JS Channel selector with crossfade? Help needed!

[amagalma]

Hello!


I have absolutely no idea about JSFX programming, so could someone help on this?
How could I make the channel selector to crossfade between one selected pair of channels and the next selected pair? Currently, it changes abruptly so there are always clicks/pops. A small crossfade of 5-10ms would solve the problem.


Thanks!

[amagalma]

Anyone who knows about JSFX programming?

[geraintluff]

So you're looking for a channel-selector effect where it always outputs on channels 1+2, but the input can smoothly switch between 1+2, 3+4, 5+6 etc. - is that correct?

If so, that's fairly straightforward - I've attached a JSFX which seems to work, should be automatable, et cetera.

Geraint

P.S. - if you want to learn JSFX yourself, we can walk through the steps it took to create this effect, but fine if you just want the effect!

EDIT - tapered the fade to reduce click even further

[amagalma]

Thank you so much Geraint!


This is exactly what I was looking for!


Thank you for offering to walk me through the steps! I mostly understand how it is constructed - I didn't know that you can define functions in any @. I thought it should be only in @init. The parts that I do not get are the DSP stuff, because I have absolutely no clue in DSP programming.
I was trying to modify the stock JS channel selector, but seeing now your code, I would never make it! :P

[geraintluff]

Originally Posted by amagalma

This is exactly what I was looking for!

Excellent.

Originally Posted by amagalma

I didn't know that you can define functions in any @. I thought it should be only in @init.

If you define them in other sections they can only be used in that section (i.e. you can't define it in @block and then use it in @sample). Whatever keeps the code tidiest, really.

Originally Posted by amagalma

I was trying to modify the stock JS channel selector, but seeing now your code, I would never make it! :P

Yeah, getting smooth transitions always seems to add way more complexity than expected, and can affect performance too if you're not careful.

I didn't have a copy of REAPER to hand when I wrote this one, so I couldn't base it on the stock one. When it's something shorter like this, starting from scratch often makes things more organised anyway, though.

[IXix]

Switcher 5 in my ReaPack

[geraintluff]

Originally Posted by IXix

Switcher 5 in my ReaPack

Looks like it has a bunch more features.

However looking at the code, "fadegain" seems to only update in @block. Doesn't this mean the gains jump every 10ms (if using a 512-sample block at 48kHz) instead of having a smooth fade?

Doesn't this still produce clicks? I can't test this because I'm not near REAPER right now, but for the default 30ms rate, I would expect this to reduce clicks by 9dB but still be audible, particularly for low-frequency inputs. Is that what you get?

[IXix]

Originally Posted by geraintluff

looking at the code, "fadegain" seems to only update in @block....Doesn't this still produce clicks?

I guess it could click with certain source material as you suggest but I never tested it that thoroughly. You're more of a DSP guy than I am so I'll take your word for it.

It sits on the master in all my projects to switch between reference tracks and it works well enough for me in that context but YMMV, as they say on the internet.

[amagalma]

Originally Posted by IXix

Switcher 5 in my ReaPack

Thanks IXix! They have more features but geraint's JS is exactly what I needed.