483 lines
15 KiB
C
483 lines
15 KiB
C
/* TODO: Cap max sounds playing. */
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/* Terminology:
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*
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* `Sample`: Once "PCM" data point representing the smallest unit of audio available for a single channel at a point in time.
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* Examples:
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* - Single 32 bit float output by mixer and consumed by playback API, that the API interprets as a sound sample for a single channel
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* - Single 16 bit integer output by audio file decoder, that may represent a mono sound sample
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*
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* `Frame`: Represents a single data point of audio for all audio channels at a point in time.
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* Examples:
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* - Single 16 bit integer output by audio file decoder representing one mono sound sample
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* - 2 16 bit integer samples output by audio file decoder representing two sound samples, one sample for each audio channel
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* - 2 32 bit float samples output by mixer and consumed by playback API, one sample for each audio channel
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*/
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MIX_SharedState M_shared_state = ZI;
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////////////////////////////////////////////////////////////
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//~ Startup
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void MIX_Startup(void)
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{
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__prof;
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MIX_SharedState *g = &M_shared_state;
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g->track_arena = AcquireArena(Gibi(64));
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g->listener_pos = VEC2(0, 0);
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g->listener_dir = VEC2(0, -1);
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}
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////////////////////////////////////////////////////////////
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//~ Track
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MIX_Handle MIX_HandleFromTrack(MIX_Track *track)
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{
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MIX_Handle result = ZI;
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result.gen = track->gen;
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result.data = track;
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return result;
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}
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MIX_Track *MIX_TrackFromHandle(MIX_Handle handle)
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{
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MIX_Track *track = (MIX_Track *)handle.data;
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if (track && track->gen == handle.gen)
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{
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return track;
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}
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else
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{
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return 0;
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}
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}
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MIX_Track *MIX_AcquireTrackLocked(Lock *lock, SND_Sound *sound)
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{
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MIX_SharedState *g = &M_shared_state;
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AssertLockedE(lock, &g->mutex);
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LAX lock;
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MIX_Track *track = 0;
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if (g->track_first_free)
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{
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/* Take from free list */
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track = g->track_first_free;
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MIX_Track *next_free = track->next;
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g->track_first_free = next_free;
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if (next_free)
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{
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next_free->prev = 0;
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}
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*track = (MIX_Track) { .gen = track->gen + 1 };
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}
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else
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{
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/* Acquire new */
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track = PushStruct(g->track_arena, MIX_Track);
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track->gen = 1;
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}
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track->sound = sound;
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track->mix.source = sound;
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track->mix.track_handle = MIX_HandleFromTrack(track);
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/* Append to playing list */
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MIX_Track *prev = g->track_last_playing;
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if (prev)
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{
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prev->next = track;
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}
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else
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{
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g->track_first_playing = track;
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}
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g->track_last_playing = track;
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track->prev = prev;
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++g->track_playing_count;
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return track;
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}
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void MIX_ReleaseTrackLocked(Lock *lock, MIX_Track *track)
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{
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MIX_SharedState *g = &M_shared_state;
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AssertLockedE(lock, &g->mutex);
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LAX lock;
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/* Remove from playing list */
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MIX_Track *prev = track->prev;
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MIX_Track *next = track->next;
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if (prev)
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{
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prev->next = next;
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}
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else
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{
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/* Track was first in list */
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g->track_first_playing = next;
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}
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if (next)
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{
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next->prev = prev;
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}
