How to change certain bytes in huge file in Inno Setup?

Question

I am trying to replace a file's contents. The file is a huge binary file (500 MB).

I need to change some of bytes in it with my Inno Setup script.

How can I do it?

Here is the screenshot of my file's hex code that I want to change.

Here is the files:

I want to make the right side file just like the one on the left side.

Answer 1

Start here: Writing binary file in Inno Setup.

And you need to do two changes:

• Open an existing file for writing, instead of creating a new one:

  Stream := TFileStream.Create(FileName, fmOpenReadWrite);
  

• Seek to the desired position before writing the data:

  Stream.Seek($217F6DF1, soFromBeginning)
  Stream.WriteBuffer(Buffer, Size);