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Odd Dailies Request, Flicker.


Michael Wynne
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So I’m being requested from dailies to work in pull up 48.048 / 24fps since the DP wants to shoot @ true 24fps to reduce the possibility of flicker with lighting set ups. We are not shooting on film and footage will be pulled down 1% along with sound to be edited and broadcasted at 23.98.  The dailies company said this is somehow common with Canadian DP’s who feel this is a solution to mitigate flicker issues.  So, The dailies company wants to modify my sound rolls and sample rate convert my Cantar X3 files back down with SD’s Wave agent before hitting editorial to get it all back down to 23.976 and assures me it will be seamless and not affect sound. What’s odd to me is there doing all this just to accommodate the possibility of flicker and it’s not even a heavy VFX show.  I feel like this could create a whole heap of issues not only in my cart workflow with Dante sample rate sync with clocking and pro tools playback but it could also create unnecessary confusion down the line with audio post who will want to work with the original sound rolls.

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17 minutes ago, Michael Wynne said:

will be pulled down 1%

You mean 0.1 %

17 minutes ago, Michael Wynne said:

and broadcasted at 23.98

It's either 23.976 but more likely 29.97 with added pulldown.

 

 

18 minutes ago, Michael Wynne said:

who feel this is a solution to mitigate flicker issues

Makes no sense in my book. Net Frequency is either 50 or 60 Hz, so both 23.976 and 24 will suffer from flicker the same wat.

 

19 minutes ago, Michael Wynne said:

sample rate convert

Forcing a new sample rate is just 4 bytes change, nothing will change to the sound, except the pitch will shift by 0.1 %, even for the best of us unnoticable I would think. (Artefact from actual sample rate conversions will be way more noticable.
But again, I don' think shooting 24 to fix flicker is a wise idea, since that introduces 'complexity', and I totally fail to see how this cold help.

 

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Hello Michael,

We used this technique in early 2021, utilizing the "48048 F-Mode" sample rate on a Deva V and SD 688.  The F-Mode stamp was important for the post house to allow their workflow to properly handle the draw down.  My understanding is that ProTools or other software will attempt to re-sample the files if the Metadata reads something other than the 48000 the software is expecting.  The FMode Metadata stops resampling from occurring by tricking the program into treating it as 48000.

 

As for the flicker, the DP we worked with mentioned specifically screens, phones and lighting which they cannot control (location specific) are the main places they have found this technique to provide better outcomes.

 

I re-visited this link to recall some specifics: https://www.trewaudio.com/articles/48048-khz/

 

This section was the most helpful when I originally started down this path:

 

"Generally speaking, the preferred sound delivery file format for post-production is Broadcast WAV Polyphonic, often shortened to BWF-P. These multi-track files are preferred over monophonic Broadcast WAV files because they are easier to handle (although some equipment may only deal with the mono variety, so be sure to check with the post house before delivering). While BWF-P files may be the best way to deliver to Pro Tools, the software cannot deal with them directly. Files must be converted to mono on import and it is this conversion process that makes –F mode so important. If these files are identified by Pro Tools as being 48.048 kHz, then they will be automatically sample rate converted to 48 kHz on the way in, negating the pull-down effect."

 

 

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