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FEU Format (Flash UI)

.feu files are the Disrupt engine's UI definition format. They are standard Flash SWF files with a 3-byte magic override.

Underlying format: The SWF body is the standard Flash format. See SWF File Format Specification (Adobe v19) for the full byte-level reference (tags, records, compressed header, etc.).

Format​

OffsetSizeValueNotes
0x003UEFSWF signature replaced (FWS → UEF)
0x0310x08SWF version (Flash 8)
0x044File length (LE u32)Same as total file size
0x08...Standard SWF bodyRectangle, frame rate, frame count, tags

The rest of the file is unmodified Flash SWF — no encryption, no compression beyond standard SWF zlib. The only difference from a valid SWF is the first 3 bytes.

Conversion​

FEU → Openable SWF​

# Method 1: sed (Linux/Mac)
sed -i '1s/UEF/FWS/' file.feu

# Method 2: dd
dd if=file.feu of=file.swf bs=1 skip=0
printf 'FWS' | dd of=file.swf bs=1 count=3 conv=notrunc 2>/dev/null

SWF → FEU (repack after editing)​

sed -i '1s/FWS/UEF/' file.swf
mv file.swf file.feu

Using hV_WD1ModdingKit (Windows)​

The modding kit swaps UEF ↔ GFX (bytes 47 46 58) instead of FWS. Both work with JPEXS. The kit is a .NET 4.7.2 VB app — does not run natively on Linux (needs Microsoft.VisualBasic runtime). Decompiled source: hV_WD1ModdingKit_decompiled/ in the Disrupt RE repo.

Using JPEXS Flash Decompiler​

JPEXS (ffdec-cli.jar v22.0.1) works on Linux natively (Java required). It accepts files with FWS, GFX, or UEF prefixes — but UEF may produce warnings. Safest to rename to .swf with FWS header first.

# Export all resources
java -jar ffdec-cli.jar -export all output_dir file.swf

# Export scripts only
java -jar ffdec-cli.jar -export script output_dir file.swf

# Export specific frame range
java -jar ffdec-cli.jar -select 1-10 -export frame output_dir file.swf

Content Structure​

FEU files contain Flash movieclips with ActionScript 2 classes. The engine loads them as UI containers.

ActionScript Class Hierarchy​

MovieClip (Flash built-in)
 └── driver.LoadableContainer
 ├── driver.gamehud.Gh_CompanionBoard
 ├── driver.gamehud.Gh_* (other HUD elements)
 └── driver.* (menu classes)

Key classes from gh_companionboard.feu:

ClassPurpose
driver.LoadableContainerBase class for all UI panels. Handles event registration, DPS IDs, visibility toggling.
driver.gamehud.Gh_CompanionBoardDigital billboard overlay. Registers digitalBoard / digitalBoardTxt DPS IDs.
fire.managers.ExtendedEventRegisterSingleton event bus. Wraps Flash's _global.ExtendedEvents for cross-panel communication.
driver.utils.EventInfoSimple event descriptor (name + delegate).

SWF Tags​

Typical FEU files contain:

  • DefineShape (16 shapes per file, SVG-exportable)
  • DefineSprite (nested animation containers, 1–58 frames each)
  • DefineEditText (text fields with font references)
  • DoAction (frame scripts, mostly stop())
  • SymbolClass (maps SWF symbols to AS2 class names)

Resource References​

FEU files reference engine resources via string paths embedded in the SWF:

UI\fonts\WD_Tech_Plain_Default.ffd — font definitions
UI\supertextures\temp_idle.bfd — texture atlases
UI\supertextures\lib_icons_greenalpha.bfd

Font names map to localization: WD_Tech_Plain (English/French/German/etc.), DFGGothicP-W5_Japanese, DFPHeiMedium-B5_ChineseTrad, mdmorrism_ps3_korean.

File Inventory​

Watch_Dogs/FEU/ (167 files)​

All .feu UI definitions. Covers: HUD elements (gh_*), menus (menu_*), phone apps (pda_*), multiplayer (mp_*), system screens (demostart, creditroll), and more.

Watch_Dogs/FEU1/ (164 files)​

Subset with minor differences. 46 files exist in FEU/ but not in FEU1/:

  • Menus: menu_start.feu, menu_shop.feu, menu_techtree.feu, menu_techtree2.feu, menu_hideout.feu
  • Phone apps: pda_alarmclock.feu, pda_alieninvasion.feu, pda_citytraveller.feu, pdajournalapp.feu, pda_musicplayer.feu, and 8 more
  • HUD: appshop.feu, citymap.feu, deadsecfieldguide.feu, gh_application.feu, gh_badge.feu, gh_battery.feu, gh_itemfeed.feu, gh_missionfeed.feu, gh_reputation.feu
  • System: journal.feu, news.feu, monitoringapp.feu, menuuplay.feu, overlay_loadouteditor.feu

WD2 Notes​

WD2 also uses .feu for its boot sequence (patch/ui/fire/bin/wd2bootsequence.feu) and UI screens. The format is identical — same UEF\x08 magic, same Flash SWF body. (Source: Ekey, XeNTaX, 2016)

Community Source​

  • Ekey (XeNTaX, 2016-12-17): .feu = Flash with UEF header
  • dvdbluray (Discord, 2026-02-08): JPEXS editing tutorial for gh_companionboard.feu
  • hardVatsuki: hV_WD1ModdingKit.exe converter (decompiled → hV_WD1ModdingKit_decompiled/)