Switch Crossfades?

alexs1

I was going through the Transfer flags again for Loop Switching and wondered if something like a “Crossfade” or Blend function (/mode?) between switches would be useful or fun. I can’t conceive how it might be done in MSL, but a native Crossfade function (or mode) that happens between audio tracks (for MIDI Tracks, could just mean velocity/3rd byte) with a parameter to adjust how long the dissolve goes might be a nice touch. This could apply to NextLoop as well as Track to Track. The concept also makes for some interesting combinations in MSL, like Overdub + Crossfade. For ambient music this feels like a helpful tool for seamless transitions, and for other styles, just a fun function effect to play with.

jeff

There is a very short crossfade when switching loops to eliminate clicks when the audio content has different levels, but this can't be extended to a gradual audible crossfade. I've thought about that, but it would require some significant changes to the old code, which is really sensitive. When I get around to rewriting that, I'll consider but that's a long way off. It would be a lot easier to do with MIDI tracks.

Track-to-track cross fades are much easier to implement because they are already playing at the same time, and you would essentially just be controlling their output levels. I think a few were doing that back in the day with MOS with really long scripts that would bump the output level down, wait a few milliseconds, turn it down some more, wait, etc. until it eventually got to zero. It's not really any easier in MSL right now because it lacks a proper "iteration" statement (for i = 0 to 127 do...). That's something I've been meaning to add for a long time to make things like this easier.

jeff

Since you mention Overdub + Crossfade, if I understand this correctly, that's actually something from the EDP that exists now, and it has to do with using the Feedback control. There are several ways to do an overdub. The Overdub function combines new content with old content at the same level, unless you reduce the Feedback level. If Feedback is all the way up, then there is no reduction of the old content. Feedback can be turned down and up in real-time as you do an overdub to accomplish something like a fade out of the old content.

There is also the Substitute function from the EDP which can accomplish similar things.

If you want true crossfade where both the old content gradually fades out, and the new content gradually fades in, you would combine Overdub+Feedback with Input level control. Start with Input at 0 and gradually raise it, while Feedback starts at 127 and is gradually lowered. This is possible with scripts, but it needs iteration like I mentioned earlier to keep the scripts short.

This kind of thing is common enough that it may make sense to build in some of this without needing scripts. That does however add more knobs to the space shuttle.

alexs1

I was imagining it mainly for switching Loops, since it could then be it’s own minor mode maybe, like Mute or Record. But it sounds like it’s not as simple as function-alizing and extending the volume bump that’s already there?

jeff

Yes, it would be quite a big change to old code. The notion that tracks are only playing one loop at a time is deeply ingrained. Current crossfade works by capturing a little segment from the current loop in a temporary buffer before switching, then merging that in with the new loop after the switch. To make the crossfade longer the buffer would have to be long, maybe a second or more, and it would take some time to fill. Maybe inconsequential, I'd have to try it. But it changes the way memory management works on the switch which is a little touchy. If I were starting over, I would have multiple "play heads" in each track that could be playing things from several loops for any duration. That's actually something I'm needing to look at for buses, so maybe it can be done around the same time.