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Cinema Físico
Cinema Físico
Inspiring
July 21, 2020
Question

Footage is in slow motion but shows 23,976

  • July 21, 2020
  • 4 replies
  • 3331 views

Hello, 

 

Receive footage from Alexa and Red and the frame rate shows 23,976. It is in slow motion, but "how"slow is it? Where can I see the exactly frame rate the footage was shoot? And what is the name for this process the camera shoot in slow motion and it shows the footage is 23,976. Why DPs or DITs make the the frame rate shows 23,976? Am I missing something?

 

Take care,

This topic has been closed for replies.

4 replies

S
salvo34
Inspiring
July 22, 2020

I'm a little embarassed to share this, but what the heck. It's pretty terrible cause I didn't light it correctly.

But this is what 120fps is supposed to look like in terms of speed... 

15 seconds...roughcut ( just screwing around in apt. during virus stuff ).

 

https://vimeo.com/440500181

 

 

    S
    salvo34
    Inspiring
    July 22, 2020

    Ferando, I'm sorry but I have no clue why your stuff is like that.

    In general my observation has been that pro equipment and prosumer stuff is vastly different. To make matters more confusing, each manufacturer is doing stuff they decide on their own, thinking it's clever.

     

    My bmpcc 4k has option to shoot 120fps ( for example ). For some unknown reason the display ( when 120fps is chosen ) looks like this image I just made for you.  Notice it says 120fps / 23.98.

    I have absolutely no clue why it says that. I put the 120 stuff into an 23.976 timeline and expect it to be slow motion (23.98 rounded off 'playback' ).

     

    The camera is showing that the 120fps is supposed to be put into a 23.98 timeline ???  I have no idea.

     

    Good luck !

     

      M
      mh2010
      Participant
      February 8, 2022

      Just happened on this browsing for an answer on a related question, thought I'd answer in case anyone needs the info later.

       

      The camera is showing that the 120fps is supposed to be put into a 23.98 timeline ???  I have no idea.

       

      Yes, you're correct. Slow motion settings in camera are usually a combination of two settings: your shooting frame rate (120 fps in your example) and a time base (23.98 in your example). Many cameras just don't show it explicitly like this-- it'll just assume you want the time base as whatever your camera was recording in before that.

       

      Specifying the time base is just metadata-- a convenience to make sure that the correct speed of slow motion carries through to the editing software and matches the time base of your other footage. You might have shot 48 fps on a 24 fps time base, because the director wanted half-speed slo-mo. However, there's no reason the editor couldn't later change it to a 30 fps time base, in which case it would play back as less slow.

       

      The only other technical thing to note is the metadata OP Fernando got: 47 fps on a 23.976 timeline. They might have actually shot 47 fps for some reason (we think of 48 fps being more standard). However, twice 23.976 is actually more like 47.95 fps, so it may just be that it displays shooting frame rate without the decimal places.

       

      Graeme Bull
      Community Expert
      Graeme BullCommunity Expert
      Community Expert
      July 22, 2020

      Premiere sees it as that, it's  not uncommon to have to interpret the footage after import when Premiere gets it wrong. Metadata is either incorrect, or the camera shoots at that double frame rate and then elongates the clip in the encode process. Just guessing, but either way, getting the info from DP and then interpreting footage is best. Your other question is best left for the person using the camera I think.

        S
        salvo34
        Inspiring
        July 21, 2020

        I think you can ask whoever gave you the stuff from alexa and red and all the other cameras they used, by asking them what fps they shot it at... or.... else maybe use mediainfo or something like that ... 

        The cameras give metadata re: what is shot in them... not the DP or DIT or other magic people.

         

         

          Cinema Físico
          Cinema FísicoAuthor
          Inspiring
          July 22, 2020

          Salvo 34,

           

          Look at the Metadata and found that :

           

          Project Time Base is 23, 976 fps

          Record Frame Rate is 47 fps

           

          Why DPs choose this setup?

           

          Thanks

          Fernando AlvesEditor
          M
          mh2010
          Participant
          February 8, 2022

          The DP (or director who instructed the DP) wanted half speed slow motion. So they set the time base (the rate at which the footage plays back) to 23.976 fps, and they shot at twice that (47 fps record frame rate). 

           

          We think of 48 fps as being more standard as a slo-mo shooting frame rate, since it's twice the traditional film frame rate of 24 fps. However, twice 23.976 is actually not quite 48 fps-- it's more like 47.95 fps. So it may just be that this metadata software displays recording frame rate without the decimal places.

           

          It's also possible that the DP might have actually shot 47 fps for some reason. In some cases, DPs will change their recording frame rate to a slightly different fps because they're getting flickering from a light source when they shoot at the desired fps. 

           

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