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sound.md

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Sound

Starting off first with the functions as the names provide context.

  • S_Init, initialises sound on game start
  • S_Start, sets up sound at level start
  • S_StartSound (basically a wrapper of S_StartSoundAtVolume)
  • S_StopSound
  • S_UpdateSounds, called every frame to ensure correct sounds are playing for state
  • S_StopChannel
  • S_SetSfxVolume

Music specific

  • S_SetMusicVolume
  • S_StartMusic
  • S_ChangeMusic
  • S_StopMusic
  • S_PauseSound, misnamed I think as it only pauses music
  • S_ResumeSound, as above

The file sounds.c contains hardcoded data about the sounds and music.

// sfxinfo_t (is sfxinfo_struct)
// name,     singularity, priority, link, pitch, volume, data, (usefulness and lumpnum missing?)
{  "pistol", false,       64,       0,    -1,    -1,     0,    },
{ "chgun",   false,       64,       &S_sfx[sfx_pistol], 150, 0, 0 },

// musicinfo_t
// name,  lumpnum, (data and handle missing?)
{ "e1m1", 0        },

OS Init part

Linux note: sound was using an ioctl in the original port, and there is no music playback. To get full sound SDL2 will be required (or something similar).

Playing Sound

S_StartSoundAtVolume is used to play a sound. The parameters are origin, sfx id, and volume.

The Sfx ID is used to fetch a sound data from the cached data, of type sfxinfo_t. This struct contains a number of things:

struct sfxinfo_struct
{
    // up to 6-character name
    char*	name;
    // Sfx singularity (only one at a time)
    int		singularity;
    // Sfx priority
    int		priority;
    // referenced sound if a link
    sfxinfo_t*	link;
    // pitch if a link
    int		pitch;
    // volume if a link
    int		volume;
    // sound data
    void*	data;
    // this is checked every second to see if sound
    // can be thrown out (if 0, then decrement, if -1,
    // then throw out, if > 0, then it is in use)
    int		usefulness;
    // lump number of sfx
    int		lumpnum;		
};

there can be multiple of a sound using a single sound file but with a different pitch.

Channels

In OG Doom the sounds are played one-per-channel.

i_sound.c

I_RegisterSong I_PlaySong S_StartSong

IsMid ConvertMus -> mus2mid Mix_LoadMUS

relationship: mobj-info -> state -> sound enum as index -> sfx priority and data array

Music:

.... ugh.

https://moddingwiki.shikadi.net/wiki/MUS_Format https://moddingwiki.shikadi.net/wiki/MID_Format

The MUS/MID combined with GENMIDI is what gave Doom it's music. The GENMIDI is used to program the OPL chip on Sound Blaster cards

https://doomwiki.org/wiki/GENMIDI https://github.com/freedoom/freedoom/blob/master/lumps/genmidi/README.adoc

Chocolate Doom does full-on OPL emulation

GUS can use SDL2 + timidity + the patch files. Will need to parse the DMXGUS lump https://www.chocolate-doom.org/wiki/index.php/GUS

S_Start controls music vs level start and selection

For the most part music selection is done via enum-name cast to int. Where:

typedef enum
{
    mus_None,
    mus_e1m1,
    mus_e1m2,
    mus_e1m3,
    mus_e1m4,
    mus_e1m5,
    mus_e1m6,
    mus_e1m7,
    mus_e1m8,
    mus_e1m9,
    mus_e2m1,
    mus_e2m2,
    mus_e2m3,
    mus_e2m4,
    mus_e2m5,
    mus_e2m6,
    mus_e2m7,
    mus_e2m8,
    mus_e2m9,
    mus_e3m1,
    mus_e3m2,
    mus_e3m3,
    mus_e3m4,
    mus_e3m5,
    mus_e3m6,
    mus_e3m7,
    mus_e3m8,
    mus_e3m9,
    }

is the index in to S_sfx [ sfxinfo_struct ], which sfxinfo_struct->name contains the lump name minus d_ appended to it.

musicinfo_t S_music[] = is in the order of the above enum.