Can anyone shed light on why this happens?
I have a 23.976 timeline with :30 spots (slate, black, spot, black x5)
All footage and graphics are 23.976.
I need to deliver 29.97 spots for broadcast.
If I export from the 23.976 timeline, asking the AME queue to do the frame rate conversion to 29.97/upper field, I get bad frames like this one (2) at the cuts.
It's more noticeable with graphics than the video (it's less forgiving when graphics are involved)
(Source input is 23.9767 progressive, output is 29.97 upper field)
If I take the same 23.976 timline, duplicate it, change the sequence settings to 29.97/upper field, then export using the AME queue, I get this result (1) - which is what I expected without having to change my sequence settings.
Sequence settings changed to:
Editing Mode: Custom
Same spot, same place on the timeline, same frame in the example.
Why does exporting :30 spots from a 23.976 timeline, asking AME to convert to 29.97/upper field give me the field/frame issue seen in #2?
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Changing frame-rates is a major pain. They don't actually compute easily. So computing 2:3 or 3:2 pull-downs while shifting from Progressive to Interlaced is a complex thing to do. It used to be that it was always better to go to AfterEffects for this.
What you've hit here is there are a couple ways that Premiere is trying to accomplish the pull-down and swap out to interlaced frames. One works vastly better for your needs ... as you've found. Just use that for your needs.
If you were going the other way, it might be that the one working best now works ... or could likely be you'd need the other method.
Neil, thanks for your answer! You mentioned AfterEffects used to be the preferred method for conforming 23.976 to 29.97. Is that still the case or is Premiere Pro just as good/better these days?
Ae is still preferred by a number of the people I know. Just because it's always worked well.
Yes, After Effects is better.
Export your 1080p23.976 :30 spots using Apple ProRes422.
Import those into After Effects, adding each one to a separate Composition. You can do this quickly by enabling "Create Compositon" in the Import dialog box and then choosing "Multiple Compositons" in the New Composition from Selection dialog box.
Add each Comp to the Render Queue and in the Render Settings change the Field Render pop-up menu from Off to Upper Field First and 3:2 Pulldown pop-up menu to WSSWW. Side note: Since you're introducing 3:2 pulldown for the 1st time, the cadence setting doesn't matter. You can save the Render Settings as a template to apply to the other Comps more quickly. You can also create a custom Output Module that uses Apple ProRes422 to more quickly set that as well.
The rendered result is 1080i29.97 :30 with pulldown using Apple ProRes422 that you can be confident about. It's important to note that you will see blended frames in these renders. These are not "bad frames" but rather are a result of 3:2 pulldown.
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Those are "blended frames" that result from the 3:2 pulldown process when performed on edited footage, not "bad frames". Due to the cadence pattern of 3:2 pulldown, you can't avoid it.
You should be good to deliver it with 3:2 pulldown as is.
I wish the old After Effects user manual was still around. It has a great diagram for the process.
There's a pretty good illustration of how you get from the original 23.976 frame to the odd video field and the even video field (resulting in the 29.97 frame) on the "Three-two pull down" Wilipedia page.
You might be tempted to convert your 23.976 clips to 29.97 prior to editing, but that means that you'll never be able to remove the 3:2 pulldown from the edited master (that is, pull the edited master back up).