On 23/12/2009 7:13 AM, Rainer M Krug wrote:
On Tue, Dec 22, 2009 at 8:10 PM, Duncan Murdoch <murd...@stats.uwo.ca
<mailto:murd...@stats.uwo.ca>> wrote:
On 22/12/2009 12:49 PM, Mark Knecht wrote:
On Mon, Dec 21, 2009 at 4:42 AM, Duncan Murdoch
<murd...@stats.uwo.ca <mailto:murd...@stats.uwo.ca>> wrote:
> I've just posted a demo made with the rgl package to Youtube,
visible here:
> http://www.youtube.com/watch?v=prdZWQD7L5c
>
> For future reference, here are the steps I used:
>
> 1. Design a shape to be displayed, and then play with the
animation
> functions to make it change over time. Use play3d to do it
live in R,
> movie3d to write the individual frames of the movie to .png
files.
>
> 2. Use the ffmpeg package (not an R package, a separate
project at
> http://ffmpeg.org) to convert the .png files to an .mp4 file.
The
> individual frames totalled about 1 GB; the compressed movie
is about 45 MB.
Could you please post the command line options you used for ffmpeg? I
remember I wanted to do an animation, also from .png, and I struggled a lot.
Sure. The png files were 1024 by 768, designed to be displayed at
24fps. The command line was
ffmpeg -b 2400000 -r 24 -i movie%03d.png -s xga movie.mp4
The -b option controls the target bit rate. The -r option says how many
frames per second, -i includes all the files (named things like
movie001.png, etc.), -s sets the output size, with xga being a quick way
to say 1024x768, and movie.mp4 is the output file. There are tons of
options to change codec, etc., but I found the -b option was the only
one I needed to play with.
Duncan Murdoch
Rainer
> 3. Upload to Youtube. I'm not a musician, so I had to use
one of their
> licensed background tracks, I couldn't write my own. I spent
a lot of time
> picking one and then adjusting the timing of the video to
compensate. Each
> render/upload cycle at full resolution took about an hour and
a half. It's
> a lot faster to render in a smaller window with fewer frames
per second, but
> it's still tedious. It's easier to synchronize if you
actually have a copy
> of the music locally, but Youtube doesn't let you download
their music. So
> the timing isn't perfect, but it's good enough for me!
>
> Duncan Murdoch
>
Cool enough video. Thanks for sharing.
I'm curious - did you do the equations for the knot in R? If so what
did they look like, assuming there's no reason you cannot share it.
The knot has equation
cbind(sin(theta)+2*sin(2*theta), 2*sin(3*theta),
cos(theta)-2*cos(2*theta))
The threads in the braid have equation
cbind(sin(theta) + sin(2*theta)/2, sin(theta-pi) + sin(2*theta)/2,
theta)
in the local coordinates of the knot.
Overall it's about 100 lines of R code, too ugly to post.
Duncan Murdoch
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--
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Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation
Biology, UCT), Dipl. Phys. (Germany)
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