how can I intercept and modify program read/writes?

Say firefox writes to i开发者_如何学运维t's own history file, and I'd like to modify what it does when it does it.

How can I do that?

Similarly, say a program sends audio to the speakers/headphones. How could I intercept that signal, process it, and send it back to where it was headed? Certainly the Master Volume does something like that.

Thanks.

If you need to do some stuff with FF only, try to do with add-on API.

As for audio processing, I guess you need to use windows kernel mode.