NEWS
Avid Does the Math
23.976 vs. 24 fps for NLE by Bill Stetz
Avid
Technology has set the table for an industry understanding of editing
set-ups important to the commencement of any project. Michael Phillips,
Avid's principal product designer, conducted a seminar, entitled "When
and How to Use: 23.976 fps vs. 24 fps Project Types," at the Darryl
F. Zanuck Theatre on the 20th Century Fox lot for a group of over
100 participants. Addressing a topic little understood and often confusing
for any nonlinear editing (NLE) user. This display of PowerPoint screens
depicted the various scenarios of editing and decisions of whether
to originate an Avid session in 23.976 or 24 fps. Reluctant to spell
out any one or several recipes for a project start, Phillips stressed
throughout the evening that editors should prudently pre-determine
where the creative project is to begin and end before making this
decision, thereby avoiding most if not all of the problems down the
project's delivery road. This means that the NLE editor must either
spearhead the challenge or follow the lead to be on common ground
with the director, director of photography, sound editors/mixers and
delivery platform specialist from the get-go for any project under
consideration.
If there were a bottom line, it would be to use 23.976 fps for your editing project—but the bottom line is not always what it appears. In a no-sales-hype presentation, Phillips explained that any creative project (film or tape), when entering the NLE project, would benefit by adopting the 23.976 fps standard. The simple reason for this is that the reoccurring 1,000th frame hiccup, which occurs during a 3:2 pulldown transfer while digitizing to the NTSC video standard, will be avoided. Sync of picture with the audio track is always recorded at 48,000 kHz will not be disturbed. Digitizing the picture at 23.976 fps automatically and mathematically avoids that little quirk. Secondly, all recent digital cameras—with the exception of a couple of high-end high-definition cameras that tout the 24p film acquisition format and are switchable from 23.976 to 24 fps—are actually recording at 23.976 to begin with, and a transfer to an NLE system makes the picture and audio sync issue moot by launching the project at this frame rate. Unless your acquisition camera is of a narrowgroup specifically set to 24.000 fps, you will most likely wind up with an original picture that was recorded at the slower frame rate.
Also, projects that will end on DVD or digital tape formats as a finish will benefit by using audio that is unadjusted and delivered, edited and processed at the standard 48,000 kHz sample rate (native for DV and MPEG-2 picture for DVD authoring) with the accompanying 23.976 fps picture rate.
Things become a little more particular when picture (film) is recorded at 24 fps. Then transfers to the NLE environment require an adjustment of audio to slow it down to match a 23.976 fps standard. Audio work and effects are therefore challenged to maintain sync with picture when reunited at the appropriate point of workflow.
The seminar notes and presentation materials for "When and How to Use: 23.976 fps vs. 24 fps Project Types" are available online at http:/www.editors guild.com/v2/magazine/Newsletter/AVID23_24. As part of its ongoing outreach to the editing community, Avid will be presenting additional seminars on pertinent topics. To be placed on the contact list for future presentions, e-mail Sandy_Yunt@avid.com. For upcoming event information, check the Avid website at http://www.avid.com/events/localEvents.asp.
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