CSound

Header: include/sound.hpp
Implementation: src/sound.cpp (DirectSound backend) and src/soundbass.cpp (BASS backend, optional)

CSound is the audio system class. It loads and plays background music and positional sound effects from .blp files in gamefiles/SOUND/. Two backends are available, selected at compile time via the _BASS flag.

Backends

To switch backends, change #define _BASS in include/def.hpp and rebuild. See Compile Flags.

DirectSound Backend

The default backend wraps DirectSound from DirectX 3. Via Free Direct / Free API, DirectSound calls are translated to SDL3_mixer.

• Loads .blp sound files via src/wave.cpp (WAV parsing)
• Supports 3D positional audio: sounds play louder when the source is near the player
• Vehicle sounds (helicopter, jeep) loop and change pitch based on movement state
• Music uses the MCI (Media Control Interface) path for MUSIC*.blp files

BASS Backend

Implemented in src/soundbass.cpp using the BASS and BASSMIDI libraries located in the bass/ subdirectory.

• MIDI music support via BASSMIDI
• Alternative to DirectSound for higher quality audio on non-Windows builds

Music

10 background music tracks are stored as MUSIC000.blp through MUSIC009.blp. The track for each level is defined in DescFile::music (0–9) and loaded when the level starts. Music stops and restarts when transitioning between regions.

Sound Effects

93 sound effect files: SOUND000.blp through SOUND092.blp. Filenames on disk have mixed case (e.g., Sound027.blp); the index directly maps to the SOUND_* constant.

See Sound Effects Reference for the complete SOUND_* constant table.

Key Methods

Full signatures from include/sound.hpp:

// Lifecycle
BOOL Create(HWND hWnd);
void SetState(BOOL bState);
BOOL GetEnable();
void Flush(int channel);       // unload one channel
void CacheAll();               // preload all sound channels
BOOL Cache(int channel, char* pFilename);

// Volume
void SetAudioVolume(int volume);
int  GetAudioVolume();
void SetMidiVolume(int volume);
int  GetMidiVolume();

// Music
BOOL PlayMusic(HWND hWnd, int music);
BOOL RestartMusic();
void SuspendMusic();
void StopMusic();
BOOL IsPlayingMusic();
void SetSuspendSkip(int nb);

// Sound effects (positional)
BOOL Play(int channel, int volume = 0, int pan = 0);
BOOL PlayImage(int channel, POINT pos, int rank = -1);  // called from CDecor/CEvent
BOOL StopSound(int channel);