Flip CC polarity

[Saga-Daroxirel]

I was wondering if there's any way to flip the polarity of an input. I have a pedal that looks like it's registered to CC 64, but pressing the pedal is 0 and releasing it is 127, making the sound sustain when I'm not holding it. It looks like I might be able to reverse it using router rules, but I haven't been able to find enough information to figure them out. Is there any way to change it without downloading and manually compiling the core DLL with the input inverted?

[mawe42]

Hi,

the router isn't very well documented, I'm afraid. Assuming you can use the FluidSynth shell (either via telnet, command-line or config file), you can set up the router as follows.

The most important thing to understand is that clearing the router (so you can reconfigure it) means that no messages get passed anymore. To restore the default router where all messages are sent unchanged, you need to create a default route for each of the 6 event types:

router_clear

router_begin note
router_end

router_begin cc
router_end

router_begin prog
router_end

router_begin pbend
router_end

router_begin cpress
router_end

router_begin kpress
router_end

So after executing these commands, your FluidSynth should act unchanged, all messages pass as they were sent, no messages get dropped. You could also use the router_defaultl command instead of the individual default routes per event type as above. But doing it explicity makes it clearer, I think.

If you wanted to complete ignore program change events, you would simply leave out the router_begin prog, router_end bit.

Now to achieve your goal of reversing a cc, you should be able to use the following rule:

# new CC rule
router_begin cc
# match CCs on all channels, multiply channel num by 1, add 0
router_chan 0 15 1 0
# match only on CC 64 (64 - 64), multiply num by 1, add 0
router_par1 64 64 1 0
# match all values (0 - 127), multiply the value by -1 and add 127.
router_par2 0 127 -1 127
router_end

Add this rule above the empty default rule router_begin cc; router_end as shown above, then your CC should be reversed. Rules are evaluated from top to bottom, first rule wins.

So putting it all together, the following should work:

router_clear

router_begin note
router_end

router_begin cc
router_chan 0 15 1 0
router_par1 64 64 1 0
router_par2 0 127 -1 127
router_end

router_begin cc
router_end

router_begin prog
router_end

router_begin pbend
router_end

router_begin cpress
router_end

router_begin kpress
router_end

You can add all this into a text file and load the file using the -f command-line switch. Or type them in interactively via the shell.

[Saga-Daroxirel]

Thank you so much!