View Full Version : ever notice doubled frames when compiling frames into an animation?

03-11-2005, 08:28 PM
when i try to create (string together) an an animation from a previously rendered series of frames, i keep getting a doubled frame somewhere in the resulting movie file. (by doubled i mean that a certain frame is repeated and the frame that is supposed to be there is skipped. the animation ends up being the correct length but there's a visible glitch in motion) ...

at first i thought it might be because LW could not load the frame after the one that is doubled, since in that case LW would use the last one that worked. but that's not it, the frames are all fine and all work in other compositing apps.

could this be some kind of a timecode rounding problem?

i have seen this on both PC and Mac versions of LW

any ideas why or how to fix this?


03-14-2005, 12:36 AM
Are you are trying to load up an image sequence into LW that you then "compile" by rendering out as a backdrop sequence into an animation?

Give us some more details as to what exactly you are trying to do using what tool or app. Also into what codec you are trying to compile to.

This might help get it solved.


03-14-2005, 05:39 PM
yes, i am compiling an image sequence into an animation by rendering out as a backdrop sequence, using LW's compositing panel. for this purpose i am using LW 6.5 on a PC (although i have LW 8.2 on a Mac).

i have tried different codecs, it is not a codec problem -- the problem always shows up regardless of what codec is chosen. somewhere in the animation (300+ frames) i always get a "doubled frame". the frames themselves are all fine, since i finally used another app to compile and it worked fine.

note: i can even see LW making the mistake while working in layout: if i set display background to be background image (sequence), i see the background preview in the openGL view. as i progressively click through frames, LW will double (get stuck on) the some background frame (so it is definitely within LW itself). eg. background frame 191 shows up, then the same image gets held for frame 192, then 193 is loaded properly and it's back to normal...

sometimes it happens twice in the same anim if it is long enough (400-500 frames).


03-14-2005, 06:16 PM
i do this fairly often for quick fixes ..

but no, i've never seen this happen, even in previous versions of lw.

03-14-2005, 06:46 PM
When do these frames occur, are they at regular intervals? If so, what are these intervals?

I'm thinking along the lines of LW being set for 24 fps, and the codec being set for 25 fps, or something similar.

03-14-2005, 07:50 PM
Yea the frequency question is good to know the answer to. I think though - correct me if I am wrong - that you are saying it only happens once or twice in say a 300+ frame animation.

If it is in a frequency that is mathematically repeatable it might even be a drop frame issue. Each app has a different interface and thus different template for codecs. As an example in LW between avi. and .mov there are different templates. Though there are multiple-choice configurations in other aps for avi. that include a choice between 30 fps and 29.97 (drop frame) in layout from what I can see there are none. On the oitherhand in Layout (with quicktime selected in output files tab/ anim type, in the render options panel) clicking on options gives you a quicktime configuration panel and you can use the drop down to select the various frame rates - default is 30 fps and there is a choice for 29.97 among others.

I don't know what default is in lightwave for avi. But this data may help you do some more experimenting.

have you tried to use the offset option in the image sequence to see it the same frames repeat/

Example frame 200 and 201 are the same frame.

With offset set to 100 it is frames 100 and 101 .

or if you start rendeing at 199 to an end frame of 201 do you still get the repeated frames.

If it is a drop down issue these experiements would help because the "offfset/start from frame" examples would yeld different results because the codec would be calculating from the begining rendered frame not the LW scene file.

OK more on drop down.

29.97, is one NTSC standard. (Don't ask me why because I forget) All I know is there are two options: drop and non drop.

If you are rendering frames at 30 fps and the video codec is set to 29.97 it is loosing or gaining-however you look at the mess-.03 frames persecond. at 30 frames per second that's .9 frames per 30 seconds. times 30 frames that's .9 frames every 900 frames. It will lose one or gain one (.9) every 900 frames - depending on which side of your brain you are using.

Now that I have completely confused the issue and my math may be off but the point is as you can see it wont drop frames that often. This might be it.

Remember that LW might have .avi set as a default to 29.97.

Have you tried the example with .mov?

Also have you tried to just render frames and see what it does - save RGB and not animation.

One way or another we'll get this nailed!


03-15-2005, 01:58 AM
Funny you should mention this. Back in the 6.0 days it happened to me once (on an animation with 300+ frames). I ended up thinking that I had made some kind of mistake in the editing or something. But when I checked the frame sequence afterwards, one of the frames was doubled (somewhere in the middle of the sequence).

However, this was a long time ago, so I can't look it up.

03-22-2005, 06:22 PM
i agree that it's a drop frame issue, i had mentioned "timecode rounding problem"... what i meant to say was "drop frame". :)

in any case, i did not have the luxury of spending the time that would be required to properly do all these tests, *especially* on such an older version of LW (6.5). seems the 6 series may be the only one with this issue.

8.x seems to work just fine.

thanks again,