Using a Boss GT-10 with PiPedal / MIDI tap tempo?

[davidofchatham]

Thanks to @rerdavies for this amazing project. I've been wanting to try NAM for a while, but just saw the PiPedal introduction in the NAM Facebook group recently. At almost the same time, providentially, a friend asked for help getting a newer PC running and is letting me have his old hardware. I've already installed PiPedal on a spare drive to test it out with that old system, and it works!

I have a Boss GT-10 MFX, which has USB, and somewhat amazingly, both audio and MIDI seem to be fully supported on Ubuntu. But I'm not sure if I'll be able to use it very effectively as a controller.

Patch changes: I was hoping that I would be able to map patches on the GT-10 to banks/presets/snapshots in PiPedal, so that I could have blank (or partial) patches on the GT-10 which I name to correspond with my PiPedal configuration and use the GT-10 as my primary controller. Unfortunately, the GT-10's MIDI output isn't recognized by PiPedal.

According to the GT-10 Manual (excerpted patch number map page and MIDI implementation page), it seems the patch change MIDI output consists of a two-part bank code on CC #0 and #32 and a program number. I thought I might be able to modify it with a x42 MIDI mapping plugin, but that doesn't seem to be recognized by PiPedal (user error is definitely a possibility, but I have installed another plugin successfully).

Is there any way I can have PiPedal recognize the GT-10's patch change output?

Tap tempo: One of the main reasons I picked the GT-10 back in the day (2008?) was that it allowed tap tempo–based timing for all its time-related effects. PiPedal does recognize the output from the GT-10's assignable control pedals, but I can't figure out how to map to the system (PiPedal) MIDI clock. What am I missing?

Thank you!

[rerdavies]

The GT-10: I know it well! :-)

PiPedal's midi support is pretty lightweight at present. You can:

• Change presets and banks, by sending bank select and program select messages.

• Bind notes and controllers to plugin controls using MIDI bindings.

• A handful of system-related generic MIDI bindings (next/prev program, next/prev bank(?), snapshot selection)

So, you should be able to track program changes from the GT-10, as long as the bank is 0 (or small-ish). PiPedal does support multiple banks. They are numbered sequentially, starting at zero, in the order they appear in the bank selection UI. I'm not sure what happens if the bank number is out of range. I would imagine that the MIDI program selection should still work (as long as the program # is in range.

And what you cannot do is map program/bank messages to plugin controls.

There is currently no routing of MIDI messages, and plugins do not currently receive direct MIDI messages. Other things it does not do:

• Handle MIDI time clock message.
• No handling of RPN's and NPRNs. Or aftertouch.
• Provide fine-grained sample-accuate delivery of MIDI mssages.

Definitely in the development backlog. But that's the current state of things, I'm afraid.

MIDI-based Tap-tempo support, however, is a coming soon feature. I can't commit to a date, but it is in the current development backlog with a priority that means it will get done soon. Browser UIs, unfortunately, may have too much jitter to do usable tap tempo from the Web UI (but I'll give it a try). But tap tempo using MIDI controls will definitely work (soon). Probably via midi bindings, for any arbitrary LV2 plugin control that declares that its values are measured in units of time. At least that's the plan.

AND... Pipedal does it's best to ignore MIDI-only plugins, in case you can't figure out why the x64 Midi Mapper control doesn't show up.

[rerdavies]

Btw, I THINK you'll find that the GT-10 "Bank +/-" switches don't actually send bank changes. And that the "bank" that comes after 00/00, 00/01, 00/02, 00/03 (on the 4 foot switches) is actually 00/04 (bank 0, program 4), 00/05, 00/06, 00/07 etc.

So your GT-10 User bank maps very nicely onto the Pipedal default bank. Provided you're willing to arrange your GT-10 User bank to match. With the word "nicely" being used in a very broad and imprecise way. :-P

I didn't think it was a very useful feature when I owned a GT-10. It works. But it is awkward.

[davidofchatham]

My imprecise recollection was that it was disappointing both as a general purpose midi controller, and that there was something annoying about the USB audio implementation. (Not being able to disable the direct path signal? Maybe? It's been a while since I had one, unfortunately).

"Direct monitor" always resets to On when the device is powered on. That might be what you're remembering.

Out of curiosity, which plugins are you seeing in the MIDI Plugin category?

I'll have to check (all the hardware is at my office right now). I've installed a couple of the your recommended plugin packs, but I'm not sure whether anything is showing up there yet.

