Tunelandia, thanks to you, I have discovered yet another amazing feature of Reaper.
As I said, 95% of the time you want to switch custom tunings 1, 2, 3 and 4, which are like presets inside the preset. However, sometimes you want to switch presets. Here's an example: when you are performing on stage. You can set up alt-tuner's presets to match your set list, using "Move up" and "Move down" from the preset menu. Then you can jump to the next preset with a knob or slider or pedal, rather than having to reach over to the computer.
Here's how: first download the SWS extension for Reaper from http://forum.cockos.com/showthread.php?p=1079515
. Then restart Reaper and click on Actions/Show Action list in the main menu.
In the "Filter" box, type "preset". You'll see various actions relating to effects presets. For some reason you get different results if the "Selection" box on the upper right says "Main" vs. "S&M extension".
Click on an action, perhaps "Trigger next preset of selected FX for selected tracks", to highlight it. In the lower left is a "Shortcuts for selected action" box. Click the "Add" button. You can assign a QWERTY keyboard shortcut if you want. Or you can move a pedal or knob and assign it to the action. Then choose absolute or relative. For an on/off switch, relative seems to work better.
Do the same with "Trigger previous
preset of selected FX for selected tracks", using a different keystroke or knob/pedal.
Next select the track(s) that contains alt-tuner. Open the FX rack for that track and click on alt-tuner to select it. Now use the keyboard or the pedals to move through the presets. Voila!
When you reach the beginning or the end of the preset list, it wraps around. If the pedal is also assigned a use in alt-keyswitcher, the action use will override it, as long as the track is selected. if the track isn't selected, the alt-keyswitcher use will happen. That makes this method very flexible and useful.
Another scenario for using this would be performing a song that changes from 12 keys per 8ve to 24 keys per 8ve, something which is not switchable.
There are other possible preset actions:
Trigger next/previous preset for last touched FX
Trigger next/previous preset for effect #X for selected tracks (X can be 1 through 4)
Trigger preset for effect #Y of selected track (Y can be 1 through 8 )
You may be able to do the same thing with ReaScript, but then you have to learn the scripting language. This way seems easier.
Now this is for live performance. The OP actually asked about recording, so that alt-tuner would switch presets at different points in the recorded song. One way to do this is to use marker actions. Go back to the actions list and right-click on the actions. Select "Show action IDs". Now look off to the right for the ID of your action. My example has ID #54185 (next preset) and #54186 (previous). Next insert a marker where you want the preset to change and name it !54185 or !54186. Hit the play button, and when you get to that part of the song, the preset will change.
Beware, the IDs might change in future Reaper versions, so keep an eye on that. Also be sure that the right tracks and effects are selected when you render. Also be sure the right effect preset is selected when you start. There might be a better way to do this. Maybe there is an action or a script that selects a specific preset for a specific effect on a specific track.
Marker actions are a part of the SWS extensions, not of Reaper. You can read more about them here: http://www.standingwaterstudios.com/markeractions.php