Controlling timescale while exporting database

Hello,

I am trying to export a VCD database using the following command:

simvision -submit "database export $my_signals -format vcd -name my_vcd.vcd"

That works fine but the VCD timescale is not the desired one.

I tried the option "-timeunits ps" but that seems to work only for CSV output format.

I cannot change simvision's time_format as it is a read-only variable.

Does anyone know how to control the timescale whie exporting an existing database into VCD?

thanks