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Question regarding fps and video speed for motion graphics

Forum|Forum|6 years ago
July 29, 2019
4 replies
9572 views

Hello,

I use after effects to do motion graphics, I like the smooth look of 60 fps so i always do it on 60 fps, I then stitch a few of the clips I export ( exported as .mov) in premiere pro to add final touches etc, sometimes i like to change the speed a bit, but I have noticed that this messes up the frame rate of the clip, may I have an advice as the to which the best way is to export that will keep it smooth and also makes me adjust speed without having to re-export?

Thanks

E

eikonoklastes

Legend

You're absolutely right about my complete lack of understanding of 29.97. I've been fortunate to have grown up in a PAL world, and have only ever used 25 FPS for broadcast, which, let's be honest here, makes far more practical sense than 29.97. I've never ever had to deal with 29.97 video, and I'm very thankful for that.

In any event, isn't NTSC an obsolete format for years now? Surely broadcasting stations in America have moved onto digital platforms that are more frame-rate agnostic? With online streaming rapidly taking over traditional broadcast this is moot anyway. I don't believe 29.97 needs to continue as a format for any reason any more when you can use a more sensible number like 25, 30, 50 or 60 (or even beyond if that's your jam).

Back to HFR, I'll reiterate - personally, I largely prefer 60 FPS, and not jut for motion graphics, for general video too. The difference is immediately apparent to me, and while it was initially jarring, is now more aesthetically pleasing to me than 30 FPS or below (with the odd creative LFR exceptions like stop motion work).

HFR, in my opinion, is where the future of video is. People are just not used to seeing it so they generally (currently) prefer the legacy, lower frame rates.

I am not aware of the Show Scan system, but I fail to see why watching 60 FPS on current hardware would cause severe headaches in anyone not already susceptible to that on any other frame rate. I've already watched a ton of 60 FPS content, and have never personally suffered from headaches because of this, neither have I heard of anyone else suffering because of it.

Regarding compositions, I'm sure filmmakers will adapt to higher frame rates and adjust compositions and lighting to compensate for any lack of isolation ability that's being caused by HFR.

Bandwidth doubles, file size doubles, but that would only be an issue if hardware was stagnant. It's not, and the wheel keeps turning, as we teeter on the bleeding edge, as always.

By the way, YouTube supports 60 FPS, and has for several years now. I believe most major video streaming platforms do. If your videos are being forced to lower frame rates, something is going wrong.

R

Rick Gerard

Community Expert

NTSC and PAL are still the standards for broadcast and cable. They are not dead or even dying. NTSC video was 30 fps until color came around. The frequency range they had to work with was set, just as FM and AM radio has frequency limits. When color was introduced the engineers had to figure out how to add 3 scan lines to the signal to carry the color information and the most workable solution was to slow down the frame rate. It's really pretty simple math. The only thing that got screwed up was the ability to divide up time into 30 uniform pieces so all they did was drop a couple of frame numbers every few seconds so the clocks stay accurate. The engineers that were developing PAL made allowances for the not yet developed color TV. They had a little wider bandwidth to work with so they could even give you a little higher resolution image.

As far as YouTube supporting 60, that is true. So does Vimeo. The reason your video is not available instantly is that YouTube and every other streaming service is busy recompressing your video and making multiple copies of it at different resolutions and data rates. The original video is not kept at all unless it precisely matches the current standard set by YouTube. No matter how careful you are with the settings it would be incredibly lucky if YouTube didn't recompress your master and then throw away the original. If the bandwidth is not available streaming services send you a smaller frame size and a lower frame rate. Frame rate goes away first. It's true that a lot of folks are on pretty fast connections, but if traffic is high or their system is not optimized, or there are four or five folks in the same house online at the same time your movie is not going to be delivered at 4K and 60 fps. There is nothing horribly wrong, that is the way the service is designed.

I spent a couple of years working on the team developing of two of the original video streaming formats. I also worked on a project where Left Eye and Right Eye images were recorded on alternate scan lines in HD interlaced video. We had to figure out how to fill in the missing scan lines to get a whole image for both images so that 3D movies could be projected in 3D theaters without losing half their resolution. The process was similar, predict where the pixels should be and make them fill in the holes. The only thing that has really changed is the algorithms used to sample color and predict where the pixels and where they are supposed to move have gotten a lot better and a lot easier for the CPU to work on. At the best settings, all streaming formats throw away most of the data from every other frame. CPU's are powerful enough to predict the motion of both color and pixels and pretty accurately give you smooth video playback and color. If you did a difference comparison between the original and the compressed footage you would be able to see the errors as colored fringes around most of the detail in the footage.

E

eikonoklastes

Legend

This has now drifted well off topic, so I'll break here. Thank you for your insights, Rick. I always enjoy reading your information-packed posts. See you around.

E

eikonoklastes

Legend

If you're retiming in Premiere, you want to use Optical Flow as your method of frame interpolation. While this has the potential to introduce artifacts, when it works, it produces the smoothest result possible, without having to re-animate.

Edit: Apologies, I see that Rick already suggested this.

