making 23.976fps into 24fps

wwjd wrote on 12/2/2013, 1:09 PM
k, incase this helps anyone else messing with making 23.976 frames per second DSLR into strait up 24p...

I recently took a 23.976 edit and switched properties to 24. Everything worked fine but where the cuts and clip connections are is now a little off. Like it is inbetween frames on the time line. This looks awkward, but does not really affect the edit - like it didn't wreck everything in one fell swoop, just the location LOOKS off. Stepping through frames with arrow keys, the cuts still seem fine, and moving the cut to the next frame worked fine, and broke nothing. Adding new clips fell to the correct frames but didn't line up with the off ones, because, well, it is tween frames and wouldn't make sense to do so.

So, to me, Vegas worked great at making 23.976 into 24.
In the future, I plan to START the project at 24 instead of 23.974 so things will line up correctly first time out.

Would love to hear other's experiences doing this.

With more cinema cameras aimed at 24p, more online places allowing 24p, and blu-ray and movies playing back 24p, I'd rather work in that space than the dated video standard of 23.976

Any reason NOT to? I am not making any TV broadcast material


videoITguy wrote on 12/2/2013, 1:27 PM
When dealing with your topic and the concerns that you should consider there is no one answer.
The variables are the 1) the camera that shot the footage at what setting 2) the capture method to digital file type 3) the project setting and 4) the software that you choose to use in the workflow.

For my own situation, I have learned that I can capture in Cineform what is very different from native SCS Vidcap does at these frame rate there is a fairly complicated situation that develops with what you are working with.
ddm wrote on 12/2/2013, 1:37 PM
Unless you plan on transferring your finished product to film, or actually shot on a camera that shoots real 24 frame, there is no reason or benefit to ever using 24 frame.
robwood wrote on 12/2/2013, 3:15 PM
23.976 is useful for DVD.
24 is useful for film.
both are available in BD.

i always match the project fps to that of the footage.
my Vegas projects were all 23.976 when DVD's were our delivery format.
now it's BD or online, and we moved to 24.

we used to use a script to disable resample whenever stuff moved from 23.976 to 24... we'd leave the audio alone because the clips were usually quite short.

but if frame-accurate mattered we changed the video playback rate by 1.001, then pitch changed the audio (lock to stretch) by .01730 (i think that was the number). tedious but worked great... should've written a script for it.
larry-peter wrote on 12/2/2013, 3:16 PM
Consider that a project frame rate change of this type will cause potential trouble even after your clip heads are returned to frame boundaries. None of the frames after frame 1 of each clip will be exactly aligned to frame boundaries, so you'll need to either disable resampling for all the clips (knowing that frames will dropped sporadically) or change the playback properties of the clips to 1.001 so you get a true 24f playback. You still may end up with strange rendering artifacts anytime there is a misalignment of frame to boundary.

I agree that unless your camera is originating 24, it would be best not to edit in 24. If you need to conform 23.976 to 24 for DCP cinema delivery, you'll end up rendering a image sequence at some step in the workflow anyway. You can import that image sequence into a 24f project, then use Elastique to shrink your audio track down to the same length as the 24f image sequence and re-render. Then you have the two components needed for a true 24fps delivery.
NormanPCN wrote on 12/2/2013, 3:31 PM
I am in NTSC land.
The few Blu-ray movies I have looked at out of curiosity were encoded as 23.976.

23.976 is not anything dated really. Yes, ATSC allows true 24/30/60 and similar formats but I doubt anyone uses them. The only normal "true 24" I know of is true film projection.
wwjd wrote on 12/2/2013, 3:31 PM
Thanks for the awesome feedback everyone, as always! I love learning this stuff here. :)

I'm definitely working up to DCP at 24. My camera shoots 23.976 (Canon) and I've going blu-ray or 4k and up, so I'm not seeing any reason to do anything in 23.x
So far, I don't have any clips longer than a couple seconds and much of the audio is replaced and aligned manually anyway.

And I've been DISABLING RESAMPLE since my very first render in Vegas. That feature hasn't helped me yet.

I think the frame boundry deal fixes it self since nothing was missing. I didn't correct all the misaligned parts but playback was fine and stepping through simply showed the same previous frame as it was before the change.... I think....
Chienworks wrote on 12/2/2013, 3:58 PM
Is there any reason the projection system can't handle 23.976? If it can (and almost certainly it can), then once again there's no reason to do any of this in 24. It's just asking for a ton of headaches you don't need.
wwjd wrote on 12/2/2013, 4:31 PM
that's the thing: I was expecting a ton of headaches, but didn't find even one. The movie theater projectors expect 24p - I don't think they play consumer stuff at all...

Logically, I can't see a reason to use 23.976... who needs .976 of a frame anyway these days? :D In the past timecode/sync etc were a huge deal. MOST of that (not all) is not even worth mentioning these days. Newer digital cameras, older film cameras shoot 24 frames every second, not 23 and a little more... My canon is stuck doing that, but I'd like match up with current trends

Found this on some website kinda sums up what I kinda know:

"23.976 is simply a television-friendly version of 24 fps that is traditionally used in film. While most people think television is broadcast at 30 frames per second, it's actually 29.976 (or 59.94 interlaced fields per second). Black and white TV was 30.00/60.00i, but the NTSC colour standard changed the time base slightly to help squeeze in the colour information. That has plagued us ever since."

