The making of multimedia files

If normal modes are animated and the user selects Save drawing/TIFF from the main window menu a series of TIFF files is written out, one for each frame of the animation (currently 20 frames which cannot be changed by the user). These TIFF files can easily be converted to a video file (MPEG) showing the animation using standard image manipulation tools from the Internet. One possible MPEG encoder is mpeg_encode which is available from ftp://mm-ftp.CS.Berkeley.EDU via anonymous ftp. This encoder expects its input files either in PPM, PNM, or YUV format. To convert the TIFF files written by VIEWMOL you can use the PBMPLUS or NETPBM libraries which have a filter tifftopnm (you also need pnmflip, since tifftopnm changes the orientation of the picture). The following shell script will do the conversion (for sh and ksh users) if the default files from VIEWMOL have been used:
for i in vm_image*.tiff
do
  j=`basename $i tiff`pnm
  tifftopnm $i | pnmflip -topbottom > $j
done
The resulting PNM files can then be processed by mpeg_encode to produce a MPEG file which can, e. g., be included into a World Wide Web document.

Selecting Save drawing/Rayshade from the main window menu with an animation running will write a series of 20 input files for RAYSHADE. These files can also be processed by RAYSHADE and used to generate a movie of the vibration. This process can, however, be very time consuming.



Jörg-Rüdiger Hill
Sun Dec 10 17:38:35 MET 2000