HomuraHime-Mods/docs/FMOD_MODIFICATION_GUIDE_PHASE3.md

Phase 3: FMOD Bank Modifications Guide

Overview

This phase covers extracting and modifying FMOD audio banks using FMOD Studio and AssetRipper.

Prerequisites:

• FMOD Studio 2.02.x installed (free from fmod.com)
• AssetRipper installed
• Game installed at: C:\apps\steam\steamapps\common\Homura Hime\

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Step 1: Extract FMOD Banks with AssetRipper

1.1 Launch AssetRipper

Location: C:\projects\HomuraHime-Mods\tools\AssetRipper\AssetRipper.exe

1.2 Load HomuraHime

1. Click File → Load (or drag folder)
2. Navigate to: C:\apps\steam\steamapps\common\Homura Hime\HomuraHime_Data\
3. Select the folder and click Open

1.3 Export Settings

1. Click File → Export
2. Choose Resources (not Asset Directories)
3. Set output path: C:\projects\HomuraHime-Mods\extracted_assets\

1.4 Locate FMOD Banks

After export, find banks at:

C:\projects\HomuraHime-Mods\extracted_assets\StreamingAssets\FMOD\Desktop\

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Step 2: Open Banks in FMOD Studio

2.1 Launch FMOD Studio

Location: C:\Program Files\FMOD Studio\FMOD Studio.exe

2.2 Open Project (or Banks Directly)

Option A: If you have the original FMOD project (unlikely for commercial game):

• File → Open Project → Select .fprojekt file

Option B: Open bank files directly:

• File → Open Bank → Select Master.bank from the extracted folder
• FMOD will automatically load related banks

2.3 Bank Organization

In FMOD Studio, you'll see:

• Events: Sound events (grouped by banks: SFX, Ambience, BGM, Voice)
• Audio Tables: Banks, VCA groups, snapshots
• Mixer: Master output with routing

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Step 3: Voice Limit Improvements

3.1 Find Problematic Events

Search for events with high polyphony:

1. In FMOD Studio, select SFX.bank in the Banks panel
2. Look at event properties in the Inspector
3. Check Maximum Instances ( polyphony)

3.2 Adjust Voice Aging

For events that cause glitches:

1. Right-click event → Properties
2. Go to Voices tab
3. Settings to adjust:

   Max Instances: 16 (from default 32)
   Voice Stealing: Steal Oldest
   Voice Aging: 1.0 seconds (faster cleanup)
   

3.3 Key Events to Check

In SFX.bank:

• Attack impact sounds (often triggered rapidly)
• Footstep/landing sounds (PreLoad banks)
• Enemy alert/warning sounds
• UI feedback sounds

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Step 4: Audio Ducking Improvements

4.1 Access Mixer

1. Click Mixer tab in FMOD Studio
2. You'll see VCA groups and the Master bus

4.2 Configure Ducking Groups

Look for:

• Speech (Voice channel)
• SFX (Sound effects)
• Music (BGM)

4.3 Adjust Ducking Parameters

For the Master or speech bus:

1. Right-click → Add Effect → Duck
2. Configure:

   Threshold: -20 dB (triggers at this volume)
   Rate: 100% (fade speed)
   Attack: 10 ms (fast attack)
   Release: 200 ms (slower release)
   

4.4 Create/Modify Snapshots

Snapshots control ducking behavior:

1. In the Audio Tables panel, select Snapshots
2. Find existing battle/start snapshots
3. Modify duck amounts:

   Music Duck Amount: -12 dB (not too aggressive)
   SFX Duck Amount: -6 dB
   

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Step 5: Enemy Behavior Indicator Improvements

5.1 Locate Enemy Audio Events

In Ambience.bank:

• enemy_idle_loop - Enemy ambient when not engaged
• enemy_alert - Enemy noticing player
• enemy_chase - Enemy pursuing

In SFX.bank:

• Attack indicator sounds
• Danger/warning cues

5.2 Increase Volume on Behavior Sounds

1. Find enemy-related events
2. Select the event → Inspector
3. Volume slider: Increase by 3-6 dB

   Before: 0.0 dB
   After: +3.0 dB to +6.0 dB
   

5.3 Add Pitch Variation

For more distinct enemy states:

1. Select enemy event (e.g., alert)
2. Add Pitch automation or randomizer
3. Set variation:

   Center: 0 semitones
   Range: ±2 semitones random
   

5.4 Add 3D Positioning

For directional audio:

1. Select event → 3D checkbox
2. Configure:

   Min Distance: 1.0 m
   Max Distance: 20.0 m
   Rolloff: Linear
   

3. This makes enemy sounds come from their position

5.5 Create State Layers

For distinct enemy behavior indicators, add parameters:

1. Right-click event → Add Parameter
2. Name: EnemyState
3. Values: 0=Idle, 1=Alert, 2=Attacking
4. Add automation for volume/effect per state

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Step 6: Reimport Modified Banks

6.1 Save Changes

1. In FMOD Studio: File → Save
2. Banks will auto-update in the project folder

6.2 Export Banks

1. File → Export → banks
2. Choose the extracted Desktop\ folder
3. Confirm overwrite

6.3 Verify Export

Check that modified .bank files have new timestamps.

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Step 7: Backup Original Banks

CRITICAL - Before testing:

mkdir "C:\projects\HomuraHime-Mods\backup_banks_original"
copy "C:\projects\HomuraHime-Mods\extracted_assets\StreamingAssets\FMOD\Desktop\*.bank"
      "C:\projects\HomuraHime-Mods\backup_banks_original\"

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File Locations Reference

Game Banks (Read-Only Backup)

C:\apps\steam\steamapps\common\Homura Hime\HomuraHime_Data\StreamingAssets\FMOD\Desktop\

Extracted for Editing

C:\projects\HomuraHime-Mods\extracted_assets\StreamingAssets\FMOD\Desktop\

Modified Banks (Copy to Game)

C:\projects\HomuraHime-Mods\modified_banks\FMOD\Desktop\

Backup Original

C:\projects\HomuraHime-Mods\backup_banks_original\

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Banks to Prioritize

Priority	Bank	Reason
HIGH	SFX.bank	Contains attack/impact sounds that glitch
HIGH	Ambience.bank	Enemy behavior indicators
MEDIUM	Master.bank	Contains mixer and routing
MEDIUM	Voice.bank	May need voice limit adjustments
LOW	BGM*.bank	Background music - less critical

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Verification Checklist

After modifications:

• Banks export successfully from FMOD Studio
• New bank files are in modified_banks\
• Original banks backed up
• Test game loads without FMOD errors
• Audio glitches reduced in combat
• Enemy indicators more audible

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Next Steps

After completing FMOD modifications:

• Phase 4: BepInEx plugin deployment
• Phase 5: Testing and iteration
• Phase 6: Distribution