A big Envelope plugin update in 7.2.0

[katspaugh]

Heads up, a major update for the Envelope plugin will be released in 7.2.0.

⚠️ It has a new API for defining volume ramps, so please update your applications accordingly. ⚠️

New features

• It can now have an arbitrary number of draggable points that control volume changes
• You can drag the entire polyline to change all points at once
• You can double-click anywhere on the waveform to create a new point at that position
• You can drag points out of the waveform to remove them

Preview: https://envelope.wavesurfer-js.pages.dev/#envelope.js

Implementation changes

I've moved away from using WebAudio for scheduled gain ramps and instead calculate volume changes over time in JS and set the media element volume accordingly. This allows for seamless volume changes when changing the audio position and doesn't require a user gesture for playback.

Screenshots