setTargetAtTime events silently dropped when startTime equals previous event's endTime

[HamptonMakes]

Description

setTargetAtTime silently drops events when the startTime equals the previous event's endTime. This is because AudioParam.cpp line 150 uses <= instead of <:

void AudioParam::setTargetAtTime(float target, double startTime, double timeConstant) {
  auto event = [target, startTime, timeConstant](AudioParam &param) {
    if (startTime <= param.getQueueEndTime()) {  // ← should be <
      return;
    }

Since setTargetAtTime sets its own endTime = startTime (the event has "infinite" conceptual duration), the getQueueEndTime() after a linearRampToValueAtTime ending at time T will be T. A subsequent setTargetAtTime starting at exactly T is then dropped because T <= T is true.

This breaks standard ADSR envelope patterns where setTargetAtTime (decay) is scheduled at exactly the moment linearRampToValueAtTime (attack) ends — a pattern used in every Web Audio ADSR tutorial.

Steps to reproduce

1. Clone the repro repo: git clone https://github.com/HamptonMakes/rnaa-settargetattime-bug
2. cd rnaa-settargetattime-bug && npm install && npx expo run:ios
3. Press "Play broken (no EPS)" — flat beep, no decay
4. Press "Play fixed (with EPS)" — tone decays naturally

The only difference is adding 0.0001 to the setTargetAtTime start time.

Or, in code:

const ac = new AudioContext();
const osc = ac.createOscillator();
const gain = ac.createGain();
osc.connect(gain);
gain.connect(ac.destination);

const now = ac.currentTime;
const attackEnd = now + 0.02;

gain.gain.setValueAtTime(0.0001, now);
gain.gain.linearRampToValueAtTime(0.3, attackEnd);
// ↓ SILENTLY DROPPED — attackEnd <= attackEnd is true
gain.gain.setTargetAtTime(0.03, attackEnd, 0.1);

osc.start(now);
osc.stop(now + 2);
// Expected: ramp up then exponential decay
// Actual: ramp up, stays at 0.3 forever (flat beep)

Snack or a link to a repository

https://github.com/HamptonMakes/rnaa-settargetattime-bug

React Native Audio API version

0.11.7

React Native version

0.81.5

Platforms

iOS

JavaScript runtime

Hermes

Workflow

Expo Dev Client

Architecture

Fabric (New Architecture)

Build type

Debug app & dev bundle

Device

iOS simulator

Device model

iPhone 16 Pro (iOS 18.6)

Acknowledgements

Yes

[closetcaiman]

Hi @HamptonMakes, thanks for well-documented issue and reproduction steps. The AudioParam interface recently underwent a comprehensive refactor regarding event handling (#995). I've verified this against the latest changes and the issue is no longer present. These will be included in the upcoming 0.12.0 release, so please stay tuned!

[closetcaiman]

Closing as fixed in 0.12.0.