Your best bet to convert HDD virtual disk to VMDK is the standalone VMWare vCenter Converter. However, there might be other virtualization programs that can do the same conversion as well.
Convert Parallels Desktop or Workstation virtual hard disk to VMware virtual disk.
We found 4 software records in the database related to .hdd to .vmdk file format conversion.
Articles and other information relating to hdd into vmdk conversion:
Convert Parallels Desktop virtual machine to Vmware Workstation - Convert Parallels virtual machine format into VMware virtual machine disk with VMware vCenter Converter Standalone
Microsoft Windows software - convert hdd to vmdk on Windows
Converter for virtual machines
Convert from hdd file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned hdd to vmdk. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
A multi-platform x86 virtualization software package
Apple macOS / Mac OS X software - convert hdd to vmdk on OS X
Free open-source x86 virtualization software package for Mac
Linux/Unix software - convert hdd to vmdk on Linux
Free system virtualization platform for Linux operating system developed by Oracle