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23.976 conversion to 24p

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Matt Campbell
23.976 conversion to 24p
on Dec 17, 2011 at 1:04:06 am

I have a 1920x1080, 2 minute video file that is 23.976 fps. I need to convert this to actual 24p for a submission of a digital file to some film showing, something or other. There specs specifically ask for 24p. Can I simply export my 23.98 timeline using Export, Quicktime Movie, self contained and simply change the output settings from Current Settings to the AJA IoHD:1080p 24 10 Bit Uncompressed? Will this give me a proper 23.98 to 24p conversion?

I've already tried exporting a reference file at 23.98 and using Compressor to convert the Frame Rate to 24p, turning on Frame Controls and using Best for Rate Conversion. This yielding crappy results. The audio and sync was fine, however what were my clean progressive frames, now I have ghosting in the hand gestures and movements.

So will back to my original question. Will FCP and the AJA codec/IoHD with hardware actually give me a proper 24p file? In my test, it looks ok, but I don't know for sure that this is the proper way to do so.

Help is greatly appreciated.

OS 10.6.7, Mac Pro 2 x 3 ghz quad-core intel xenon, 4 gb ram and AJA IoHD


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Shane Ross
Re: 23.976 conversion to 24p
on Dec 17, 2011 at 7:14:36 am

24p is 23.98 (23.976). So I'm a bit confused.

Do you mean actual TRUE 24fps? For film out? Because playing video out of a video out device is 23.98. The IOHD at 24p is 23.98.

Shane
Little Frog Post
Read my blog, Little Frog in High Def


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Matt Campbell
Re: 23.976 conversion to 24p
on Dec 17, 2011 at 2:27:32 pm

Yes Shane. Sorry for not clarifying. I need to output a digital file at True 24fps for some film device submission.

I tried outputting a digital file at the current settings of 23.976 using aja uncompressed. I then took it in compressor to do the frame rate conversion and setting frame controls to best under rate conversion. Result gave me artifacts, ghosting in hand movements and on my stills, some morphing crap from compressor redrawing those frames.

So I then just exported from my 23.98 timeline, this time selecting aja uncompressed 24p, rather than 23.98. This file looked good with no ghosting and frame blending stuff but can't really tell if it is a proper conversion. Audio and video looks to be in sync but not 100% sure about it.

How would you do with fop 7, compressor, AE or something else. Or am I over thinking it.

OS 10.6.7, Mac Pro 2 x 3 ghz quad-core intel xenon, 4 gb ram and AJA IoHD


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Mark Spano
Re: 23.976 conversion to 24p
on Dec 19, 2011 at 5:52:53 pm

[Matt Campbell] "Or am I over thinking it."

I would say yes. It's not really a conversion you're after here. You need a conform. A conform will take your 23.976 fps file and make it play back at 24 fps. A very very slight speed up, but won't change the quality of the frames at all. You can do this very easily with Cinema Tools. Open your 23.976 fps quicktime file in Cinema Tools, and choose Conform. Set it to 24.0 fps and click OK. Voila, a 24.0 fps quicktime, and look how fast that was. That's because nothing is changing in your file except the header info that tells it "hey play this at 24 instead of 23.976." You will notice that the audio sampling rate has changed by the same .1% as well (likely 48048 Hz instead of 48000 Hz). If that's OK with the delivery spec, then leave it, otherwise you'll need to resample the audio. This isn't hard to do, so check in if you need to.



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Adam Kitter
Re: 23.976 conversion to 24p
on Dec 20, 2011 at 4:39:41 pm

I agree with Matt, only one slight discrepancy. I'm not saying he is incorrect but incase you do happen to notice the audio shift there is a clever way around it. I think this is from Philip Bloom.

Before you conform your footage save another copy of the edit (you will need this for the native audio tracvk and timing) Conform will affectively and permanently change all the clips associated with that edit so, you may even want to backup your raw files.

Conform the copied footage to your correct frame rate

then using compressor export out, and in the adjustments you will want to change the timing. it will say the current run time, and if you notice it is different from your original edit, you can be sure your audio will be out.

So all you have to do is change the actual time of the conformed clip to the same time as the original. Not %100 sure if this removes frames or just changes the speed of the clip. But what you are left with is a edit that has the exact same timing, but with the new frame rate.

