Samples (Audio)

allegro-ts uses the Web Audio API for sample playback.

Installation

function install_sound(digi: number, midi: number, cfg_path?: string | null): number;
function remove_sound(): void; // no-op

Creates an AudioContext and master gain node. Must be called before any sample functions.

install_sound(DIGI_AUTODETECT, MIDI_AUTODETECT, null);

Constants

Constant	Value
DIGI_AUTODETECT	-1
DIGI_NONE	0
MIDI_AUTODETECT	-1
MIDI_NONE	0
MIDI_DIGMID	1

Loading samples

async function load_sample(filename: string): Promise<SAMPLE>;

Fetches and decodes an audio file. Returns a SAMPLE object. Samples must be await-ed directly.

const explosion = await load_sample("assets/explosion.wav");

Playing samples

function play_sample(
  sample: SAMPLE,
  vol?: number, // 0–255, default 255
  pan?: number, // 0–255, default 127 (centre)
  freq?: number, // playback rate × 1000, default 1000 (1.0×)
  loop?: boolean, // default false
): void;

play_sample(explosion, 200, 127, 1000, false);
play_sample(bgMusic, 180, 127, 1000, true); // looping

Adjusting samples

function adjust_sample(sample: SAMPLE, vol: number, pan: number, freq: number, loop: boolean): void;

Modify a sample's properties while it is playing.

Stopping samples

function stop_sample(sample: SAMPLE): void;

Destroying samples

function destroy_sample(spl: SAMPLE): void;

Disconnects the audio nodes and removes the sample from the internal list.

Volume control

function set_volume(digi_volume: number, midi_volume: number): void;
function get_volume(): { digi_volume: number; midi_volume: number };

digi_volume is 0–255. The master gain node is set to digi_volume / 255.

SAMPLE structure

interface SAMPLE {
  file: string;
  source: AudioBufferSourceNode;
  gain: GainNode;
  buffer: AudioBuffer | null;
  pan: StereoPannerNode;
  type: "snd";
}