OussK

Community Expert

As rick say's for motion graphic i think the 29.97 is the best option, even remember the extra time you will spend on rendering at 60 fps

E

eikonoklastes

Legend

Off topic, I'm curious why you both are recommending 29.97 as the best option for motion graphics. If the delivery isn't specifically for a platform that requires that frame rate, there is no inherent benefit to using this, and all the downside of having to deal with drop frame shenanigans.

Personally, I'm a big fan of 60 FPS for motion graphics. The silky smooth movement is very pleasing to my eye.

R

Rick Gerard

Community Expert

eikonoklastes wrote
Off topic, I'm curious why you both are recommending 29.97 as the best option for motion graphics. If the delivery isn't specifically for a platform that requires that frame rate, there is no inherent benefit to using this, and all the downside of having to deal with drop frame shenanigans.
Personally, I'm a big fan of 60 FPS for motion graphics. The silky smooth movement is very pleasing to my eye.

Silky smooth motion is a function of speed and frame rate. If your motion is not precisely an even number of pixels per frame edges are going to vibrate or judder. There are speed and frame rate combinations that make this visual anomaly worse, but unless motion blur is softening the edges enough to hide the stroboscopic effect, you have to follow the rules to get smooth motion. You do have more speeds available at 60 fps than 30 but this is really only critical when the motion is really slow. The human eye, when focused on a small screen or a TV screen across a room, is only able to focus on the edge details that is moving at a rate of 4 to 6 pixels per frame anyway.

I have fairly strong opinions about this stuff because I have spent years studying cinematography, television, video compression, and visual perception. I have even attended presentations using Douglas Trumbull's Show Scan system and talked to dozens of people after the presentation that had severe headaches from watching the high frame rate presentation. Mr. Trunbull has been promoting high frame rate immersive experiences since the 1960s but has still not caught on for a lot of reasons. HFR is very immersive if the viewing distance is correct, but even Mr. Trumbull says he would not film a dramatic piece in HFR because it is much harder to focus the viewer's attention to specific dramatic elements that contribute to the story.

29.97 is the NTSC standard. It is the frame rate that every broadcaster in the world that is on 60 Hz electricity uses. The PAL standard is 25 fps. On rare occasions, if you have cable, you can get 60 fps broadcasts of sporting events but only if your cable provider has installed the equipment that will handle that bandwidth all the way to your home and they have installed the equipment in your home that is capable of multiple frame rates.

Your comment about dealing with Drop Frame timecode indicates a complete lack of understanding of that system. NO frames are dropped, only frame numbers so that when the time code says 00;01;30;00 the time that has passed is actually exactly a minute and thirty seconds. If you didn't skip some frame numbers then when the timecode said 00:01:30:00 a minute and thirty and six-tenths of a second would have passed. There are no professionals that have any problem at all with Drop Frame Timecode.

It is almost impossible for anyone to tell the difference between 29.97 or 30 fps and 60. For dramatic presentations, there is a ton of evidence that even frame rates as high as 48 (The Hobbit) are not generally that pleasing to audiences especially on large screens when the viewing distance is not optimal. The lack of motion blur actually makes it harder to isolate the dramatic parts of the composition and gives the eye too many things to focus on at the same time. When you use 60 fps the file size doubles, bandwidth doubles if you want the same compression quality, and at best the render time doubles, most of your audience is going to get the content delivered at 30 fps anyway. If bandwidth or playback performance is degraded at all when playing back 60 fps footage the media players will all just drop frames.

It was not that long ago that everyone was all excited about the ability to shoot at 24 (23.976) so they could get that cinematic look. Turns out that more than 90% of the cinematic look is color grading. I started shooting commercials in the early 1970s on 35mm film but I ran my camera at 29.94 fps so we could transfer to tape without introducing 3:2 pulldown and I got a lot of work because the footage looked better on TV than almost all film that was transferred to tape. The commercials looked like they were shot on film because they were shot on film.

Use 60 if you like, but be aware that more than 90% of your audience would not be able to tell the difference and a fairly large percentage of the audience is going to have a 3rd party like YouTube deliver a version of your project to them that they have compressed and converted to 30 fps and in some cases resized to fit the bandwidth requirements of their connection.

R

Rick Gerard

Community Expert

60fps is less motion blur with the same movement. Jittery movement usually comes from the stroboscopic effect of frame rate and motion. That's why helicopter blades and wagon wheels sometimes look like they are turning the wrong way. YouTube and Vimeo will change the framerate of playback depending on bandwidth in the same way they change the frame size. Generally, 29.97 or 30 fps is all that is necessary to get a fairly wide range of motion speeds that don't have problems. If you are designing for the general public you really should be using 29.97 as your base frame rate. If you really want to render a 60fps comp for distribution but design and test at 30 you'll have a better chance of giving everyone that views the project a good experience. Only about 1 in 100 viewers will be able to tell the difference.

To help you fix the problem we need a lot more information about your workflow and a detailed description of what is going on in the frame. I'm guessing from your problem can be mitigated by turning on Optical Flow in Premiere Pro when you change speed. You could very easily end up with some stroboscopic effects or some duplicated frames.

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