nidhi

nidhi (Sanskrit: treasure) — Sample playback engine for AGNOS.

Polyphonic sampler with key/velocity zones, ADSR envelopes, loop modes, time-stretching, SFZ/SF2 import, sample capture, and per-instrument effects.

Features

• Polyphonic engine — configurable voice stealing (Oldest/Quietest/Lowest/None), poly/mono/legato modes
• Key/velocity zones — full MIDI range mapping, round-robin groups, choke groups, velocity curves
• ADSR envelopes — per-voice and per-zone, with smooth release from any level
• Filters — SVF (LP/HP/BP/Notch) via naad, true stereo, with envelope and LFO modulation
• Loop modes — OneShot, Forward, PingPong, Reverse, LoopSustain (release exits loop), crossfade loops
• Expression — per-note pitch bend, pressure/aftertouch, brightness (CC#74), key tracking
• SFZ import — 40+ opcodes, note names, <control>/<curve>, #include, _onccN CC modulation
• SF2 import — RIFF binary parser, preset/zone extraction, PCM16 to f32
• Sample capture — record audio, auto-trim, normalize, onset detection, loop point detection
• Effects — per-instrument chain (reverb, delay, chorus, compressor, limiter) via naad
• WAV loading — io feature for file and in-memory WAV loading, plus streaming for large instruments
• Time-stretching — WSOLA and OLA algorithms (offline)
• Multi-output — per-zone bus routing
• Built on naad — shares audio synthesis primitives with the AGNOS ecosystem
• no_std compatible — works with alloc, no standard library required

Quick Start

use nidhi::prelude::*;

let sample = Sample::from_mono(vec![0.0; 44100], 44100);
let mut bank = SampleBank::new();
let id = bank.add(sample);

let zone = Zone::new(id).with_key_range(60, 60).with_root_note(60);
let mut inst = Instrument::new("piano");
inst.add_zone(zone);

let mut engine = SamplerEngine::new(16, 44100.0);
engine.set_bank(bank);
engine.set_instrument(inst);
engine.note_on(60, 100);

let (left, right) = engine.next_sample_stereo();

SFZ Import

use nidhi::prelude::*;
use nidhi::sfz;

let input = r#"
<control> default_path=samples/
<global> lovel=0 hivel=127
<group> lokey=60 hikey=72
<region> sample=piano_c4.wav pitch_keycenter=60
<region> sample=piano_c5.wav pitch_keycenter=72
"#;

let sfz_file = sfz::parse(input).unwrap();
let (instrument, sample_paths) = sfz_file.to_instrument("piano", 44100.0);

SF2 Import

use nidhi::sf2;

let bytes = std::fs::read("soundfont.sf2").unwrap();
let (presets, instruments, bank) = sf2::parse(&bytes).unwrap();

Feature Flags

Architecture

              SamplerEngine
           /     |     |     \
  Instrument  SampleBank  EffectChain  SampleRecorder
       |          |
     Zone[]    Sample[]
       |
  LoopMode, filter, LFO, pan, tune, ADSR
       |
  SfzFile / SF2 (import)    TimeStretcher (offline)

Consumers

• dhvani — Audio engine
• shruti — DAW (replaces shruti-instruments::sampler via dhvani)

License

GPL-3.0-only