Playback issues 24p and 23.98

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Playback issues 24p and 23.98

Hello,

I have assembled an edit (720 @24p) that must be layed back to D5 at 24 fps hard. NOT 23.976 due to a hardware conversion to 25fps that is coming. The issue i am having is that FCP seems to be playing back the edit at 23.98 despite all of the settings indicating 24 not 23.98. I can tell this is happening because audio sync is drifting, but when i plug in an audio file that has been converted to 23.976, the drift disappears. All of the clips have been generated or conformed by AE7 to 24 fps so all clips are consistant. Has anyone else seen anything like this before, and if so... any suggestions? Thanks in advance for the help.

bert

Dual 2.0 G5, Mac OS X (10.4.7), Huge Systems Raid 320 raid, Black Magic HD Hardware

Posted on Aug 17, 2006 10:45 AM

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Answer 1

Aug 17, 2006 11:03 AM in response to Bert Foster

It is my understanding that video does not have the ability to play back at true 24. Maybe D5 is different. In the past, when I have had to matchback to film from an exported 23.976 edl, it has never been a problem. I would lay off a 23.98 version onto the D5 tape, then try to do the conversion to 25 from that, just as a test.

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Answer 2

Shane Ross

Level 8

43,110 points

Aug 17, 2006 11:56 AM in response to Bert Foster

HD decks don't play 24 solid frames per second. Only film does that. 23.98 is the rate that HD decks run at for 24 frame footage. Even PAL doesn't run at 25 solid frames per second, it runs at 24.98 or something like that...

Shane

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Answer 3

Bert Foster Author

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Aug 17, 2006 1:14 PM in response to Shane Ross

Not that this helps the conversation much. Please see below- cut from the Panasonic AJHD3700B manual.

Video signals recorded
1080/23.98p, 1080/24p, 1080/25p, 1080/59.94i, 720/59.94p, 1080/50i,
576/50i, 480/59.94i switching

Now this doesn't help me much as i need 720 @ 24p. I know there are D5 decks that will record 720 @23.98p. I appreciate the help.

Dual 2.0 G5 Mac OS X (10.4.7) Huge Systems Raid 320 raid, Black Magic HD Hardware

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Answer 4

Aug 17, 2006 1:20 PM in response to Bert Foster

My assumption is that when they say 24p, that is completely different from 24 FPS. I believe they mean 24p, like 24p mode on panasonic cameras. If true, it would actually be 29.97, but the pulldown of 2,2,3,3,2 is what gives it the 24p "look". I would call panasonic and ask them what they mean by 24p.

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Answer 5

Shane Ross

Level 8

43,110 points

Aug 17, 2006 1:21 PM in response to Bert Foster

720p24 is 23.98. 1080p24 is 23.98.

24p is 23.98...unless we are talking in SD terms, in which case it is 29.97. Unless you shoot 24PA with the DVX-100 (100a, 100b) in which case it is 23.98.

Confused? I have no doubt...HD is plenty confusing. But, know that 24p in HD land runs at 23.98. DVCPRO HD, HDCAM, D5, HDCAM SR...all play and record 24p at 23.98. Even the deck you mentioned...which is DVCPRO HD...23.98.

Shane

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Answer 6

Bert Foster Author

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Aug 18, 2006 8:49 AM in response to Shane Ross

Just to be clear, I understand the difference between 24p, 23.976p, 24psf, 24pa, and all of the pulldown cadences using a 29.97 carrier. I am also familiar with the decks that i have been quoting from. These are D5 decks they are not DVCPROHD decks. And to be honest the question i asked originally had nothing to do with the output format. The question was about the abilities of FCP to handle 24p and 23.98p. As i said in my original post,FCP seems to be handling and playing 24p files at 23.98. It is to this question that i am asking for help. No doubt that HD formats are tricky, as is witnessed by the confusion in some of these posts. Thanks for the help.

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Answer 7

Shane Ross

Level 8

43,110 points

Aug 18, 2006 10:13 AM in response to Bert Foster

Bert...I don't know how many times I have to say this:

24p runs at 23.98 in HD. 23.976 to be exact, but we round up. 24psf is AJAs notation for 23.98, 24PA is panasonics 23.98 for DV.

D5 decks run at 23.98, not 24 solid frames per second. The only format that runs at 24 real frames per second is film. Period. 24 frames in video land is and always will be 23.98 (23.976 to be precise).

