man ppmtoeyuv (Commandes) - convert a portable pixmap into a Berkeley YUV file
NAME
ppmtoeyuv - convert a portable pixmap into a Berkeley YUV file
SYNOPSIS
ppmtoeyuv [ppmfile]
DESCRIPTION
Reads a portable pixmap as input. Produces a Berkeley Encoder YUV (not the same as Abekas YUV) file on the Standard Output file.
With no argument, takes input from Standard Input. Otherwise, ppmfile is the file specification of the input file.
ppmtoeyuv handles multi-image PPM input streams, outputting consecutive eyuv images. There must be at least one image, though.