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else
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{
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/* Track was last in list */
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g->track_last_playing = prev;
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}
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--g->track_playing_count;
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++track->gen;
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/* Add to free list */
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track->prev = 0;
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track->next = g->track_first_free;
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if (g->track_first_free)
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{
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g->track_first_free->prev = track;
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}
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g->track_first_free = track;
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}
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////////////////////////////////////////////////////////////
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//~ Mixer control
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/* TODO: Rework interface to be command based instead of directly modifying tracks. */
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MIX_Handle MIX_PlaySound(SND_Sound *sound)
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{
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return MIX_PlaySoundEx(sound, M_TRACKDESC());
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}
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MIX_Handle MIX_PlaySoundEx(SND_Sound *sound, MIX_TrackDesc desc)
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{
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MIX_SharedState *g = &M_shared_state;
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MIX_Track *track;
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{
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Lock lock = LockE(&g->mutex);
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{
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track = MIX_AcquireTrackLocked(&lock, sound);
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track->desc = desc;
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}
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Unlock(&lock);
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}
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return MIX_HandleFromTrack(track);
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}
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/* NOTE: This is quite inefficient. */
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MIX_TrackDesc MIX_TrackDescFromHandle(MIX_Handle handle)
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{
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MIX_SharedState *g = &M_shared_state;
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MIX_TrackDesc result = ZI;
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MIX_Track *track = MIX_TrackFromHandle(handle);
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if (track)
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{
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/* TODO: Only lock mutex on track itself or something */
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Lock lock = LockE(&g->mutex);
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{
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/* Confirm handle is still valid now that we're locked */
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track = MIX_TrackFromHandle(handle);
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if (track)
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{
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result = track->desc;
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}
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}
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Unlock(&lock);
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}
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return result;
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}
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/* NOTE: This is quite inefficient. */
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void MIX_UpdateTrack(MIX_Handle handle, MIX_TrackDesc desc)
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{
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MIX_SharedState *g = &M_shared_state;
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MIX_Track *track = MIX_TrackFromHandle(handle);
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if (track)
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{
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/* TODO: Only lock mutex on track itself or something */
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Lock lock = LockE(&g->mutex);
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{
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/* Confirm handle is still valid now that we're locked */
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track = MIX_TrackFromHandle(handle);
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if (track)
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{
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track->desc = desc;
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}
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}
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Unlock(&lock);
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}
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}
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void MIX_UpdateListener(Vec2 pos, Vec2 dir)
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{
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MIX_SharedState *g = &M_shared_state;
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Lock lock = LockE(&g->mutex);
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{
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g->listener_pos = pos;
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g->listener_dir = NormVec2(dir);
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}
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Unlock(&lock);
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}
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////////////////////////////////////////////////////////////
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//~ Mix
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i16 MIX_SampleSound(SND_Sound *sound, u64 sample_pos, b32 wrap)
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{
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if (wrap)
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{
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return sound->samples[sample_pos % sound->samples_count];
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}
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else if (sample_pos < sound->samples_count)
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{
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return sound->samples[sample_pos];
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}
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else
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{
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return 0;
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}
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}
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/* To be called once per audio playback interval */
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MIX_PcmF32 MIX_MixAllTracks(Arena *arena, u64 frame_count)
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{
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__prof;
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TempArena scratch = BeginScratch(arena);
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MIX_SharedState *g = &M_shared_state;
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MIX_PcmF32 result = ZI;