Sounds like its time to dump old, goofy methods and move on.
Of course, I'm for 60p and up in theaters also :D

ddm wrote on 12/2/2013, 4:51 PM
>>>Logically, I can't see a reason to use 23.976... who needs .976 of a frame anyway these days?

In my mind, the question is Why shoot 24 frame anymore? it is a legacy from the film standard set close to 100 years ago. Frame rates are going up, as in 60p or perhaps 48p. The odd number, (23.976) which seems to be the stumbling block for some people, is just a mathamatical equation. Canon, in their DSLR's refer to 23.976 and 59.94 and 29.97 as 24, 60 and 30 respectively, for sanity's sake, as well as brevity's, really. The key question to ask yourself is what do I gain by taking footage shot at 23.98 and converting it to 24? Absolutely nothing, computers are great at math, there is no down side, but there are downsides, granted, they are usually fairly innocuous, to converting from 23.976 to 24.
wwjd wrote on 12/2/2013, 4:57 PM
because I think Digital Cinema Package expects 24p - same as film projections 24 frames per second - and I am aiming solely at Theater stuff.

I agree computers handle all the maths and in the end, most peeps never need worry about it.

Truthishly, I am experimenting with lots of stuff, and many modern cameras are shooting 24p - my next one will for sure.... so I want to get into that practice FIRST out of the gate. :D
ddm wrote on 12/2/2013, 6:39 PM
Most feature films shot in the United States are shot at 23.98, not because thats a better format, it's not, it's just more compatible with everything out there (post production equipment and default settings), as most commercial Bluray releases are also 23.98 even though they could be 24. All of the major 4k formats out there support 23.98 and 59.94 and are the default frame rates unless the post house sends out a decree that a certain production will be shot at true 24 or 60 and that memo would be in ALL CAPS because that is NOT the norm. Again, there is no quality difference or benefit from either frame rate, with the slight downside that most people assume 23.98 when you say 24 and you can get into problems when everyone is not on the same page.
johnmeyer wrote on 12/2/2013, 7:51 PM
I think there is some faulty thinking and bad advice being given that may lead to sub-optimal results (a.k.a., bad-looking video).

First, there are three frame rates you need to keep track of. To make things simple I am going to assume that there is only one type of video on the timeline.

1. The frame rate of the video itself.
2. The Vegas Project frame rate.
3. The frame rate of the final render.

None of these have to match each other, but you will get the best results for most applications if you DO match them all.

Video Frame Rate

For most types of video, this is "hard-wired" into the video header and you can't change it. For some types of video you can patch this header and cause the video to play back at a different rate. No frames are added, deleted, or duplicated. Instead, if you patch the header (using a utility like AVIFrate) the player you use to watch the video (e.g., Windows Media Player) will simply play more or fewer frames per second. This is exactly the same as changing the speed control on a movie film projector: the same number of frames are played, but they are played faster or slower.

Vegas Project Frame Rate

In some ways this is the least important of the three frame rates. If you want the smoothest, fastest timeline playback as possible, then this should be matched exactly to the frame rate of the media on the timline. This gives smooth playback because Vegas will do nothing to each frame in order to make it "conform" to some other frame rate. However, if you make any change to any of the project settings so that one or more of these settings does not match the media on the timeline, Vegas will attempt -- in real time -- to modify the video to show you what it will look like if it were to be rendered at that frame rate. Even small changes can have very significant consequences in how the video looks on the timeline and how quickly the video plays because Vegas is going to try to synthesize some intermediate frame in order to change the frame rate. Even the seemingly inconsequential change from 23.976 to 24.000 (or vice versa) will cause Vegas to interpolate all the intermediate frames. In fact, only one out each 999 frames will be untouched.

Final Render Frame Rate

The frame rate of the final render is completely independent of the frame rate you choose in the project properties. In fact, AFIK the only setting in project properties that has any impact on the final render is the Deinterlace setting.

So with that background, here is the message I want to convey: if you use a frame rate for the render which does not match the frame rate of the source, then almost every single frame of video will have to be synthesized from some combination of adjacent frames, unless you have disabled resample for every event. If you do that, then frames (and / or fields) will be added or dropped at the appropriate intervals in order to achieve the frame rate change. This will avoid the very soft look that the crude Vegas resample technology imparts to the video, but it will introduce a very strong temporal hiccup to the video, usually seen as a stagger or judder. It will be especially noticeable during smooth horizontal camera pans.

Whenever possible, use the same render frame rate as your original video.

farss wrote on 12/2/2013, 8:18 PM
It's a piece of cake to convert 23.976 to 24.000 fps using Vegas without harming a pixel.

Put 23.976 content onto 23.976 timeline, set ruler to Absolute Frames. Make note of how many frames long movie is.

