Für iPhone habe ich das schon mit Erfolg benutzt:
mencoder "$file" -subcp cp1252 -sub-fuzziness 1 -subfont-autoscale 3 -subfont-blur 2 -subfont-outline 2 -aid 1 -vf scale=480:320:0:0:0.00:0.50,dsize=480:320,harddup -sws 2 -of lavf -lavfopts format=mp4 -ovc x264 -x264encopts bitrate=768:qcomp=0.6:qp_min=10:qp_max=51:qp_step=4:vbv_maxrate=1500:vbv_bufsize=2000:level_idc=30:dct_decimate:me=umh:me_range=16:keyint=250:keyint_min=25:nofast_pskip:global_header:nocabac:direct_pred=auto:nomixed_refs:trellis=1:nobrdo:nobime:nob_pyramid:nob_adapt:no8x8dct:noweight_b:bframes=0:threads=auto:frameref=1:subq=6 -af channels=2 -oac faac -faacopts br=128:mpeg=4:object=2:tns:raw -o /converted_"$file" .m4v