Filtering multi-sample VCFs for low DP

Hi Team,

I have a multi-sample VCF file produced by UnifiedGenotyper. I now want to filter this file marking those variants with a low depth. However the DP entry in the info field is across all samples, and even if it were possible to assess the individual's DPs, I would then have to resolve the issue of a variant having low depth in one sample, and high in another. Any suggestions are appreciated.

Thanks for your time