Change project to 24.000. Ctl+Drag end of movie to read the same number of frames as noted above. Set Audio Resample to Elastique although for such a small pitch change it's unlikely to matter.

Assuming you render to the same codec as your source Vegas will almost certainly not recompress, instead it will Smart Render.

In effect this is the same as changing the header as John Meyer mentioned above.

I've used this same technique over the years to go from 23.976 and 24.000 to 25.000 fps many times over the years. The biggest issue here is pitch shifting the audio but since Vegas added the Elastique method that's been a piece of cake.

johnmeyer wrote on 12/2/2013, 9:00 PM

Ah yes, we had this discussion many years ago and I'd forgotten about that trick. It is an excellent workflow and should work perfectly, and since it doesn't require an external utility, it will work for any video.

One thing I'd add is to make sure that you keep the timeline set to Absolute Frames until you have finished the Ctrl-Drag operation. Also, make sure you have snap turned on. Finally, make sure to read Bob's description twice and recognize that you have to hold the Ctrl key while dragging.

[edit]I have not used Bob's method myself, but if I did, I think I would disable resample for all events. This probably isn't necessary, but the reason I would do it is that when I've created scripts, I have found that the internal roundoff errors in how Vegas handles time can sometimes lead to frame boundaries that don't quite line up. This in turn might (although probably won't) cause Vegas to try to resample (i.e., synthesize a frame) when it doesn't need to.

This step probably isn't necessary. Perhaps one of the Sony engineers who actually knows the internals could chime in.
Chienworks wrote on 12/3/2013, 12:44 AM
"Logically, I can't see a reason to use 23.976"

Well, there is one enormously huge and important reason to use it: it's what your camera shoots.

Most every digital playback program will handle whatever frame rate is in the header of the file. I'd be hard pressed to believe that the digital cinema projector ignores the file header and imposes a fixed 24fps playback. But (*shrug*) i've been wrong before.
farss wrote on 12/3/2013, 1:35 AM
[I]"Well, there is one enormously huge and important reason to use it: it's what your camera shoots."[/I]

It's a smidge more complexicated than that.
The NTSC film frame rate was chosen for technical reasons so that pulldown could be added to produce a NTSC compliant signal. Running a digital camera at 24.000 introduces additional technical complexity when it comes to providing external feeds from the camera for monitors. I think there's also other issues related to timecode and sync.

Grazie wrote on 12/3/2013, 2:26 AM
Wouldn't life be so straightforward if . . . . . .


ps, I am happy to use Bob's method to get from 23.976 >> 25 DVDs

wwjd wrote on 12/3/2013, 9:08 AM
Digital Cinema Package (to project at digital theaters) says Supported frame rates are 24, 25, 30, 48, 50, and 60 frames per second.
The projectors probably accept 23.976, but the DCP says it doesn't.
Granted, I am new to all this, and haven't built a DCP yet....
musicvid10 wrote on 12/3/2013, 10:06 AM
If the house takes DCDM there is no issue with the video, because it goes in as a TIFF sequence.

If you'll poke around the Cow and other places, you'll see that most of the discussion centers around the audio, and resampling for just the right length at 48 (or 96) Khz.
rs170a wrote on 12/3/2013, 10:27 AM
This PDF document may help (or it may confuse) some folks on this thread.
Despite it's name, it talks about time code variations.
Timebase Transition

Chienworks wrote on 12/3/2013, 10:51 AM
"24, 25, 30, 48, 50, and 60"

I'd really have to wonder if "30" isn't shorthand for 29.97002997 and "60" isn't shorthand for 59.94005994, both of which are more common than 30 and 60. And if that's the case then "24" might mean both 24 and 23.976. It would seem odd, short sighted, and self-undermining to build a projection system that couldn't handle some of the most common frame rates out there.
wwjd wrote on 12/3/2013, 11:18 AM
well the way I see it, is there is no such thing as a partial frame... no .976 of a full frame projected in real world time. the 23.976 means after a bunch of same sized/timed frames are shown, ONE will be skipped - one full frame skipped, to create the math to say "23.976 frames per second". in reality, all frame are timed the same.

I think that PDF posted above shows it as 24 actual frames shown in 23.976. But 23.976 exists to assist with the audio in broadcast (I think) or something.
But, it is 24 actual frames, why not just call it as it is, skip those annoying hundredeths of seconds?

I doubt the Digital Cinema Package creation consisting of TIFFs or JPEG2000 would be interested in .976 of a frame.

Nothing wrong with 23.976 - been working fine in the past and will continue to do so, but I want to play in full 24 moving forward.
By play, I mean PLAY as I am not doing anything professional.
larry-peter wrote on 12/3/2013, 11:31 AM
Please remember that all frame rates, fractional or not, are varying in TIME base only. There is never .976 of a frame, or any fractional part of a frame (or field, if that's the case). 23.976 fps is the same as saying 24 frames per 1.001 sec. All frames in will be seen in entirety, you just have to wait a little longer.
musicvid10 wrote on 12/3/2013, 11:39 AM
23.976 fps is not a fraction of a frame, it is 24 frames every 1.001001... seconds.