can't import sdv in fcp, but hdv works, both in H264. why?

fcp 7.0.2

shot footage with a samsung HD, some in HD some in SD.
footage transferred to my macbook in mp4 (h264 codec.)

the HDV footage transfers directly in fcp.
the SDV footage does not transfer. it gives me "unknown file"

so i open my sdv in quicktime pro, and export in dv.
that works, but increases my footage size tenfold.

any suggestions?

HDV is not H.264, to my knowledge. H.264 is a codec that you should convert to something more edit friendly like pro res or dv before importing into FCP.

So, unless there is something about that camera I don't know about, you are shooting in two different formats, which is why they are being treated differently.