Camera Jumping

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Mikhail
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Camera Jumping

Post by Mikhail »

I think I may have asked a similar question before but, when we render out animations with camera movements the movie jumps. We were using illustrator backgrounds before and we thought that was the problem, but now all of our objects are built in anime and its still jumping. Is there any way to avoid this.

-Michael
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heyvern
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Post by heyvern »

Can you explain "the movie jumps" better?

If you key a camera movement it is the same as keying any other motion. The key interpolation "Step" will "jump" the movement with no smooth transition.

-vern
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synthsin75
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Post by synthsin75 »

I just tested this. When I exported as an AVI I get that jumping you describe for camera motion. I exported it again as a Quicktime MOV and it looks fine. I would suggest exporting to MOV format and then converting it if necessary.
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heyvern
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Post by heyvern »

I would just like to clear up the "jumping". Are you talking about "choppy" playback? Like the movie isn't playing all the frames?

Some types of compression and the size of the movie, action in the scene, power of the processor, video card in the computer etc etc will effect playback smoothness.

My theory is the AVIs are the same as the movie it is just that playback is skipping frames and it appears like camera moves are "jumping".

Can you describe the "jumping"? Is the camera actually "jumping" or moving to a spot that wasn't keyed? Or is it just not playing back all the frames? A lot of fast moving action in any compressed video format will cause the computer to have to work harder to uncompress each frame. When there is just a simple scene with little motion the compression is "better" easier on the "engine" (QT or Mediaplayer) because it can compress areas that don't move as much from frame to frame.

If you have a lot of motion like a camera move or an action scene with a lot of movement the compressor has to work "harder" and this slows down playback causing choppiness. Each frame is completely different. As an example a compressed movie of a talking head and only the mouth moves is going to be smaller in size than the same length scene of two kung-fu fighters jumping all over the place.

Like I said, I'm only guessing without a better description of the "jumping".

-vern
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synthsin75
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Post by synthsin75 »

I would just like to clear up the "jumping". Are you talking about "choppy" playback? Like the movie isn't playing all the frames?
Well I originally thought it might be caused by having 'allow frame skipping' enabled, but that didn't seem to make a difference. The jumping does appear to be dropped frames. The camera motion goes smooth for a bit then jumps, and so on.
I tested this more just making a circle and traking the camera to three or four different keyframes. AVI uncompressed has the most problem with this. I watched as it rendered, and the 'jumping' seems to be during the render, but it only shows in certain codecs.


Anyway, other compression codecs do much better. VP70 worked well for AVI. I have one codec that AS doesn't recognize, and another that crashes AS everytime. So it seems that AS has a limited number of codecs that it will 'play nice' with. Hope that helps.
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mkelley
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Post by mkelley »

Can you load in an uncompressed AVI into an editing program and step through frame by frame to make sure the camera is truly jumping?

I always render out single frames in AS and combine in Premiere to create my AVIs with no problems.
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synthsin75
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Post by synthsin75 »

Can you load in an uncompressed AVI into an editing program and step through frame by frame to make sure the camera is truly jumping?
I just did this. In After Effects it plays fine, but in every media player I tried (winamp, wmp, vlc, mpc, zplayer) it has the odd behavior of the timeline zooming to the end before the clip is done playing. I opened it with Windows Movie Maker to see what was happening, and it turns out that it only recognizes every seventh frame. Thus also effecting point motions.
I'm guessing that uncompressed is definitely not intended for end product viewing. Is uncompressed AVI strictly meant for compositing?
So no, there is no real 'jumping' going on. At least as far as I can tell. Mikhail, let us know if that clears anything up.
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heyvern
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Post by heyvern »

I just did this. In After Effects it plays fine, but in every media player I tried (winamp, wmp, vlc, mpc, zplayer) it has the odd behavior of the timeline zooming to the end before the clip is done playing.
Hold on there a moment.. it plays fine in AE... that means all the frames are rendered and the file is "okay". What happens in a "player" is that it tries to keep up with the fps of the file. If there isn't enough ram or the play back can't keep up it drops frames... in the playback ONLY. The render has nothing to do with it (except choosing a compression method).

If the playback is dropping frames in the winamp, wmp etc... it has nothing to do with the render it has to do with the video compression the player itself and the computer running it. Also if your hard drive is not "fast" enough or badly fragmented you can get choppy playback. Those frames have to be uncompressed and compressed really really really fast to get smooth playback.

For instance I watch some wmv files in QT using WMV player for the Mac. It is like a plugin sort of gizmo that plays wmv files in the QT player. I get different playback quality if I view in Media Player for mac than if I view it in WMV for QT. It could just be that the QT player is better in some cases.

No compression is almost always going to be "choppy" or "jumpy". There is no compression so each frame has to be pulled out of the video file format, shown to the screen, put back into the file, the next frame pulled out... etc etc. I am simplifying what is going on but that is the basic concept.

DVD movies work this way but they use hardware to speed up the viewing process. The file format for a movie on DVD is compressed otherwise a 2 hour movie wouldn't fit on a DVD.

-vern
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synthsin75
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Post by synthsin75 »

What happens in a "player" is that it tries to keep up with the fps of the file.
Seems to be so. I tested it by dropping my framerate below the seven per second limitation I found, and it look fairly good. No obvious jumping anyway.
If the playback is dropping frames in the winamp, wmp etc... it has nothing to do with the render it has to do with the video compression the player itself and the computer running it. Also if your hard drive is not "fast" enough or badly fragmented you can get choppy playback. Those frames have to be uncompressed and compressed really really really fast to get smooth playback.
Well, I know it's not my computer. It seems that my assumption about uncompressed not being meant for final output was correct.

Like I said earlier, just find a better compression codec.
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heyvern
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Post by heyvern »

I always use uncompressed for final output since I use another program to assemble the clips and THEN export to a final file.

If you are going straight from AS to a final animation that plays on a computer than you need to pick the right compression that will playback smoothly.

If you are importing into AE or something else like it you should use no compression from AS so that further editing and export from AE doesn't "re-compress" the file. Also AE probably has better options for optimizing the playback for different types, like web, DVD, etc.

I can't imagine a video that is higher than 7 fps should have problems. How big is it? HD? NTSC? I export NTSC from AS with no compression. It plays choppy but not that choppy... and I'm on a slow mac.

-vern
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