All you have to do is drop it in a new sequence, making sure it matches your clip settings and drop in the old audio.



Your change is so minor that you may not even notice any audio changes, but if the sync is important, like a music video or anything long, etc this trick may save you some aggrivation

hope it helps there is a detailed tutorial online if you need... not sure where tho hahah


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Matt Campbell
Re: 23.976 conversion to 24p
on Dec 20, 2011 at 10:37:14 pm

So all you have to do is change the actual time of the conformed clip to the same time as the original. Not %100 sure if this removes frames or just changes the speed of the clip. But what you are left with is a edit that has the exact same timing, but with the new frame rate.

Adam, what you're describing is a speed change in compressor. Changing the length of the clip will change the speed. This is not the proper way to do that. Compressor is then speeding up your clips to fit in the shortened time.

The method I had success with was as I described above. We've sent the file out and haven't heard anything back from them, so we assume that the true 24p file sent has worked for the film out. I've played down my original 23.976 and converted 24p files and both sound identical. No speed changes have occurred.

All we had to work with was that finished uncompressed 23.98 master. so my only option was to conform to 24p on export.

OS 10.6.7, Mac Pro 2 x 3 ghz quad-core intel xenon, 4 gb ram and AJA IoHD


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Chris Jones
Re: 23.976 conversion to 24p
on Jun 20, 2012 at 1:46:47 am

This is an old post and I'm not sure if anyone will see this reply...

Matt, I also need to convert 23.976 to true 24fps.

I was wondering if what you did in your last post ended up working for you.

Thanks!


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Matt Campbell
Re: 23.976 conversion to 24p
on Jun 20, 2012 at 2:40:04 am

Chris, I did have success with that file. Well at least I sure hope so. I never heard back from the facility that received the true 24p file for film out. Although I will say that using the Cinema Tools method and the bringing back your audio is prob the better way to do it. I also tried just dropping the 23.98 file into a 24p sequence rendered it out and exported. That also seemed to work.

What's funny is I just posted a similar secenario but now I have true 24p material and am conforming that for 23.98 which will then get pulldown added for gong out to broadcast at 29.97.

OS 10.6.7, Mac Pro 2 x 3 ghz quad-core intel xenon, 4 gb ram and AJA IoHD


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Chris Jones
Re: 23.976 conversion to 24p
on Jun 20, 2012 at 4:00:39 pm

Hey Matt,

Thanks for responding. This whole converting 23.976 to 24.00 is giving me a headache :) It seems a lot more complicated than it should be.

The 23.976 video I have is being added to a 24.00 16mm film edit, which is then going to a festival. For the video there is no sound, so that at least is not something I have to worry about.

Do you remember in Compressor how you made the conversion? It seems there are 2 ways to do it. In the Encoder you can set the Video setting to 24. Or in Frame controls you can change it a number of different ways.
The problem with frame controls is that I started to see jagged edges in the picture after I used it.

My main concern is that I just don't want to drop any frames (or add any frames). Do you remember if you changed the settings in the encoder from "Current" to "24" or did you do something in frame controls like 23.98@24 or "so source frames play at 24.00 fps"?

Thanks!

Also I was wondering if you had the link to your post about converting 24 to 23.976. I thought I might follow along with that and I might learn something.

You may also want to follow my post. There is a guy who just jumped in and did a bit of explaining - which just confused me more :)
Here it is:

http://forums.creativecow.net/readpost/8/1160608


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Inbal Lessner
Re: 23.976 conversion to 24p
on Oct 31, 2013 at 6:06:15 am

I'm not sure about sound conversion. Found a way that works but I feel like I'm making it too complicated.

I work in Avid.
Exported ProRes quicktime of the entire 90-minute HD film in 23.98
Conformed to 24.0 in Cinema Tools
Took 5.1 Mono Wav files from mixer and resampled in Wave Agent to 48,048
Imported Wav files back into a 24.0 fps Avid project and selected convert sample rate
(This is the only way I get audio files to come in at the correct duration and in sync to picture, but it's different than what I read other people do)

Export each 5.1 mono Wav file to a new Wav/48K/24-bit file

"Add surround audio" in Compressor, assigning 6 tracks + video and encode DCP using QubeMaster Xport plugin.

Does this sound right? Feels like too many steps.
Thanks in advance for your help.


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