24P, 24PA, timelines and film out - oh my

smelni

smelni

Veteran
I was just talking to someone at BH photo and it brought up some issues that i wanted to throw around here.

as an example - we are shooting a film on the HVX, DVCproHD and planning on printing to film (i know we should shoot on film then - but that isnt presently an option)

to get a film look we should shoot in 24P or 24PA.

24PA is better if we plan a film out.

now comes the complicated part - lets say you are using Avid for the edit. You import the footage into a 24 frames timeline and perform the pull down getting a perfect 24 frames/sec because of the 24PA. But the footage was encoded in a 60i stream resulting in really 29.97(might have gotten the decimal wrong). So wont the footage really be in a 23.XX timeline and not a 24 frame/sec timeline?

And then, how would that print to film considering film is true 24 frame/sec timeline. Wont the timecodes be wrong. How do they fill the dropped time? In addition if it were dropped into a true 24 frame/sec timeline wouldnt the audio drift because it was recorded at 29.xx?

So i was being told that film print places prefer to get 30 frame/sec timeline so they have stuff to fill the dropped time with.

After writing this message I am now even more confused.

help PLEASE :cheesy: :cheesy: :cheesy:
 
I thought that this issue of 24p and 24pa was only connected to NTSC. I think it doesn't exist in the HD world. Correct me, if I am wrong. At least that is what I thought.
 
Well, it will employ the 24p in 1080p just as it does in the DVX since there is no provision in the DVCProHD codec that will allow you to record 1080p24 straightforward (just as how the DVX has to record 24p to a 60i stream). DVCProHD allows for a 1080i recording and not 1080p, so although the capture from the HVX200 will be true 1080p24, it has to be carried within a 1080i stream, hence the need once again to have to reverse pulldown.

720p, on the other hand, can discretely record and lay to the acquisition media whatever frame rate you shoot as since the codec was designed for it.
 
when recording 1080 24p on the HVX you will stil use a 1080i stream with either 24p or 24pa

yes.. you can use a 23.976 fps timline or a 24 fps timline.. from the HVX footage. it doesnt make a real difference. the speed difference is so small its pretty trivial to worry about which exact timeline speed your using or what the CCD scanned at IMHO although you *should* use a true 24p timeline for a 24p filmout.. not that the projector is going to run at an exact 24 fps anyway.. but ..yeah.. it wont make a differnce for a film scan image wise. they just scan each fram. and then ot plays back at whatever speed the projector is running at . which is supposed to be 24fps, but i doubt a single film rojector in the world actually runs at an excactly precise 24fps. the only issue between the two is that the audio would be off after a while if it was a straght loooong clip and was not kept synched to the playback speed. since your NLE shoud keep it synched , and i doubt youll have any one shot that runs long enough to lose synch even if you NLE wasnt synching it...it shouldnt be an issue

and of course for video application you *should* use the 23.976
 
That makes sense - but the whole film is really one long clip when you are doing a film out - isnt it.

So at the beginning it will be in sync but by the end wont it be out of sync because the sound will be strictly at the 23.976 and the video frames have been laid into a 24 frame track?
 
I just rethought it and think i understand. You will sync each clip of the film - then output on a 24 frame timeline - I mistakenly though you would output on a 23.xx timeline - my brain broke i guess.

So then the sound is synced to the 24 frame and it works

i think i got it - maybe
 
the sound would stay in synch within any little clip in the film at 24fps. the difference is so minute it would take a while for it to go noticeably out of synch. when you put all the clips together .. you have a bunch of clips one after the other which are in synch.. then you output to a singular file.. which is also is in synch..just like in the NLE. but again, your NLE may adjust for the slight speed change by simply playing the audio that slight percentage faster anyway.. which would mean that you dont need to worry about snch in the first place.. the easy way t tell would be to import a looong 24p clip and just review the audio at the end. Im going to assume that all current NLES will handle it themselves, and youll see the end of the audio lining up with the end of the video on a true 24p timeline.. and all is well in care bear land.
 
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