to or necessarily defined by movie files on whatever computing platform you deal with them. You hand someone a 35mm film reel, they're going to assume it's a 24.00fps sequence of images unless you tell them otherwise.

mmost said:
If you're working in the US, there is no reason to shoot 24 fps at any time.
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Yes you would, if your post process is based on a 24.00fps pipeline for film and you will be cutting RED footage (image frames and audio) with 24.00fps material shot on film.

We haven't touched on it really here, but Blu-Ray and HD-DVD both support 23.976 *AND* 24.00 and many new HDTV sets accept 24.00 input via HDMI. Upcoming 120Hz displays can time true 24.00 too. So to say there is no reason to shoot 24.00 is pretty short-sighted. But if you're shooting something that will see 99% of of its distribution on DVD or common broadcast systems, then yes, 23.98 is the most logical choice. But I think I already said that most everyone will be shooting 23.98...

mmost said:
During post production, one almost always has to deliver screening copies on some video format - DVD, HD videotape, whatever. It's much easier to do this if you stick to a "video friendly" frame rate, like 23.98, especially when there is no real downside to doing it.
Click to expand...

Lots of different ways to look at this here. It's still possible to work in a 24.00fps post workflow and deliver 2:3:3:2 pull up to 59.97 for NTSC delivery for rushes / dailys, whatever.

We're really making mountains out of mole-hills with this discussion in here. In today's post world, this is all no big deal. Most common NLE software will re-time audio if needed when you output from a 24.00 editing space to a 23.98 delivery or vice versa. The real issue is making sure that all people in the production pipeline are paying attention and are on the same page. The 24.00 vs 23.98 problem is largely an audio issue. And as you pointed out, many audio facilities work at 29.97, and often do regardless of whether their editing for a 24.00 film flow or if it's NTSC broadcast. As long as their target delivery format is understood, it's not an issue. Coming from the world of film production, most people assume "24fps" means 24.00fps. Coming from the world of video, broadcast and HD production, "24fps" has largely meant 23.98, but as was said earlier in this thread, the labeling has become better with newer cameras that support both 24.00 and 23.98.

So yeah, 23.98 is the way to go... Unless you need 24.00. And if you think you need 24.00, chances are you probably don't or it still makes more sense to go 23.98 in the long run. But many Hollywood productions still like to conform to 24.00 all the way through post and initial film delivery. They conform to 23.98 (and/or 25fps PAL) when it comes time to create the DVD release.
 
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