Blender Support for 1080p 23.98 FPS?

hello all,

I am planning to produce a CG short in Blender with a required output of 1080p (1920 x1080 pixels) and 23.98 fps.

I have some concerns because it seems Blender’s Framespeed counter only works with whole numbers from my previous experience.

Is there any advice you can give if I want it to be 23.98 fps?
Can it support 23.98 fps in its Quicktime output?
And has anyone any advice about whether Blender can dub out audio in more formats other than FFMpeg?

Also for the technically minded… Assuming Blender works in 23.98 fps in Quicktime and FFMpeg, will it matter IF I dubbed a reel in FFMpeg to show the temporary audio at work… and then came up with a “beauty Render” in Quicktime for the Post-Production Sound Engineering?

Some advice would be appreciated.

for a few years now we have the frame rate divider. see wiki. use 1.001 and 24, same as ntsc which is 30 and 1.001

FFMPEG is just a container. It can hold quicktime movies.

well, good news for you: since that’s a HD format & the disc format for HD is BD, that supports 24fps, no need to use the old drop frame rate. So render @ 24fps. :smiley:

DVD video also does 24fps, so again, it’s a non issue.

If you’re not rendering to DVD/BD then the fps doesn’t matter. Most computers should handle at least 60fps @ SD no problem.

But either way, the FPS is pointless on blenders render unless you’re rendering to a video. Render as stills & then put that in to your NLE (blender too?). If it were me I’d aim for either 24 or 30fps when I’m animating, and since it’s easier @ 24fps, I’d aim @ multiples of that (24, 48, etc. good for slowmotion in post) & ignore 30.

Just to be pedantic, the fps numbers are actually:

film: 24
NTSC: 29.97
film on NTSC: 23.976

I’m pretty sure 23.98 isn’t used anywhere.

As Papasmurf said, you can use the frame-rate divider if you really need this.
24fps and 1.001 divider is close enough that you’d need a video 11.6 days long for the audio and video to get out of sync by 1 second at the end. A 2 hour movie wouldn’t even get 0.01 seconds off.
(EDIT: as per eye208’s post below, a divider of 1.001 is actually precisely correct.)

Also, the only case I can think of where this actually matters is if you’re editing a fairly long video in Blender’s sequencer.
Animation of individual shots, or editing a short video (a few minutes), doesn’t provide enough length for the difference to really matter. And then you can just do the video/audio encoding with an external app that supports 23.976fps

Having said all that… it would be nice if Blender could directly specify non-integer fps’s.

Just to be even more pedantic, the fps numbers are actually:

NTSC: 30/1.001
film on NTSC: 24/1.001

Ah, so you are right. I was under the impression that ntsc was 300.999 and 240.999 (i.e. 1/1000 slower than 30 and 24 fps respectively).

But it seems I was mistaken. Thanks for the correction. :slight_smile:


Thanks for all the replies!

I had just fired up Blender 2.50 and I was wondering what is this “Framerate Base”.
23.976 must be what I had been thinking of as 23.98.

The target specification literature had printed it as 23.98 but for all purposes it must be the same.

It is something I am discussing now with my Sound Engineer, and the framespeed is critical for some syncing and video conversion issues, but this Framerate Base entry is a godsend for me!

So it won’t matter what format I use? I can just plug in 24 as the framespeed and 1.001 as the framerate base and I end up with 23.976.

The length of the video being discussed is expected to be 11 minutes.

i’m curious why the sound guy wanted 23.976 (drop frame 24fps film that TV’s display). The DVD/BD player converts to 23.976 on the fly from 24p, all film based movies are burned to 24fps progressive to the DVD/BD. The only reason to make the render 23.976 is if you’re mixing it with video recorded on a camera (not film) at that framerate (because 60i cameras do that FPS to convert 60i to 24p).

Sounds to me like the app they’re using can’t do that part correctly, or they already mixed @ the wrong framerate (IE admobe’s video editing apps have the FPS wrong)

I’ve read that computer can’t calculate small numbers. It’s not precise. At least in java.

0.001 * 1000f = 0.999f.

and so on.

Well ok. To cut to the chase, I want to send a movie to SIGGRAPH 2011.

The standard they listed looks like this:

Computer Animation Festival High-Definition (HD) Submission Format
Basic Submission Guidelines

Accepted Video Codecs:
H.264 (must provide bit rate)
Accepted Video Resolutions:
1080p (1920x1080p) Preferred
1080i (1920x1080i)
720p (1280x720p)
Both pillar boxing and letter boxing are OK

Accepted Frame Rate:
60i (59.94i) fps Preferred
-23.98 fps
-30 fps
Audio Rate: 48.000 kHz

(These are the 2010 rules, but I expect practically all of it to carry over into 2011).

So… I wanted to work in the native format as much as possible, and the fps we wanted to go with was a bit low. So that’s why I was asking around about 23.98 fps.
I didn’t want to have to risk alterations from conversion.

first of all, good luck with your project and second, how many people will be working on the movie if you don’t mind me asking? 11 minutes is quite a bit to produce … given the deadline.

Are you thinking of using Blender 2.50 (or 2.49b … or soemthing different even)?

We are starting with a core group of 4 Blender artists, 1 composer, and 1 Sound Engineer.
We have varying levels of experience. All of us are volunteering for a chance to take on SIGGRAPH.

At some point our project will reach what I call “Concept Maturity”. At that stage in time it should be easy for 200 people (including you!) to jump in… Just wait for it… :wink:

We are going to use Blender 2.50 for Pre-Production. We expect Blender 2.50 to hit full release around middle of the year when we think Pre-Production should end. At any rate, 2.50’s Alpha build is already capable for Animatics… So… at this stage in time being an Alpha system doesn’t hinder the project.