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result.count = frame_count * 2;
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result.samples = PushStructs(arena, f32, result.count);
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Vec2 listener_pos = VEC2(0, 0);
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Vec2 listener_dir = VEC2(0, 0);
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//- Create temp mix array
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MIX_MixData **mixes = 0;
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u64 mixes_count = 0;
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{
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Lock lock = LockE(&g->mutex);
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/* Read listener info */
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listener_pos = g->listener_pos;
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listener_dir = g->listener_dir;
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/* Update & read mixes */
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mixes = PushStructsNoZero(scratch.arena, MIX_MixData *, g->track_playing_count);
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for (MIX_Track *track = g->track_first_playing; track; track = track->next)
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{
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__profn("Prepare track");
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MIX_MixData *mix = &track->mix;
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mix->desc = track->desc;
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mixes[mixes_count++] = mix;
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}
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Unlock(&lock);
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}
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//- Process mix data
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for (u64 mix_index = 0; mix_index < mixes_count; ++mix_index)
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{
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__profn("Mix track");
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MIX_MixData *mix = mixes[mix_index];
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if (mix->source->samples_count <= 0)
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{
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/* Skip empty sounds */
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continue;
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}
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SND_Sound *source = mix->source;
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MIX_TrackDesc desc = mix->desc;
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MIX_EffectData *effect_data = &mix->effect_data;
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b32 source_is_stereo = source->flags & SND_SoundFlag_Stereo;
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f32 speed = MaxF32(0, desc.speed);
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//- Determine sample range
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u64 source_samples_count = 0;
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if (source_is_stereo)
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{
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source_samples_count = frame_count * 2;
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/* Round <samples_count * speed> to nearest frame boundary (nearest multiple of 2) */
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source_samples_count = (u64)CeilF32ToI32((f32)source_samples_count * speed);
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source_samples_count &= ~1;
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}
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else
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{
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source_samples_count = frame_count;
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/* Round <samples_count * speed> to nearest sample */
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source_samples_count = (u64)RoundF32ToI32((f32)source_samples_count * speed);
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}
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u64 source_sample_pos_start = mix->source_pos;
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u64 source_sample_pos_end = source_sample_pos_start + source_samples_count;
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if (source_sample_pos_end >= source->samples_count)
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{
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if (desc.looping)
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{
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source_sample_pos_end = source_sample_pos_end % source->samples_count;
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}
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else
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{
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source_sample_pos_end = source->samples_count;
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mix->track_finished = 1;
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}
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}
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u64 source_frames_count = source_is_stereo ? source_samples_count / 2 : source_samples_count;
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u64 source_frame_pos_start = source_is_stereo ? source_sample_pos_start / 2 : source_sample_pos_start;
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mix->source_pos = source_sample_pos_end;
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MIX_PcmF32 mix_pcm = {
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.count = result.count,
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.samples = PushStructs(scratch.arena, f32, result.count)
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};
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//- Resample
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/* Transform 16 bit source -> 32 bit stereo at output duration */
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{
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__profn("Resample");
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f32 *out_samples = mix_pcm.samples;
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u64 out_frames_count = mix_pcm.count / 2;
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/* TODO: Fast path for 1:1 copy when speed = 1.0? */
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/* TODO: Optimize */
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if (source_is_stereo)
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{
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/* 16 bit Stereo -> 32 bit Stereo */
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for (u64 out_frame_pos = 0; out_frame_pos < out_frames_count; ++out_frame_pos)
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{
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f32 in_frame_pos_exact = source_frame_pos_start + (((f32)out_frame_pos / (f32)out_frames_count) * (f32)source_frames_count);
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u32 in_frame_pos_prev = FloorF32ToI32(in_frame_pos_exact);
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u32 in_frame_pos_next = CeilF32ToI32(in_frame_pos_exact);
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/* Sample source */
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f32 sample1_prev = MIX_SampleSound(source, (in_frame_pos_prev * 2) + 0, desc.looping) * (1.f / 32768.f);
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f32 sample1_next = MIX_SampleSound(source, (in_frame_pos_next * 2) + 0, desc.looping) * (1.f / 32768.f);
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f32 sample2_prev = MIX_SampleSound(source, (in_frame_pos_prev * 2) + 1, desc.looping) * (1.f / 32768.f);
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f32 sample2_next = MIX_SampleSound(source, (in_frame_pos_next * 2) + 1, desc.looping) * (1.f / 32768.f);
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/* Lerp */
