This program is part of Netpbm.
vidtoppm is supposed to convert Parallax XVideo JPEG to sequence of PPM files. Its source code is part of the Netpbm package for archival purposes, but it does not presently build because it requires header files that aren't in the package. If someone comes up with a use for vidtoppm, we might be able to make it work. vidtoppm was in the Berkeley MPEG encoder package from which Netpbm's ppmtompeg was derived.