Is there any way to convert 24p captions to 24 fps?

[Michael Grenadier]

So I've been working on a complex restoration of a film documentary from the '80's with a director who's OCD is almost as severe as mine.  We had a a restoration and color correction done in Resolve at 4K 24 fps.  Our delivery specs at that point were 4K DCP (without captions), and a bluray and dvd masters.  (Gettting Encore to work was a well documented torment...) but he's now finishing negotiation a distribution deal with a company that will be doing DVD authoring and he's got a festival screening that will require a 4K DCP with a caption file.  DCP's need to be 24fps and of course DVD's have to be 24p (and blu-ray's can be either)...He spent an enormous amount of time tweaking the caption timing with a 24p output and I now need to tweak the caption file to work precisely for the 4K 24 fps file.  Welcome to my hell...  but I guess that's why I get the big bucks (if only).  Shouldn't be that big a deal to tweak the captions to match the 24fps file, but figured I'd ask if there's an automated solution...  (if anyone knows, it's probably Stan...).  At the moment, I'm using the automated scene detection so I'll hopefully have a pretty accurate display of the edits in the timeline which was what drove the director into such a frenzy of precision as he didn't want captions to proceed or last a frame or 2 over an edit point..  

thanks as always.  If anyone's interested in how things work out, speak up...and I'll add to this thread to report.  

[R Neil Haugen]

 I'm trying to puzzle the difference ... perhaps are you talking about 'full' 24fps versus 23.976?

Neil

[Michael Grenadier]

yes, precisely.  24p usually (always?) means 23.976.  And 24fps should always mean exactly 24 fps (although gotta say lots of manufacturers sometimes call 24p 24 fps).  And then there are those apps that call 23.976,   23.98 even though they mean 23.976 (are they paying by the decimal place?).    Am I obsessing about this?  maybe, but these things can be important and there is a noticeable drift between 24p and 24fps over the course of an hour...

[chrisw44157881]

DVD's are 23.976fps with 3:2 pulldown encoded for 29.97 interlaced fps to match NTSC displays.

[Stan Jones]

> He spent an enormous amount of time tweaking the caption timing with a 24p output and I now need to tweak the caption file to work precisely for the 4K 24 fps file. 

I'm not sure I followed the 23.976 vs 24.00 discussion re what you actually have. The current caption timing is on a 23.976 4K sequence? In PR or what is this a caption sidecar file from what?

In any event, step one, if you are using PR is to see what you have.... Is it in sync? How are you getting the captions in? What version of PR?

Stan

[Michael Grenadier]

sorry if I wasn't clear.  The captions were tweaked in a 24p 1080 sequence in Premiere since at that point I had thought that we only need captions for blu-ray and dvd which could both have a frame rate of 24p so hopefully one set of captions would work for both bluray and dvd.  I was supplied with a UHD prores(hq) output from resolve at 24 fps and simply "interpreted" the file as 23.976.  It's been 6 months and don't remember but I either used apple compressor or one of digital rebellions tools to do this so there was no interpolation of frames.  Premiere 2021 simply saw the file as 23.976 not 24fps... no frame blending.... Make sense?  So I output a file with the captions "burned in"  and the director gave me notes as to how to adjust the timing of the captions.  I made the adjustments (and line breaks, etc) as per his directions and then output again with the captions burned in which he approved (actually we went back and forth a few times... but you get the idea).  So I have a 24p (23.976 just so we're clear on this) premiere sequence with captions exactly as desired.   Now I'll just be deliverying a srt to the distributor and they'll do the dvd/bluray authoring but we now need to deliver a DCP (which cannot be 23.976 but had to be 24fps) for a film festival and they're requesting a srt file for some system they have to provide any one in the audience who cannot hear with a captioning experience somehow or other...  

That said, I did a scene edit detection on the original resolve 24fps output in a 24fps timeline so I'll be able to adjust captions so they don't overlap over cuts (which was the director's bugaboo...).   So I had a fantasy that there would be a sinple solution but with the edit  detection this should really should only take an hour or 2... with the 24fps sequence (with the original 24fps output from resolve) that I've done the edit detection on so I can quickly adjust the timing of the captions that were tweaked in the 23.976 sequence....  Make sense...?   I think I have a handle on this whether I'm making sense or not...  But thanks everyone for their help.

[Stan Jones · Accepted solution]

You have srt that is synced to a 23.976 sequence. You need srt that is synced to 24.000. Correct?

Subtitle Edit. Synchronization tab. "Change frame rate..." 

I have never done this, but that is what it says it does. Lots of other sync options there too...

I'll also note that I have never gotten  my head around PR, subtitles, and framerates. The pre-version 15 caption workflow allowed making some settings/import/export, but some formats simply do not allow some options. And PR would enforce some of those, but, it seemed to me, not others. So in the end, the file must be checked against the actually use case. And I believe that some players may convert from what they expect. 

Stan

[Michael Grenadier]

thanks Stan. I knew if anyone had the answer....  it'd be you.   As I said, now that I've got "edits" for every scene change, adjusting the captions if necessary should be a breeze assuming the scene edit detection is accurate.  Spot checked it and it seemed remarkable.    ah, for the days when someone else would be doing this part of the job...   

[FutureX5]

I know this is a couple of years old but where do you see "Subtitle Edit. Synchronizaiton tab. "Change frame rate..."" ?  Is this in AP or Resolve?  Does it still exist, I can't find it anywhere and need this exact function.  Convert a 23.976 SRT file to a 24 SRT.  There used to be a website https://subsyncer.com that did this but it's gone now.  

[Stan Jones]

It is in a third party program (Windows only) Subtitle Edit:

https://www.nikse.dk/subtitleedit

Stan

[FutureX5]

Thank you!  Your tool is the ONLY one I've found that actually does it correctly! I was going insane.

[Stan Jones]

FutureX5,

Thanks for reporting that this works.

Stan