sloooooow motion

I wanna have an animation that is SUPER slow motion. The fellas at the shop suggested rendering at 100 fps then importing and rendering out at 24 fps. Made sense.

Why doesnt Blender let me render at 100 fps?

Is there a better solution?

System: 2X 2.5 GHz Quadcore

*holy crap! I just realized how weak my POS computer has become. =\

One way is, you should have you animation speed equivalent to 100 frames = 1 second of animation (100FPS), this will be rendered as .png images for joining into a video. So if a walk animation normally takes 25 frames, make it take 100. Similarly slow down any simulation speed as desired.

Then, encode the frames into a video (using Blender most likely) at 25fps (for example). Then playing back 1 second of animation (100 frames) will take 4 seconds (25 frames/second) so you video will have slow motion at 1/4 speed.

Also it lets you set a custom framerate? underneath frame range, set the frame rate to custom and set the fps to 100.

Nope and nope.

I have 16 frames I want slowed way down. No matter what the custom Frame Rate (24 or 100), I always get 16 frames.

Evin if I scale the timeline within Blender, no matter what the frame rate, I still get the same number of rendered frames. ? That’s crudely inflexible.

I guess I’ll just fix it in After Effects.

Thats because your video generally should be played back at 24/25 fps. That means to make 16 frames slow down to 1/4 the speed, you will have to render 64 frames instead, which is 4x the frames. The action you had that normally takes 16 frames must also be spread across 64 instead as well.

Basically the more frames rendered to do the same ​thing will result in a slower motion when played back.

zeealpal nailed it. Setting a FPS value in Blender does not control how many frames are rendered, only how fast they are played back in the UI. You as the animator determine how many frames are rendered. Regardless of playback rate, if your action takes 1 second at that rate, you need to increase the number of frames the action takes by 10x if you want it to go 10x slower at the same rate.

If you already have your action keyframed for a certain speed and want to slow it, you can use Scale in the Dope Sheet or Action Editor to stretch it out. Alternately (and non-destructively) you can use the NLA Editor to scale an NLA strip by the desired factor, but this can lead to odd results if not done carefully, so proceed with caution.

Be aware that most physics sims like Cloth cannot be scaled in this fashion and do not slow down like keyframed actions do. Some sims have scale and/or time factors that can be adjusted, but the built-in parameter limits may prevent very large adjustment for slow motion.

Look, if you have 3 seconds of animation rendered at 24fps it’s gonna play fine (read: regular speed) at 24 fps.

Shouldn’t that same anim rendered at 100 fps play back SLOOOOOOW at 24 fps?

I’m simply asking to render 100 frames for every second on the timeline. Why else would you have a custom FPS setting?

If you set it to 100fps… it will be 100 frames per second.

you have something which is 16 frames, 16 frames is always going to be 16 frames… no matter what frame rate you specify. if you want these 16frames to be not 16 frames but actually 67 frames (67 / 24 * 100), use the time remapping tool, old is 24, new is 100

No because the action was originally keyed on a 24fps timeline.

Your animation timing was keyed for 24fps playback. If you change the setting and render for 100fps after you’ve set those keys and played the result at 100fps your animation would look fast. If you rendered that same animation at 12fps and played it back at 12fps your animation would look slow. If you render it at 100fps but played the result at 24fps as you say, your animation would look normal speed because that’s the fps you keyed the action for.

What you want to do is key the animation as you would normally but on a 80 or 100fps timeline from the get go, then switch to 24fps for rendering. Or render at the high fps setting and convert later in editing (if you don’t mind wasted rendertime for unused frames). Takes a bit of planning of course.

If the keys are already laid down on a 24fps timeline the only way to change the timing of the action is remapping before rendering as mentioned above or in a video editing app afterwards. Neither way will look as good tho. Edit: Well remapping might I don’t know -never tried it.

This is how they did the great slo-mo shots in Surf’s Up. The animators just keyed for normal action on a high FPS timeline (80fps I think) and the conversion was done down the line. It’s like shooting at high frame rates for nice smooth live action slow-motion shots. An old-school camera technique.


There are two aspects to frame rate (FPS).

  1. There is the rate of playback – that is what is set with the FPS setting in Blender, the target playback rate, the rate at which you intend to play the animation when it’s done. Remember – Playback rate. This will also adjust the frames/seconds scale in the Timeline – FPS is Frames Per Second, how many frames will pass in one second when played at that frame rate.

  2. For real-world cameras there is also the recording frame rate, which is the speed at which the camera actually records frames during the action it’s filming. Many cameras can do moderately fast frame rates, say up to 48FPS or maybe even up to 100 FPS. But it takes special engineering to get the rate way up there – they’ve even achieved rate of up to 1 million FPS or more, for scientific studies (like a-bomb explosions – cool as hell to see, not so good to be there). When recorded at a high frame rate, an action is slowed when played back (projector frame rate, or video frame rate) at a lower (slower) frame rate.

It’s pretty simple when you think about the actual physical situation of using real film – say a camera takes 2400 frames to record 1 second of of action (recording frame rate of 2400 FPS). A projector that plays it back at only 24 FPS will take 100 seconds to go through the action (2400 frames / 24 fps = 100 seconds), and that stretches the time out by 100X – a decent slow motion.

