I am trying to downscale a 1080i50 SDI input on decklink:3 to PAL SDI output on decklink:0 directly with melt.

Which is exactly, what I have done here successfully with the Ruby bindings: https://gist.github.com/3805493

However, I seem to not get the command line right!

That's what I had: melt -profile atsc_1080i_50 decklink:3 -consumer decklink:0 mlt_profile=dv_pal_wide

Please advise,
Markus