After installing Open Blu-ray ripper (Version 1.20 and subsequent versions), it will automatically open the acceleration function without users' setting if the program detects that your system supports the acceleration function of HST™. If your selected video format supports H264 encoding format, you will see a black HST™ icon with a red dot added in the selected video format information bar, as shown:

If your selected video format doesn't support H264 encoding format, you will see the following picture:

If you need to close the function, please turn off the option "Use the HST technology to accelerate the encoding speed" in the setup window.