FInally i was able to identify what exactly causing the issue.
IDT Audio isn't the one which installs driver for HDMI Audio. Its HD Graphics driver doing that.
Description of HD Graphics Driver
"
Description
This package provides the driver that enables the NVIDIA High-Definition (HD) Graphics in supported notebook models that are running a supported operating system. If high-definition multimedia interface (HDMI) video output is supported, this package also installs the HDMI Audio Driver."
Currently HP don't have Intel driver listed in their portal and having NVIDIA alone. I may get it resolved with Intel Driver.
Awaiting for that.
Thanks,
Anand.