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f32 t = in_frame_pos_exact - (f32)in_frame_pos_prev;
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f32 sample1 = LerpF32(sample1_prev, sample1_next, t);
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f32 sample2 = LerpF32(sample2_prev, sample2_next, t);
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out_samples[(out_frame_pos * 2) + 0] += sample1;
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out_samples[(out_frame_pos * 2) + 1] += sample2;
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}
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}
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else
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{
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/* 16 bit Mono -> 32 bit Stereo */
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for (u64 out_frame_pos = 0; out_frame_pos < out_frames_count; ++out_frame_pos)
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{
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f32 in_frame_pos_exact = source_frame_pos_start + (((f32)out_frame_pos / (f32)out_frames_count) * (f32)source_frames_count);
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u32 in_frame_pos_prev = FloorF32ToI32(in_frame_pos_exact);
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u32 in_frame_pos_next = CeilF32ToI32(in_frame_pos_exact);
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/* Sample source */
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f32 sample_prev = MIX_SampleSound(source, in_frame_pos_prev, desc.looping) * (1.f / 32768.f);
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f32 sample_next = MIX_SampleSound(source, in_frame_pos_next, desc.looping) * (1.f / 32768.f);
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/* Lerp */
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f32 t = (f32)in_frame_pos_exact - in_frame_pos_prev;
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f32 sample = LerpF32(sample_prev, sample_next, t);
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out_samples[(out_frame_pos * 2) + 0] += sample;
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out_samples[(out_frame_pos * 2) + 1] += sample;
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}
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}
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}
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//- Spatialize
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if (desc.flags & MIX_TrackFlag_Spatialize)
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{
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__profn("Spatialize");
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/* Algorithm constants */
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const f32 rolloff_height = 1.2f;
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const f32 rolloff_scale = 6.0f;
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const f32 pan_scale = 0.75;
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Vec2 pos = desc.pos;
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/* If sound pos = listener pos, pretend sound is close in front of listener. */
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if (EqVec2(listener_pos, pos))
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{
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pos = AddVec2(listener_pos, MulVec2(listener_dir, 0.001f));
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}
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Vec2 sound_rel = SubVec2(pos, listener_pos);
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Vec2 sound_rel_dir = NormVec2(sound_rel);
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/* Calculate volume */
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f32 volume_start = effect_data->spatial_volume;
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f32 volume_end;
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{
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/* https://www.desmos.com/calculator/c2h941hobz
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* h = `rolloff_height`
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* s = `rolloff_scale`
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*/
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f32 dist = Vec2Len(sound_rel);
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f32 v = (dist / rolloff_scale) + 1.0f;
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volume_end = rolloff_height * (1.0f / (v * v));
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}
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effect_data->spatial_volume = volume_end;
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/* Calculate pan */
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f32 pan_start = effect_data->spatial_pan;
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f32 pan_end = WedgeVec2(listener_dir, sound_rel_dir) * pan_scale;
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effect_data->spatial_pan = pan_end;
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/* Spatialize samples */
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for (u64 frame_pos = 0; frame_pos < frame_count; ++frame_pos)
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{
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f32 t = (f32)frame_pos / (f32)(frame_count - 1);
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f32 volume = LerpF32(volume_start, volume_end, t);
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f32 pan = LerpF32(pan_start, pan_end, t);
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u64 sample1_index = frame_pos * 2;
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u64 sample2_index = sample1_index + 1;
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f32 sample_mono = ((mix_pcm.samples[sample1_index + 0] / 2.0f) + (mix_pcm.samples[sample2_index] / 2.0f)) * volume;
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mix_pcm.samples[sample1_index] = sample_mono * (1.0f - pan);
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mix_pcm.samples[sample2_index] = sample_mono * (1.0f + pan);
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}
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}
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//- Mix into result
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for (u64 i = 0; i < mix_pcm.count; ++i)
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{
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result.samples[i] += mix_pcm.samples[i] * desc.volume;
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}
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}
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//- Update track effect data
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{
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__profn("Update track effect data");
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Lock lock = LockE(&g->mutex);
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for (u64 i = 0; i < mixes_count; ++i)
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{
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MIX_MixData *mix = mixes[i];
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MIX_Track *track = MIX_TrackFromHandle(mix->track_handle);
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if (track)
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{
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if (mix->track_finished)
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{
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/* Release finished tracks */
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MIX_ReleaseTrackLocked(&lock, track);
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}
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}
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}
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Unlock(&lock);
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}
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EndScratch(scratch);
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return result;
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}
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