My Generic PSF (Portable Sound Format: PSF1, GSF) Ripping Strategy

Here I introduce my PSF ripping method.

Introduction

I assume you already know about the following things:

• What is PSF? - A format for video game music rips. In most cases, a PSF is a compressed game ROM whose non-sound stuff is removed by ripper.
• "Streamed?" "Sequenced?" What's the difference? etc. - Read PSF Frequently Asked Questions - Neill Corlett's Home Page
• What is pointer)? - For this purpose, I recommend you to learn C.
• Do I need to learn assembly? - At least you need to know basics. (for example: "What is a register?" "What is a stack?") If you already know one of assemblies, I think you can solve your problems during ripping by pinpoint googling.

Prerequisites

• Emulator (Debugger) - such as no$psx or no$gba debugger
  • It must have step execution function. (Step Into, Step Over, Run To Return)
  • It definitely should have a function that can change instructions by using assembly.
  • It should change register value. (If not available, use an external tool such as MHS.)
• IDA Pro - it will help you in reading assembly a lot. See also: IDA Pro - How To Load Game ROM
• Memory Scanner - such as Cheat Engine or Memory Hacking Software (MHS).
  • This tool is optional. It is handy when the emulator does not have built-in RAM search function.
  • It can be used to set a memory breakpoint, when the emulator does not have a memory breakpoint feature. (thankfully, nocash debuggers has the feature)

Typical structure of unaltered game

I think a game has routines like the following typically: