pnmtoy4m: invalid option -- '-' **ERROR: [pnmtoy4m] For usage hints, use option '-h'. Please take a hint.

usage: pnmtoy4m [options] [pnm-file] Reads RAW PNM/PAM image(s), and produces YUV4MPEG2 stream on stdout. Converts computer graphics R'G'B' colorspace to digital video Y'CbCr. If 'pnm-file' is not specified, reads from stdin. options: (defaults specified in []) -o n frame offset (skip n input frames) [0] -n n frame count (output n frames; 0 == all of them) [0] -r repeat last input frame -D x treat PNM images as de-interleaved fields, with: t = first-image-is-top-field b = first-image-is-bottom-field -F n:d output framerate [30000:1001 = NTSC] -A w:h output pixel aspect ratio [1:1] -I x output interlacing [from -D, or p] p = none/progressive t = top-field-first b = bottom-field-first -v n verbosity (0,1,2) [1] -B pixels are packed in BGR(A) format [RGB(A)]