Fixing compressor

[Mozoloa]

I've discovered that the compressor's ratio was behaving incorrectly. It was pretty much inversed in it's effect, a ratio of close to 50 was close to actually 1:1 in effect, same with close to 1 being actually close to infinity.

So I've redesigned the compressor to act in a more conventional way

I've tested it and so far it looks like it works alright, ratios are perfectly respected. More info in the code comments.

This might be app breaking for people that had implemented a hotfix on their end by reverse engineering the defective ratio tho.

[Mozoloa]

I just added softknee function to the compressor as kneeWidth arg in dB, 0 for hard knee
Inspired by this

I've tested it and it seems to work well

el.compress(1, 100, -10, 100, 12, in, in);

el.compress(1, 100, -10, 4, 6, in, in);

el.compress(1, 100, -30, 10, 24, in, in);

Sorry for the cropped out axis, but everything seem in place from the values I can see

[nick-thompson]

@Mozoloa fantastic PR thank you! A couple of quick changes if you don't mind:

• Rebase against the develop branch. I cut canary releases from develop with new features/bug fixes and then promote to main once the canary is out for a few days
• Let's introduce the soft-knee behavior as a new function el.skcompress or el.softcompress. Having both a hard and a soft option makes sense, and also this lets us avoid breaking the expected arguments to el.compress
• Then let's keep el.compress as it was but add only the ratio fix there. You're right technically that might break existing code but it feels to me like it falls more in the category of a bugfix than a breaking change.

That sound ok? That feels to me like the right to navigate non-breaking changes and bug-fixes

[Mozoloa]

All good

[nick-thompson]

Great @Mozoloa thank you again! Three more tiny things if you don't mind 🙏

[nick-thompson]

It looks like this was probably a bug leftover from me, but if you don't mind fixing it while we're here I'd appreciate it–

The type signature above doesn't present an optional props argument up front, so we can write this function signature here as

export function compress(atkMs, relMs, threshold, ratio, sidechain, xn)

and then skip the whole let children = (typeof stuff below it

[nick-thompson]

Let's do the same thing here, remove that props argument here in the type signature, and then below let's do

export function skcompress(atkMs, relMs, threshold, ratio, kneeWidth, sidechain, xn)

and skip the whole optional arg stuff

[nick-thompson]

This is my bad I think– would you mind dropping the changes to README here so that the PR only affects the compressor code? I'll fix up the README changes in a follow-up commit

[nick-thompson]

Ok got it, this will roll out with elem v3.1.0. Thank you @Mozoloa !