Btw, I THINK you'll find that the GT-10 "Bank +/-" switches don't actually send bank changes. And that the "bank" that comes after 00/00, 00/01, 00/02, 00/03 (on the 4 foot switches) is actually 00/04 (bank 0, program 4), 00/05, 00/06, 00/07 etc.

So your GT-10 User bank maps very nicely onto the Pipedal default bank. Provided you're willing to arrange your GT-10 User bank to match. With the word "nicely" being used in a very broad and imprecise way. :-P

I think you're correct, with the caveat that (according to the manual) the patch/program numbers start at 1 rather than 0, unlike the bank numbers. I'll have to see if PiPedal will respond to the patch switching. That should work once I switch to the "performance" view?

It sounds like the only viable option for snapshot switching will be a separate controller — am I right? [Edit:] Or could the program change messages be assigned to snapshots rather than to presets?

[davidofchatham]

I feel your pain. I think there IS some mention of that in the user documentation (under which LV2 plugins can I use with PiPedal). Which is a half-hearted excuse given that I never read the user manual, and don't serious expect PIpedal users to do so either. It's hard to know where else to document that kind of restriction. I'll give some thought as to whether I can do better. Maybe a warning dialog with a "[ ] Don't ever show me this message ever again" checkbox. :-/

As an FYI, not a "gotcha," the LV2 plugin support notes state, "Must not be a MIDI instrument." Maybe a mapper technically is an instrument, but I read right past that, not thinking of it that way.

[davidofchatham]

Out of curiosity, which plugins are you seeing in the MIDI Plugin category?

None! So I guess that's good. 🙂

[davidofchatham]

I'll have to see if PiPedal will respond to the patch switching. That should work once I switch to the "performance" view?

Yup, that works!

Or could the program change messages be assigned to snapshots rather than to presets?

What do you think about this idea? (I'd be happy to switch presets between songs other ways, e.g. by switching to manual mode on the GT-10 and using the bank pedals to increment the patch — I just tried this and it works — or by using a phone/tablet.)

Too rare a use case?

[rerdavies]

:-) Too rare a use case., I'm afraid. And only there to accomodate a device that ... is less flexible than it really should be. :-/

A non-obvious feature that I don't really promote. But it might be of interest to you. It's there because it was extra effort to NOT do it. And it is a halfway useful feature in its own right If you have patches with identical structure, you actually get the same treatment that snapshots get: plugins do NOT get reloaded; preset switches are instantaneous; and you reverb tails don't get interrupted. To get that behaviour, you must not move or change any of the plugins in the pedalboard. Just save an existing preset as a new preset (and then modify the controls however you see fit).

So if you're after snapshot BEHAVIOUR (without the convenience of big fat buttons on the performance view), you can get that from an Up/Down program select.

OR, you could arrange your presets in sets of four, and get the EQUIVALENT of four snapshots per song. And then use your GT-10 "bank" up/down footswitches to move to the next song/set of four presets.

A bit hacky and messy, but... it is a bit of a hacky and messy device. :-P

[davidofchatham]

Oh, great — thank you! I think I can make that work!

[davidofchatham]

I had hoped to use the GT-10 as a preamp and USB interface for PiPedal, and even use some of its effects before PiPedal. But running pipedal_latency_test never shows less than about 11.5ms latency for the successful tests — with everything turned off. Enabling effects blocks makes it a couple of milliseconds worse. Yikes!

Once it's possible to use separate interfaces for input and output, I may try again, probably with the S/PDIF output, and see if there's any significant improvement.

[rerdavies]

That is unfortunate. fwiw, one of the things I did not like about the GT-10 was that it FELT like it had high latency, even when not using USB inserts. Not enough to say for sure, but it always felt like "hard work" to play through a GT-10. Could just be that the GT+10's ordinary latency PLUS the additional latency of a a USB insert pushes things over the edge. Maybe.

Anyway. Sad that you can't get decent round-trip latency out of it. But probably a good thing to firmly establish, ahead of time, that it's not going to live up to expectations.

[davidofchatham]

Interesting — I think I'll try looping the GT-10 into the other interface that I have working (E-MU 0404 USB) and see how much latency is added by running through the GT-10 via its analog inputs and outputs.

[davidofchatham]

How strange! Looping through the analog I/O of the GT-10 only adds about 3ms latency, at most, with patches I use (effects enabled).

It seems something about the USB interface is very slow, relatively.