[step-sequencer] The slider inputs to set the envelope of the "Sweep" sound are not working as expected

[ManuLintz]

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What information was incorrect, unhelpful, or incomplete?

The two sliders to set the envelope of the "Sweep" sound are not working as expected.

What did you expect to see?

There are actually 2 issues:

1. For both inputs, the values are not updated properly. The input should update the value progressively with a 0.1 step, but it only updates to 0 or 1. The problem comes from that the value is cast into an int in the event listener callback.

const attackControl = document.querySelector("#attack");
    attackControl.addEventListener(
        "input",
        (ev) => {
             attackTime = parseInt(ev.target.value, 10);
        },
        false
);

Since their value are between 0 and 1 with a step of 0.1, the usage of "parseInt" is inadecuate.

<section class="controls">
  <label for="attack">Att</label>
  <input
    name="attack"
    id="attack"
    type="range"
    min="0"
    max="1"
    value="0.2"
    step="0.1"
  />
  <label for="release">Rel</label>
  <input
    name="release"
    id="release"
    type="range"
    min="0"
    max="1"
    value="0.5"
    step="0.1"
  />
</section>

2. The way the release input works is not correct. When the slider is set to left, the release should be 0, whereas when it's set to the right, we should be able to hear the release. Your can try for yourself here: If you set the values like this you hear a sound that is plucked:

When you set it like this you hear a longer release:

It should be the other way around

The problem comes from the implementation of the envelope:

sweepEnv.gain.linearRampToValueAtTime(
  0,
  time + attackTime - releaseTime // here it shouldn't be a "-" operator
);

I'm currently going through the Web API guide where this step sequencer is used: https://developer.mozilla.org/en-US/docs/Web/API/Web_Audio_API/Advanced_techniques

Since I identified the what causes the issue in the code I'd be happy to work on a fix + updating the doc.

Do you have any supporting links, references, or citations?

No response

Do you have anything more you want to share?

No response

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[bsmth]

Thanks for reporting this (along with the other one). Would you like to open a PR to improve it?

[ManuLintz]

Yes I'll do it, thanks for your answer !