I have another question: Has anybody done a Film Leader? This is the cyclic 10 second countdown prior to the start of a movie. Has some color test frames and what not. SIGGRAPH is requiring this and it is a Sound Syncing tool. They didn’t say it had to be the SMPTE Film Leader. I cannot find a Film Leader sample that is 23.976 frames and I am thinking of producing one myself in Blender.

Is this a good idea?

Thanks for the explanation. I actually had another question for you but it doesn’t matter now as those weird submission formats baffle me. :smiley: (really, no standard mpeg-2 or Quicktime?)

I’d stick to 24fps & when you’re all done just render to 23.blahblah fps in your NLE. I’m not sure what your audio guy is using, but normally you can bring the video in to the audio app & audio’s all samples so the FPS shouldn’t matter.

But hope you do well! A film festival is fun!

Do some tests renders. It all depends on the HDTV it is viewed on.

60fps is the minimum for 1080p, some go up to 120-160fps.
Most video game consoles that support 1080p are aimed at 32fps or faster.

Do some test renders, and test them on different hdtv’s before you render the entire animation. The faster HDTV’s have automatic Vsync so it will not matter if you are too slow, it will stage down to the FPS of the actual video.

BD movies play back @ 24fps progressive.

just looked it up: 23.976 IVTC Film framerate:

Glossary Inverse Telecine (IVTC)
Telecine is the process of converting 24 fps (cinema) source to 30 fps video (television) by adding pulldown fields. Inverse telecine, then, is the process of converting 30 fps (television) video to 24 fps (cinema) by removing pulldown.

So, for some strange reason, instead of them wanting it @ 24p they think you will render & edit @ NTSC standard & then convert it to this one.

Like i said before, it will automatically stage down, and Vsync to the video’s framerate to avoid tearing.

For the leader, a simple rotating “hand” alphaover a number countdown should work, with your sound booping every top of the hour. They use that to ensure you have the right framerate and that your sound is synced, and that you used gamma color correction :slight_smile: on the color card. Wikipedia has a colorcard, or just use an NTSC broadcast image card. They use that for adjusting the display device when they show it up on the big screen :slight_smile:

:stuck_out_tongue: It seems as if everybody here kinda understands the frame rate stuff, but not completely. Almost every post is half right and a half wrong.

History: NTSC video was originally set at 30 frames (more accurately, 60 fields) per second. This number was chosen because in the US the electrical grid is at 60 HZ and the old ray guns it the tubes worked best running at the same frequency as the AC power. (This is why video was at 25 fps / 50 fields in PAL areas because they knew how to do power girds right: 120V circuits in the US just plain suck)

When color TV came along, they wanted to be able to transmit both the old black&white video and color video in the same signal. So the sync for the color video was offset just enough so that it wouldn’t screw up the black&white sets. You had two different signals modulated onto the same broadcast bandwidth, and the sync determined which one you would see. So the newer color video was 30 frames / 60 fields per 1.001 seconds. People often say 29.97, but that is just an approximation.

Film is recorded at the standard 24 fps. To transfer to NTSC video, it is slowed down just slightly to 24 frames per 1.001 seconds. 30 fps “drop fame” just means that video frames are labeled as if they were 30 fps, but 2 frame numbers are dropped every minute except for every 10th minute to keep the time code from drifting away from what the real time is.

The 24/1.001 video content is the chopped into fields, and spliced together where 2 fields from different frames are doubled and spliced together so that every 4 frames is smoothly converted to 5 frames, producing 30/1.001 video. If you look closely, in these situations, 3 frames are interlaced and 2 are progressive. This is called telecine

Most professional DVDs are made this way, except that the video data is at 24/1.001 frame rate, and a flag in the MPEG2 stream tells the player to do telecine on the fly. (Saves space, allows for higher bitrate)

For HDTV, there is about every kind of frame size, frame rate, pixel aspect ratio, image ratio you could imagine.

Next time we’ll cover the frustrating issues that stem from pixel aspect ratios and YV12 color space… :wink:

P.S. FFMPEG is a FOSS video codec library, not a container format.

Thanks. This is similar to the story my Sound Engineer also emailed to me about. I also now understand that Film Leaders with the countdown date back to the time when film was played on reels that needed to run at one foot per second. (And back when I was little I always thought the countdown was there to get people excited about seeing the movie!).

It is incredible when you think about how these traditions in motor and electrical technology persist into the digital age.

Like someone mentioned above, our meetings also came to the conclusion that within a 3D application the fps rarely mattered because within apps like Blender you can animate in whatever framespeed you liked.

However, for a WYSIWYG result, and to avoid waste, I am opting to have our team do the native footage in 1920 x 1080 Quicktime Shell 23.976fps… And we have successfully produced a film leader in this format. (Which basically means the rest of our movie will be in this format).

Our Sound Engineer has the tools to allow not just final assembly but to use the QT shell with the MJPEG codec SIGGRAPH wants.

So there. Thanks again to everyone who gave advice. :slight_smile:


So I tried outputting a Film Leader with the following specs:

1920 x 1080 pixels, Quicktime M-JPEG-A
8 Seconds Long (“8 Picture Start”, countdown, black frames)

Framespeed: 24 div by 1.001 (for 23.976 fps).

Clip looks great in Blender Sequencer… Rendered 192 frames to produce 8 seconds.
Clip comes out seems fine… 8 Seconds long in QT Player.

But QT Pro and After Effects both claim the clip is just 23.01 fps.

Am I missing something?
Please help!