Crate ym2149_gist_replayer 

GIST Sound File Parser and Multi-PSG Player for YM2149

This crate provides a parser and player for GIST (Graphics, Images, Sound, Text) sound effect files, originally used on the Atari ST. GIST was developed by Dave Becker and distributed by Antic Software in the late 1980s.

Overview

GIST sound effects are 112-byte definitions that describe complex synthesizer patches with ADSR-style envelopes for volume, frequency, and noise, plus LFO modulation for vibrato, tremolo, and noise effects.

The driver processes sounds at 200 Hz (matching the Atari ST Timer C rate) and supports up to 3 simultaneous voices on a single YM2149 PSG chip.

Quick Start

For simple playback, use GistPlayer:

use ym2149_gist_replayer::{GistPlayer, GistSound};

// Load and play a sound effect
let sound = GistSound::load("effect.snd").unwrap();
let mut player = GistPlayer::new();

player.play_sound(&sound, None, None);

// Generate audio samples
while player.is_playing() {
    let samples = player.generate_samples(882); // ~20ms at 44100 Hz
    // Send samples to audio output...
}

Low-Level API

For more control, use GistDriver directly with a Ym2149 chip:

use ym2149::Ym2149;
use ym2149_gist_replayer::{GistDriver, GistSound, TICK_RATE};

let sound = GistSound::load("effect.snd").unwrap();
let mut chip = Ym2149::new();
let mut driver = GistDriver::new();

driver.snd_on(&mut chip, &sound, None, None, -1, i16::MAX - 1);

// In your audio loop, call tick() at 200 Hz
while driver.is_playing() {
    driver.tick(&mut chip);
    // Generate samples from chip...
}

Sound Structure

Each GIST sound contains:

• Duration: How long the sound plays in ticks (200 Hz)
• Tone parameters: Initial frequency, envelope, and LFO settings
• Noise parameters: Initial noise frequency, envelope, and LFO settings
• Volume envelope: ADSR-style envelope with LFO modulation

Values use 16.16 fixed-point format for smooth envelope transitions.

Structs

GistDriver

GistMetadata

Metadata for GIST sound effects.

GistPlayer

High-level GIST sound effect player.

GistSound

GIST Sound Definition

Enums

PlaybackState

Playback state for chiptune players.

Constants

DEFAULT_SAMPLE_RATE

Standard audio sample rate (44.1 kHz CD quality).

TICK_RATE

GIST sound driver tick rate in Hz. The driver processes all voices at this rate.

Traits

ChiptunePlayer

Unified player interface for chiptune formats.

ChiptunePlayerBase

Object-safe base trait for chiptune players.