Sunday 9 September 2012

24fps film master to 25fps DigiBeta tape master

In a film 24fps project, one often has to make PAL outputs, at 25fps.

Here we refer to 24fps as 'true 24 fps' not like 23.976fps which is called 24fps in NTSC countries.

First, on quality... 

If the FCP system is outputting ProRes, then it is of the exact same quality that Smoke on Mac would output. If it were a Smoke on Linux then that would not be able to output ProRes or DNxHD so there is no way to compare.
In my experience, an FCP ProRes (HQ and 4444) or Avid MC output (DNxHD145, 220, 220x or 444) is visible indistinguishable from a Smoke, eQ or Baselight uncompressed source, if the original is a compressed video (for eg. Canon, Sony F3, Ex1/3, Alexa, etc). For an original film source scanned input, it may matter.

For the DigiBeta (or any other 25fps) output, there are two methods.

1. We run the 24fps source as '24+1' or 24@25 where we play the source at 24fps but the video output is 25fps. Only FCP 7 or Avid MC can do this, Smoke cannot. Here one frame is repeated every second. There is a visible judder once per second, just like we see on an external monitor during editing a 24fps project in Avid MC or FCP 7. This is the preferred method in India as it leaves the sound untouched.

2. We run the 24fps source at 104% speed. In this method one's 24fps master is 'conformed' to 25fps, or made 4% fast to be able to play into a DigiBeta. No frames are repeated, and all 24 frames are played every second. This method is possible in Smoke or eQ and is the preferred method in the Eu or UK. But in India we do not make masters like this as the sound runs 4% faster too and this changes the pitch and tempo. No music director would permit this in India.

So, depending on where the DigiBeta tape is headed, one selects any one of the methods above.

HDCam, HDCamSR, D-5can all run at 24fps, so no conversion is needed if your tape/disk is one of these.

For the DVD, if its PAL 25fps, you need to do one of these above two methods. For an NTSC DVD there are established methods of converting 24fps (actually 23.98fps) to 29.97 fps by repeating 6 frames. This is invisible and involves no pitch change. Almost every single English movie DVD one has ever seen, uses this (23.98-24 pull down) method. There are also '24fps DVDs' in NTSC.

Blu-ray DVDs run at 24fps so conversion is needed. 

Web movies can run at any fps from 24 to 60 fps. Most computer monitors, iPhones, smartphones, and iPads on which viewers see movies, have no specific fps, so here too anything will work without conversion.

1 comment:

  1. Is there a simple way to convert canon footage shot on 24 fps , actually 23.98 as said, to edit on FCP 7, and prepare for D5 tape and reel...


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