FlipDCD is a small utility for reversing the endianism of binary DCD trajectory files from Charmm, and NAMD. This can be useful when running simulations on one architecture and visualizing or analyzing the results on another. FixDCD is a tiny utility to modify the header of an X-PLOR DCD file to make it readable by programs expecting Charmm DCD files, at the expense of a Timestep size value in the header.


If you have questions please send email to the author Jim Phillips, at



Same terms as NAMD license


FlipDCD provides a mechanism for converting the endianism (byte ordering) of CHARMM, X-PLOR, and NAMD DCD trajectory files so that they may be loaded by visualization and analysis programs on platforms with the opposite byte ordering of the platform on which they were originally generated. This allows one to use a Windows PC to read DCD trajectories generated on a Sun or an SGI and allows a Sun or an SGI to read trajectory files produced on a PC cluster running Linux. FlipDCD does the endianness conversion by memory mapping the DCD file with mmap(), and converting the endianism in-place. This provides a relatively high performance method to perform endianness conversion.

FlipDCD can be used to report the endian status of DCD files or to force a particular endianness without regard for the origin of the DCD files.

FlipDCD Usage:
  flipdcd [-s] [-B] [-L] file . . . 
      where "file" can be a list of files.

      The default behavior is to flip the byte ordering. Other options are:
      -s report the byte-order status of each file without changing it
      -B make/keep each file big-endian
      -L make/keep each file little-endian
      The options are mutually exclusive; the last one read is used.

FixDCD changes the header on an X-PLOR style DCD files so that they can be read by tools which expect CHARMM formatted trajectory files. As with FlipDCD, FixDCD performs the conversion in-place. This conversion is not reversible so you may wish to make a backup copy of your file(s).

FixDCD Usage:
  fixdcd filename.dcd