PNG sequence renders jerky

Hey there guys,

I’m rendering out a PNG sequence for a video editor and he’s saying the output motion from Blender is jerky, but I’m rendering out as 25fps and all motion in using animation paths, so I’m not sure how to get the motion smoother for him.

Any ideas? Here’s my files…

http://we.tl/seNMem0kPC

The blender file is running at 651 frames long (0-650) and the video file is running at 622 frames long… Couple of potential problems

  1. not all frames rendered…

  2. someone along the way has either timewarped your video

  3. someone has imported the video into the wrong framerate / done some weird framerate conversions on it (AE is known to do this)

Thanks doublebishop,

I should have said the video was from a previous render, so just view it as a example of what the animation looks like. But I’ll ask the video editor what framerate the PNG sequence is coming in at.

He said he was adjusting it to 25fps.

PNG sequences often don’t play back smoothly because of the large filesize for each frame. PNGs are great for storing clean, usable data (like when you need 16-bit imagery, or when you’re using greenscreen footage), but for playback they’re downright awful. When I want to see things playing back in real-time, I usually have to pipe through a JPG sequence, or export an MP4, etc…

This isn’t necessarily what’s going on, but I’d suggest sending him a JPG sequence (at a reasonably high quality, say, 80%) and have him see if it plays back without stuttering. If it does, then his hard drives aren’t fast enough to handle PNG image sequences.

Yeah he said it was doing the same thing, and when he renders t out it still seems the same.

Thats the thing, he shouldnt have to adjust it. that is where the problem is occuring. You need to import it natively at 25fps not import and then adjust it to 25fps

He uses Premiere and im pretty sure it works like After Effects where the software guesses what framerate a sequence is coming in at.

But if you know how either of those import natively I’d love to know.

Dont use either program but a simple google search provided this –

https://forums.adobe.com/thread/1041688

In Premiere and AE just make sure to set the framerate of the SOURCE material along with the timeline/sequence. The mistake is when someone only sets the framerate of the TIMELINE and puts in a source with a non-matching framerate. E.G:

  • You create an animation intended to play at 25fps.
  • The editor imports the animation into Premiere, which interprets it (for instance) at 23.976fps
  • The editor creates a 25fps timeline and drops the 23.976fps shot into it.
  • (aaaaaarrrrgh!!! noooooooo!!!)

On the other hand:

  • The editor emails you and asks “what’s the frame rate for this image sequence?”
  • (yeeeessssss!!!)
  • The editor changes the animation to 25fps in Premiere, then puts it in a 25fps Timeline.
  • All is well with the world.

All experienced editors do this. As do all experienced visual effects people, animators, etc. Framerate is one of the first technical questions that should be asked, along with frame size, color space, and codec.

Incidentally, you can set a default frame rate for imported sequences in Adobe software. I believe mine defaulted to 29.97fps, and I changed that to 23.976, since that’s what I’m usually using.

Ok thanks guys, so here’s a reference for me in the future in AE

• Composition > Composition Settings > Frame rate > 25fps
• File > Project Settings > Timecode > Default base > 25fps
• After Effects > Preferences > Import > Sequence Footage > 25fps
• Then click on sequence in the Project window and make sure it’s frame rate is 25fps in it’s info

Has anyone had a chance to render say 2 seconds of my file I provided in my original post as a PNG sequence and then import it into some editing software to see if it’s still jerky because I know my video guy is still saying the motion is jerky when the balls are in top of the screen. I can see what he means and I’m wondering if it’s Blender? And if so what’s going on there?

I tried motion blur but that didn’t seem to work either, see my mp4 file here (6Mb):

http://we.tl/10BqR2ApbY

The first part of it shows with no motion blur and then 2nd part shows with, both still get jerky when a sphere is up the top of the screen.

If you want to play back the png sequence natively, try using DJV view – http://djv.sourceforge.net/ and enable memory caching. you can set the frame rate in the bottom left hand corner.

more then likely your png sequence is fine and your editor is doing something silly.

Posting that file was helpful. I believe you are experiencing what is often referred to as “judder.” There isn’t an easy fix for this. It happens with horizontal movement at certain medium-ish speeds. The best fix that I know of is to vary the speed a little bit: speed them up faster then slow them down when you want them to be read. If there weren’t words, you probably wouldn’t notice the judder as much. But such is life [sigh].

Thanks benu,

I’ll check that out.