Added linear gain filter

[iluvcapra]

Inspired by a comment in #217 I've added a generalized linear gain ramp filter that accepts a beginning and end gain factor and duration.

[dvdsk]

If I understand this is a more general version of #217. That is clearly something Rodio needs, nicely done! I've got some small suggestions here and there.

The main two main issues for me are:

• The behavior after the filter is done
• The name

[iluvcapra]

Hey I'm sorry I've missed these replies, I've been swamped irl but let me take a look in the next week or two.

[dvdsk]

Hey I'm sorry I've missed these replies, I've been swamped irl but let me take a look in the next week or two.

no worries, its also fine if it takes another few months. Take your time, I do that too.

[iluvcapra]

I think this is ready to go.

[dvdsk]

looking good! just a few nitpicks here and there and we can get this merged!

[iluvcapra]

I've done the review comments, one note: I've added a dependency on the "assert_float_eq" package to allow soft comparisons of floats in the case float rounding causes results to be off within the system epsilon.

[dvdsk]

love the new tests btw, very readable, very clear!

[dvdsk]

Good idea to add an example!

It might however be best to keep this one simple. Lots of user have trouble understanding how to use Rodio. Mixing multiple concepts (the new linear gain ramp and the mixing controller) could confuse them.

Maybe split off the linear gain ramp to a separate example?

[iluvcapra]

How about I just make a fadeout source?

I'd like to do an example of a linear gain ramp but I was going to wait until this was accepted and then just write an ADSR envelope source and build a new example around that.

[dvdsk]

I think we had a slight miscommunication. The example examples/mix_multiple_sources.rs changed. It was relatively simple but now contains an iterator, for_each and a queue with tx and rx. To you those are known and simple, but that is not going to be true for everyone.

It is useful to have more difficult examples in there but an example called mix_multiple_sources should in my opinion only do one thing (mix multiple sources).

[dvdsk]

fadeout source

good addition! we got fadein so why not fade out 👍

It seems implementation is trivial, and FadeIn and FadeOut are more specific and thus more readable for when someone only wants a fadein or fadeout.

[iluvcapra]

I see, I'll revert the example.

[dvdsk]

oh and you have the honor of editing the changelog 🎉 since these are two nice new api's!

(you can add them under unreleased)

[iluvcapra]

All looks good to me.

[dvdsk]

Lets get this merged!

[iluvcapra]

Thanks I'll try to do it in fewer commits next time!

[dvdsk]

Thanks I'll try to do it in fewer commits next time!

no worries! again thanks for the contribution!