FCP can handle 23.98 in a variety of formats, from DV to DVCPRO HD to uncompressed 10-bit 4:4:4 HD. FCP can also edit 24 fps straight up for film ONLY. If you cut your video to 24 solid frames per second you will have lots of issues when you try to layback to tape.

24p is 23.98....24p is 23.98.

Shane

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Answer 8

Bert Foster Author

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Aug 21, 2006 8:46 AM in response to Shane Ross

Please!
This is rediculous... And you still haven't said a single word about the problem that i am reporting and asking the question about. The point of this whole discussion is that when i put together this edit at 24FPS in final cut as you say can be done clearly in your last post. The whole thing is playing back at 23.98, NOT 24fps. There are settings for both 24 and 23.98. This is the question.

I do not need a primer nor a lecture on techical specifications of HD tape formats. True integer 24p ABSOLUTLEY exists as a tape format. It exists both in D5 and in HDCAM and HDCAM SR.

"24p is 23.98....24p is 23.98."
YOU ARE INCORRECT!!!!!!

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Answer 9

Aug 21, 2006 11:29 AM in response to Bert Foster

Dude. No need to shout. Just like 30 fps runs at 29.97 in NTSC land, 24 fps runs at 23.98 in HD land. No question about it. Look it up.

Patrick

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Answer 10

Shane Ross

Level 8

43,110 points

Aug 21, 2006 11:31 AM in response to Bert Foster

The problem is that you don't believe me. And you should. I work with HD every day. I am editing DVCPRO HD..which is 23.98. I output to D5 and HDCAM...which is 23.98.

24 fps straight up is only for film. Period. End of sentence.

Go to hdforindies.com for more information. Click on the FAQ in the upper right hand corner.

And for pete's sake, when someone who knows more about a topic than you tells you something is a certain way...believe it. Do you yell at your teachers this way?

Shane

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Answer 11

Bert Foster Author

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Aug 21, 2006 1:01 PM in response to Shane Ross

Look, I am sorry to beat a dead horse. I also work with HD everyday. And layback to the formats we have discussed. This is a unique situation, that does not come up very often. I suggest that you contact the manufacturers of the gear as i have to discuss these technical aspects. You can lecture me and scold me all that you want. But the fact remains that if you consult the manuals for the decks in question, they are capable of doing what you claim does not exist. D5 records 1080@24P, and 23.98P... these are not the same thing. HDCAM SR does 24PsF and a 23.98 PsF... and these are not the same thing either.

To address your ending question; i believe that teachers teach, not preach. All good teachers i have ever had embrace being challenged, especially by hard data, and are willing to accept it when they are incorrect. I in no way am trying to start a ******* match or to insult your extensive knowledge of this subject. Please, look through the manuals for these machines and you will see what i am talking about. These are available for download from sony and panasonic.

....and you still haven't addressed the real question as possed to you now 3 times. Thanks for the time.

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Answer 12

Aug 21, 2006 1:49 PM in response to Bert Foster

wow. maybe try some local support in Mass. like boston camera perhaps, or national. they are a post house that focuses on lots of HD stuff.

http://nationalboston.com/

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Answer 13

Shane Ross

Level 8

43,110 points

Aug 21, 2006 3:13 PM in response to Bert Foster

OK...time to eat a little crow.

I just had a talk with the head of FilmLook (the guy who created the 24p process) and he threw a lot of info my way and I will do my best to spit back out what I retained.

D5 decks and HDCAM and HDCAM SR decks do have 24fps straight formats. But the people who use them are strictly film only people, and they rarely use it, if ever. 24fps footage cannot be viewed on an external monitor. Monitors refresh rates cannot handle 24 straight fps. So most people work with HD footage and film telecines at 23.98 (23.976) because mathmatically that matches up with the refresh rates and allows you to monitor your footage. Since many people do lots of various things in post and need the ability to view footage on an external monitor, they opt for the 23.98 frame rate.

Because of this, many telecine machines actually telecine to tape running at 23.98 fps...they slow down the film machine to match that of the tape speed to keep the transfers accurate. Then if they ever need to print back to film they are spot on. OR, if you shoot HD at 23.98 and then have that transferred to film, it is sped up ever so slightly (.013blahblahblah%) so that it matches frame for frame. This speed change is inperceptable (inpercievable?)...UNNOTICABLE anyway.

Because every post house I have dealt with only pushed the 23.98 frame rate, and really didn't mention 24fps was possible on those machines, I thought they weren't possible. I am sorry for my misconception on this matter and by relaying bad information.

I hope this helps.

Shane

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