Audio System

Free Eggbert supports two audio backends, selected at compile time via the _BASS flag in include/def.hpp.

Audio Backends

Backend	Flag	Source File	Status
DirectSound / MCI	`_BASS=FALSE` (default)	`src/sound.cpp`	Default / Active
BASS + BASSMIDI library	`_BASS=TRUE`	`src/soundbass.cpp`	Alternative

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Needs Verification

The README mentions BASS/BASSMIDI, but the current default is _BASS=FALSE (DirectSound/MCI path active). The documentation may be outdated; verify the current build configuration.

CSound Class

Header: include/sound.hpp
Implementation: src/sound.cpp (DirectSound) or src/soundbass.cpp (BASS)

The CSound class is responsible for loading and playing all audio. It is instantiated in src/blupi.cpp during application startup.

Key features:

Loads .blp sound files from gamefiles/SOUND/
Supports 3D positional audio — sounds play louder when the player is nearby
Music tracks loop and change when transitioning between regions
Vehicle sounds loop and vary in pitch based on vehicle state

DirectSound Backend (Default)

File: src/sound.cpp
Active when: _BASS=FALSE (default)

Uses the Win32 DirectSound API (via Free Direct / SDL3 abstraction on non-Windows platforms). Wraps DirectSound buffer management for loading and playback of WAV-format sound data.

WAV file loading is handled separately by src/wave.cpp (include/wave.hpp).

BASS Library Backend

File: src/soundbass.cpp
Active when: _BASS=TRUE

Uses the BASS audio library and BASSMIDI for MIDI music support. Library binaries are located in the bass/ subdirectory.

To switch to the BASS backend, change in include/def.hpp:

// Default (DirectSound/MCI):
#define _BASS FALSE

// To enable BASS library:
#define _BASS TRUE

Music

10 background music tracks: MUSIC000.BLP through MUSIC009.BLP in gamefiles/SOUND/ (uppercase extension on disk).

Music track selection is stored per-level in DescFile::music
Music stops and changes when transitioning between regions
Current music is tracked in DescSave::music

Sound Effects

93 sound effect files in gamefiles/SOUND/ (indices 0–92): SOUND000.BLP–SOUND065.BLP (uppercase) and sound066.blp–sound092.blp (lowercase). Plus a special SOUND_MOVIE=99 marker (not a real sample file).

Sound effects are organized by category. See the full Sound Effects Reference for all constants.

Sound Categories

Category	Examples
UI/Menu	`SOUND_CLICK` (0), `SOUND_ERROR` (27)
Movement / Jumping	`SOUND_JUMP0–2`, `SOUND_JUMPEND`, `SOUND_FALL`
Footsteps (surface variants)	Wood, metal, cave, slime, plastic, cheese, grass
Helicopter	`SOUND_HELICOSTART/HIGH/STOP/LOW`
Jeep	`SOUND_JEEPSTART/HIGH/STOP/LOW`
Water	`SOUND_PLOUF`, `SOUND_BLUP`, `SOUND_DROWN`
Combat / Bombs	`SOUND_BOUM`, `SOUND_GLU`, `SOUND_ELECTRO`
Power-ups	`SOUND_STARTSHIELD/STOPSHIELD`, `SOUND_STARTPOWER/STOPPOWER`
Collectibles / Goals	`SOUND_TRESOR`, `SOUND_EGG`, `SOUND_ENDOK`
Level mechanics	`SOUND_DOOR`, `SOUND_TELEPORTE`, `SOUND_BRIDGE1/2`
Character reactions	`SOUND_VERTIGO`, `SOUND_BYE`, `SOUND_MOCKERY`

Surface-Specific Footsteps

The game uses different landing/footstep sounds depending on the surface type Blupi is standing on. Each surface type has two sounds: a landing sound (JUMPEND*) and a step sound (JUMPTOC*).

Surface	JUMPEND constant	JUMPTOC constant
Default (stone)	`SOUND_JUMPEND` (3)	`SOUND_JUMPTOC` (4)
Wood	`SOUND_JUMPENDb` (78)	`SOUND_JUMPTOCb` (79)
Metal	`SOUND_JUMPENDm` (80)	`SOUND_JUMPTOCm` (81)
Cave	`SOUND_JUMPENDg` (82)	`SOUND_JUMPTOCg` (83)
Slime	`SOUND_JUMPENDo` (84)	`SOUND_JUMPTOCo` (85)
Plastic	`SOUND_JUMPENDk` (86)	`SOUND_JUMPTOCk` (87)
Cheese	`SOUND_JUMPENDf` (88)	`SOUND_JUMPTOCf` (89)
Grass	`SOUND_JUMPENDh` (90)	`SOUND_JUMPTOCh` (91)

Future Audio Work

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TODO

A potential future improvement from TODO.md: add a CMake option to select the audio backend explicitly: FREE_EGGBERT_AUDIO_BACKEND=DSOUND|BASS|STUB

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