29.97 Drop Frame Broken?

Hi,

Logic cannot differentiate between 29.97NDF and 29.97DF.

So it uses NDF. As do most TV post houses. Logic techs left it this way from long ago.

I would recommend you use 29.97NDF, as this is the standard 99% of the time.

Cheers

noeq,

Normally I wouldn't post in on this forum, but on this subject I will...

I can confirm that Logic 7 behaves properly with respect to 29.97 df and ndf, though I'm not in a position to test it out with L8.

With all due respect, your advice that the OP should work at nd is misplaced. If that's the timecode that his editor is working at (and has prepared a workprint for the OP accordingly), he has no choice but to work at that frame rate. Otherwise Logic's SMPTE counter, event positions, etc., will not match the BITC in the picture.

On the flip side, working at df is usually an indication that the film isn't a final cut, which is bad for any composer! Now, if the editor has mistakedly burned a work print at df and it should be nd, that's a different story. I would suggest that the OP double-checks with his editor as to what the frame rate should be. I'd further suggest that if the OP isn't working to a final cut that he waits until he can get one. 😉

Over and out.

It is the same old story with the same old confusion. and I don't even know where to start:

* If you are setting the sample rate on your DAW or any digital device, you are setting the CLOCK FREQUENCY, or CLOCK SPEED, i.e. 44kHz, 48kHz. You determine a speed on how fast the ADC cuts the analog wave form into discrete samples or how fast the DAC puts each sample back together.
* If you look at SMPTE timecode you see number like 24fps, 30fps, 29.97fps. This is called the Frame Rate. However here is the big difference. *The Frame Rate tells you TWO things*. Yes 2TWO ! If you are not aware of that, then you might have difficulties understanding frame rates like 29.97df or 23.976

_The two informations are:_

1) The SPEED or FREQUENCY or RATE. How fast do you take samples (in this case picture frames), or how often you take a picture snapshot: 24 times per second, 30 times per second or an uneven number 29.97 times per second. This is called the "FRAME RATE" measured in "fps" frames per second. Again just a clocking information. How fast the frames where taken and therefore how fast (at what speed) do you have to put the frames back together to get everything back into sync.

2) The second information in the Frame Rate number deals with LABELING. Now this is important. It tells you how to label each frame, or how you count them. "0 to 29 and start again" or "0 to 29 and start again, but at specific minutes you start counting from 2 to 29". You see these are just rules how you label each frame. The reason for some of the rules have to do with history and how some not so smart engineers came up with bad compromises.

_One Example;_
The Frame Rate 29.97df tells you that the clock rate is 29.97 frames per second and the numbering of the frames follows the "drop frame" rules. If you sync two devices, you only send the clock speed. In order that the slave counts the frames exactly the same way, you have to make sure to to set the Frame Rate on the slave to the correct number. Now it counts the frames in the same way as the master.


Everybody outside the USA who doesn't have to deal with NTSC video standard is lucky and might not even be aware of that dual information in the Frame Rate setting because with 24f (film standard) or 25f (PAL standard the clock speed and label convention is the same, i.e. sampling the picture 25 times per second and labeling the frames 0 to 24.

One major feature addition to L8 was the 23.976 frame rate. Whoever had to work in the past with animation, feature film output from an Avid or HD production was faced with 24f picture clocked to 29.97 fps. And selecting that new Frame Rate in the Synchronization Setting lets you do that. I clocks Logic with 29.97 fps but counts the frames from 0 to 23.

_My little rant:_
With the transition to HDTV, engineers had the chance to get rid of that 29.97 nonsense clock speed. But guess what, they carried it over. Of course they saved money by keeping their house clock in their facility at 29.97 but if you think of all the continuing errors based on those clock speed mismatches for all the future projects you will see that the monetary damage will be much bigger, it will just be equally spread to everybody involved in the project. If you work with film, just think on how many hours of troubleshooting you are wasted just to deal with video sync issues (most likely 29.97fps related)

Edgar,

The info you provided bears repeating, for sure. But I'm not sure it relates to this topic... Of course the frame rate of 29.97 nd or df is 29.97 fps, but it's how the frames are numbered -- and how Logic displays the timecode according to nd or df rules is the issue, no?

noeqplease wrote:

I would recommend you use 29.97NDF, as this is the standard 99% of the time.

noquplease, with all due respect I find this statement pretty dangerous.

First of all if you try to figure out a sync issue, it is not important what you recommend to use, just because it is 99% of the time correct. This could get you in serious trouble if you are dealing the 1% chance.

Let me try some different recommendations:
1) Don't even try to put down a single note in Logic until your sync setup (Logic-Video, Logic-PT) is rock solid. That means 100% !
2) Make sure the Logic TC reader matches exactly the BITC, throughout the length of the video.
3) If you have sync pops at the beginning AND end of the video, even better
4) Check your TC sync once a while you working on it. You might have shifted something (Tempo, KeyCommands, etc) without noticing it.
5) If you are having trouble syncing the material (video from post production) check if the video you received is absolutely correct. The more you understand about frame rates and the tools how to troubleshoot potential problems the better you can communicate with the person in charge who made the video output.
6) The lower the budget of the project the higher the chance that you might have a better understanding of sync issues than the guy who send you the video material.
7) - - add you own experience - -

Hi edgar and iScwhartz,

Thanks for the clarifications.

I must have had this in my memory from an old Logic version...

Cheers

Hi there, I was able to slave Pro-tool to Logic in drop-frame until I updated to 8.0.1.
Hence, 8.0 worked perfectly as did all previous version.

That'll teach me to fiddle with something that allready works.

cheers mate.

Hope Logic will fix the issue in version 8.2