Jump to content


Photo

Film scanning at 24fps or 25fps?

film scanning frame rate 24fps 25fps

  • Please log in to reply
5 replies to this topic

#1 Christian Schonberger

Christian Schonberger
  • Basic Members
  • PipPipPip
  • 155 posts
  • Sound Department
  • Lisbon

Posted 17 November 2016 - 03:18 PM

Hello group,

 

Working on a short film, shot on Super 16mm. Well I just have a humble converted K-3, so the frame rate is not exactly 'accurate'. Sound will all be added in post. But I wonder why all labs here in Europe have a default film scanning frame rate of 25 fps and in the US it is 24 fps. Especially since all cameras I know of meant for screening (as opposed to European TV) always have a frame rate of 24fps, including the old Super 8mm sound cameras. 

 

I know that 25fps comes from the old PAL television standard (50 fields per second, 25 frames - all movies shot at 24 fps ran slightly faster to be in sync with the TV standard). 

I would like to choose a frame rate which is the most compatible with HD 1080p. No planning on getting my humble movie projected theatrically, but I would like to have it as compatible as possible with existing (and if possible future) standards. Also: if I work at 25fps and it will be played back at 24fps or vice-versa (not sure about the digital tech details though), the sound will be altered. At the very least its speed and probably also the pitch, as was the case back in the analog days - which is bad especially for music. Any tune recorded at 24fps and played back at 25fps is almost a half step higher and the tempo is faster (I am a pro musician and I checked it many times). I would love to work at 24fps, simply because it's the cinema standard. My main concerns are compatibility and sound. The look of 24fps vs 25fps is virtually indistinguishable (IMHO) on modern screens and monitors. 

 

Any input, insight and tips highly appreciated. 

 

Thanks in advance,

Christian


  • 0




#2 David Mullen ASC

David Mullen ASC
  • Sustaining Members
  • 18987 posts
  • Cinematographer
  • Los Angeles

Posted 17 November 2016 - 09:10 PM

Technically a scan has no frame rate, it's a scan of each individual film frame -- it's up to you as to the speed you want to play back the frames.

 

Frame rates come more into the picture, so to speak, if you are doing a telecine transfer to a video format.

 

But even in Europe, you should be able to get a scan or a telecine transfer to a non-broadcast format, let's say, 2K ProRes in whatever aspect ratio you want, and at 24P if you want.

 

If you plan on just watching the footage on your computer, then a 24P file will play fine, and even a DVD or blu-ray player can show 24P material on a TV set, converting it to the display rate of the monitor. But for anything handed over for broadcast, you'd have to convert the file to either a 50Hz or 60Hz standard.

 

I think you will find that at some point, your 24P project might get shown at 25 fps in Europe somewhere... but not being European, I'm guessing a bit here, you'd get a better answer from someone in PAL-land.


  • 1

#3 aapo lettinen

aapo lettinen
  • Basic Members
  • PipPipPipPip
  • 774 posts
  • Other
  • Finland

Posted 18 November 2016 - 07:50 AM

the scanning fps does not matter if you are not transferring sound from the film at the same time. 

 

The 24/25fps or 25/24fps speed change is a simple metadata change or clicking a button in edit, takes two seconds. As long as the film frames are transferred 1:1 to video frames (no telecine conversion) it does not matter at all. 

 

Here in Finland movies are shot for theatrical release at 24.00fps and for television at 25.00fps always. It it's a TV movie (normally in these cases, a documentary feature) which is later decided to also be released theatrically it is usually shot and edited + post made at 25fps and then the final image conformed to 24.00fps for DCP and separate audio mix done for 24.00fps dcp.  

 

In some countries, I have heard, it is quite normal to shoot at 25fps even when shooting mainly for cinema release. One of the reasons we always shoot 24fps in camera for cinema release here may be that we are so used to convert all the foreign movies from 24 to 25 with audio speed change that it is just practical to use the same workflow also with our own movies. 

 

I recommend just scanning at whichever framerate is easier and more economical and just conforming the playback rate in edit to whichever was the rate in camera. then syncing the audio and editing normally. If you are doing separate 24fps (bluray, web, DCP) and 25fps (TV, dvd) releases you will make the version after the editing and image post is done, just remember to ask for both the 24fps and 25fps soundtrack masters (they are different lenght and there is some work involved when doing the speed change but for image it is just a simple click of a button with zero quality loss when swithing between 24 and 25)


  • 1

#4 aapo lettinen

aapo lettinen
  • Basic Members
  • PipPipPipPip
  • 774 posts
  • Other
  • Finland

Posted 18 November 2016 - 07:59 AM

for bluray and DCP: 24.00fps  

for DVD and broadcast: 25.00fps 

for exporting to NTSC countries: 24.00fps (and they can convert it later to 29.976 if absolutely necessary)

 

always do the framerate changes to image by conforming so that all the frames are 1:1 and the program lenght in seconds will change, then change the audio speed to match the different program lenght. 

Ghosting and double frames are much more apparent in the final product than couple of % audio speed change (most people don't notice it at all when the audio pitch change is compensated at the same time) so this is the best way to do the conversion quality-wise.


Edited by aapo lettinen, 18 November 2016 - 08:05 AM.

  • 1

#5 Perry Paolantonio

Perry Paolantonio
  • Basic Members
  • PipPipPipPip
  • 380 posts
  • Other
  • Boston, MA

Posted 18 November 2016 - 08:14 AM

If you're planning to make NTSC DVDs, or broadcast in the US, 23.976, not 24. That way you can easily encapsulate it into an NTSC (29.97i) or 1080i signal. 

 

23.976 will also play back natively on Blu-ray in non-NTSC countries.


  • 1

#6 Christian Schonberger

Christian Schonberger
  • Basic Members
  • PipPipPip
  • 155 posts
  • Sound Department
  • Lisbon

Posted 18 November 2016 - 08:31 AM

Thanks for all the very useful information. 

Yes: the audio change in pitch is much less distracting (if noticeable at all to viewers) than those nasty "dissolving double frames", old school NTSC 3:2 pull down and repeated frames. I love seeing film being shown each frame in full and for the exact same duration (like old school film projection). No jerky motion. This is the max priority, not the exact frame rate itself by a rather narrow margin (as long as the audio remains 100% in sync). 

 

I will choose what ever is the most affordable, produce the audio in perfect sync and take it from there.

 

Thanks a lot again - this was very helpful.

 

Christian


Edited by Christian Schonberger, 18 November 2016 - 08:33 AM.

  • 0



Also tagged with one or more of these keywords: film scanning, frame rate, 24fps, 25fps

Pro 8mm

The Slider

Tai Audio

Glidecam

rebotnix Technologies

Visual Products

CineLab

Willys Widgets

Abel Cine

Quantum Music Works

Metropolis Post

Broadcast Solutions Inc

Zylight

FJS International, LLC

Rig Wheels Passport

Paralinx LLC

Ritter Battery

Aerial Filmworks

Technodolly

CineTape

Ritter Battery

Pro 8mm

Willys Widgets

Abel Cine

Metropolis Post

Aerial Filmworks

Tai Audio

Technodolly

CineLab

Broadcast Solutions Inc

Rig Wheels Passport

rebotnix Technologies

Visual Products

The Slider

Glidecam

CineTape

Paralinx LLC

Zylight

FJS International, LLC

Quantum Music Works