Blender’s virtual camera does not actually record existing action, it is used to create that action. So to get the same effect, you need to create the action spread out over many more frames than usual. So if you keyframe your action for 2400 frames and play it back at 24 fps it’ll look slow if that same action normally takes only 1 second (24 frames) to happen.

Here’s a little experiment – animate a ball to bounce for a couple of seconds, it doesn’t even have to be good animation, just 2 seconds worth of motion. Play it back with ALT+A. Then go into the Action editor, set the frame marker at the first frame of the action, select all the keyframes and scale them by 10 (key S, numpad 10, then Enter). Now play it back – 10X slower, because you now have 480 frames instead of 48 (if 24 fps was you chosen frame rate – it’s a common feature movie frame rate for historical reasons). More frames for an action, the slower it will appear at a given frame rate.

Hey that’s sounds like the best workflow for no-sim slow motion animation shots. Figure out where I want slow motion after keying normally on a 24fps timeline and edit the keys with scaling in the dopesheet.

I’ll use this method next time instead of the high fps timeline method. I guess that way is only needed for sims. Makes sense… I learned that reading about Surf’s Up, where the slo-mo shots included massive ocean wave sims.

Thanks for the tip, chipmasque.


Edit: Quick test… would be better if a scaled block of keys displaced the rest of the keys down the timeline. Still doable I think with some careful grabbing moving. Or maybe there’s a hidden shortcut I don’t remember. No matter, all shots should be planned ahead of time anyway. Would be nice to pick and one click for slo-mo in the middle of a shot tho.

OK I’m out. Don’t want to hijack the thread.

@ Larry Phillips: The example was kept really simple to illustrate the relationship between clip length (number of frames) and playback rate, so it didn’t account for all situations. You’re right, it’d be convenient to have the Dope Sheet/Action Editor account for scaling within non-scaled keyframes by readjusting the unaffected frames, but that’s not always desirable, so it may be better to keep it simple and rely on some up front planning.

For creating slow-motion sequences in the context of other clips or even portions of the same clip, it’s probably better to use the NLA Editor and its scaling options – better control imo, though at the expense of more advance preparation. Even greater control (and a simpler approach than the others) is to render the clip in segments – normal speed, slomo, normal speed – and use the VSE to glue it all together. This can make use of the Time Remapping option, but has to be used carefully if there are critically-synchronized frames in the animation, as the remapping can jigger that synchronization. Single-frame transitions (such as the keying of a constraint Influence) have to be treated with special care since they are also stretched to a number of frames.

One method that does not work well is to scale a clip in the VSE – it does not interpolate frames at all so the action gets jumpy.

This is the heart of the misunderstanding about frame rate – Blender does not render at a specific frame rate. It simply renders frames, and all these options for adjusting to slow the motion are means to change the number of frames being rendered. They rely on the setting of a target playback frame rate, and jiggering the number of frames being rendered based on that benchmark. But Blender’s rendering rate can vary from a few seconds per frame up to hours per frame depending on subject matter, and has nothing to do with the progress of the action relative to a target frame rate.

It may seem like a superfluous distinction but it’s actually a fundamental aspect of planning an animation. How fast does an action proceed? You first have to decide how fast it will be played back (Blender’s frame rate setting). That becomes the benchmark against which all animation is planned in terms of the time it will take in a sequence. All methods of manipulating the keyframed action are based on the assumption of that targeted frame rate, and are simply more or less sophisticated ways to increase or decrease the number of rendered frames Blender produces.

@Doublerbishop: Thanks for the “time remapping tool” suggestion. I was also having “slow motion/fast motion” issues. My mixamo animation weren’t downloading at the proper speeds and this is a huge time-saver (and hair saver:))

Dunno, might come handy -

Blender differs from Cinema4D in this case of FPS. Some would say Cinema4D works correctly and Blender does not, as far as FPS is concerned. Adjusting the FPS in Blender does not change your keyframes. Adjusting the FPS in Cinema4D does.

It does not mean you can not accomplish your goal in Blender it just means you have to do a little more work.

I would say that Cinema4D does what Chipmasque mentions above. When you change the FPS, they keyframes are scaled appropriately. In Blender that task is left for you to do. Simulations and particles are another task as well.

Sloooow motion is not just a button you push/click. It is shot planning.

You can use the time remapping function on the render panel.

By default its set to Old = 100, New = 100. But if you change the new to say 500 - the animation will run much slower.

It can have some unintended consequences if you are using particles etc - but for basic movement it seems to work ok.

Wait, if you set Blender to render at a high framerate you won’t need more frames to render the same amount of time?
edit:nvm, i was distracted and didn’t read the thread right

Ok, my 2 cents… PNG files have no frame rate. You can play them back at what ever frame rate you like. The key to good slow motion is to make the action (lets say one loop of a walk cycle) take more frames to complete. If the single loop normally takes 24 frames, then blender renders 24 png files. Then make the single loop take 240 frames. So Blender creates 240 png files. Then import them into the editor of your choice and play them back at the desired frame rate.

Yep - which can be achieve using the time remapping function.

It seems to work on the basis that motion that would normally take 100 frames (say moving a football from A to B) - now takes 500 frames. Therefore in 100 frames - the football has only moved 1/5th of the way from A to B.

If you want your animation to show the football going all the way from A to B - you have to render 500 frames. Of course playing this animation back at 25fps will take 20 seconds (as opposed to the 4 seconds it would take if you left the time remap at 100).

There are other ways to achieve a similar effect. When using particles you can adjust the timestep.