VMD-L Mailing List

From: John Stone (johns_at_ks.uiuc.edu)
Date: Sun Feb 09 2003 - 23:33:23 CST

Hi Sanjeev,
  The PPM files should look identical to what is shown on the screen,
unless you've selected one of image rescaling options. The PPM files
are not compressed. As for adjusting the frame rate. If you are
producing an MPEG-1 movie, there are really only 3 valid frame rates
that you can use: 24fps (film), 25fps (PAL), and 30fps (NTSC).
If you wish to achieve a frame rate other than one of those three,
you'll have to use frame replication in your source material to
give a different animation rate. If you can show me a PPM file that
has the quality problems you describe, I may be able to give you
further suggestions. No need to send the image to VMD-L however. :)

Thanks,
  John Stone
  vmd_at_ks.uiuc.edu

On Mon, Feb 10, 2003 at 11:11:57AM +0530, Sanjeev B.S. wrote:
> provide other suggestions. VMD itself doesn't do anything differently
> than it would if you used snapshot, but the back-end video compression
> that's done is very sensitive to the material that you start with,
> so it is important to feed it source material that will produce
> good results in the final animation format.
> +++ I saw the .ppm files were of poor resolution. So I guess the problem
> is with compression.
>
> By "delay time" I assume that you're referring to the playback frame rate
> of the final movie file? The current version of the vmdmovie script
> +++ I have a few snapshots now, that I have made seperately. I want to
> make a mpeg movie with these snapshots, such that there is some delay
> between the frames, with each image being a frame itself. Is it possible
> to do that in a simple way?
>
> Thanks a lot for the reply, Dr. Stone.
> -Sanjeev 

-- 
NIH Resource for Macromolecular Modeling and Bioinformatics
Beckman Institute for Advanced Science and Technology
University of Illinois, 405 N. Mathews Ave, Urbana, IL 61801
Email: johns_at_ks.uiuc.edu                 Phone: 217-244-3349              
  WWW: http://www.ks.uiuc.edu/~johns/      Fax: 217-244-6078