Yeah, the individual messages thing is great, but also kinda weird. The typical use case for a note-on message is to turn a note on, which is why the keywords `freq`, `gate`, and `gain` are great as generic catch-alls for a poly (or mono) instrument.
I can see how it's more generally cool and useful for `0xBn` control signals. What you propose, Stéphane, could work - "[midi:on CHAN]"... and/or having the ability to specify `-midi_channel X` where X is 1-16, on the command line wrapper script. Either way would be better than having to manually hack the `.cpp` file! Aaron Krister Johnson Music, etc.: https://soundcloud.com/aaron-krister-johnson https://soundcloud.com/filtercreed https://www.youtube.com/channel/UC_utjGYbSizWE0dNyr0Vdmg https://aaronkristerjohnson.bandcamp.com/ http://www.untwelve.org Code: https://github.com/akjmicro <http://www.untwelve.org> On Tue, Dec 9, 2025 at 3:11 PM Stéphane Letz <[email protected]> wrote: > See : https://faustdoc.grame.fr/manual/midi/#configuring-midi-in-faust > > We already have MIDI channel for individual messages , > > We could possibly extend the global: declare options "[midi:on] »; with > an extended version: declare options "[midi:on CHAN] »; that would > specific a given CHAN for all MIDI aware controllers ? > > Stéphane > > > Le 9 déc. 2025 à 22:30, Aaron Krister Johnson <[email protected]> a > écrit : > > > > Hi, > > > > In case anyone else was interested in this issue, I wanted to report my > process to successfully get a Faust executable for e.g. a synth to only > listen to one particular MIDI channel (by default, for ON, OFF, CTRL, BEND > messages will respond to ALL MIDI channels). > > > > In short, if you look at what the shell scripts that compile a `.dsp` > file do, they first call `faust` to get a `.cpp` file that wraps an > architecture file. If you recreate this process by seeing what the actual > command that run are with bash debugging on: > > > > bash -x /usr/bin/faust2jackconsole -osc -midi -nvoices 1 > your_synth.dsp > > > > ...you'll see the `faust` command that spits out a `.cpp` file. Run this > separately, then edit lines that look something like: > > > > if (type == MIDI_NOTE_ON) { > > ... > > } > > > > and change them to: > > > > if (type == MIDI_NOTE_ON & channel == 2) { // if you want to only > listen on channel 3 > > ... > > } > > > > Do this for the stanzas for `MIDI_NOTE_OFF`, `MIDI_PITCH_BEND`, etc. and > any message type you want to filter by channel. > > > > Once you've finished editing the `.cpp` file, continue running the `c++` > command you saw the faust wrapper script (e.g. `faust2jackconsole`) spit > out. > > > > When you test it, you'll see that your instrument will properly only > respond to the midi channel you edited it to respond to. Bear in mind, midi > channel 1 is `0` in code, and 2 is `1`, etc. etc. i.e. for MIDI_NOTE_ON: > > > > 0x90 // channel 1 > > 0x91 // channel 2 > > 0x92 // channel 3 > > etc. etc. > > > > Hope this helps someone else wanting to do the same. > > > > Devs: should be a simple matter to make this dynamic from `faust` itself > so that the front-end can make this easy with an extra optional parameter, > like so....?: > > > > faust2jackconsole -osc -midi -nvoices -midi_channel 4 -effect auto > my_synth.dsp > > > > Where `-midi_channel ...` would be the new option that would effectively > alter those intermediate `.cpp` lines I refer to. > > > > Aaron Krister Johnson > > Music, etc.: > > https://soundcloud.com/aaron-krister-johnson > > https://soundcloud.com/filtercreed > > https://www.youtube.com/channel/UC_utjGYbSizWE0dNyr0Vdmg > > https://aaronkristerjohnson.bandcamp.com/ > > http://www.untwelve.org > > Code: > > https://github.com/akjmicro > > > > > > On Mon, Sep 29, 2025 at 9:27 AM Stéphane Letz <[email protected]> wrote: > > Not much time to work on that right now yes. > > > > Stéphane > > > > > Le 29 sept. 2025 à 18:26, Aaron Krister Johnson <[email protected]> > a écrit : > > > > > > Stephane et al, > > > > > > Gentle nudge here: any more thoughts on this MIDI channel issue, or is > the best approach for now to work (or hack) around it? > > > > > > Aaron Krister Johnson > > > Music, etc.: > > > https://soundcloud.com/aaron-krister-johnson > > > https://soundcloud.com/filtercreed > > > https://www.youtube.com/channel/UC_utjGYbSizWE0dNyr0Vdmg > > > https://aaronkristerjohnson.bandcamp.com/ > > > http://www.untwelve.org > > > Code: > > > https://github.com/akjmicro > > > > > > > > > On Sun, Sep 21, 2025 at 9:29 AM Aaron Krister Johnson < > [email protected]> wrote: > > > I guess this is a hack, but for keyOn and keyOff coming from the > polyphony code (which I traced from looking for `freq` references) I'm > thinking changing these in `poly-dsp.h` to further filter by channel at > compile time would be key? > > > > > > // MIDI API > > > MapUI* keyOn(int channel, int pitch, int velocity) > > > { > > > if (checkPolyphony()) { > > > int voice = getFreeVoice(); > > > fVoiceTable[voice]->keyOn(pitch, velocity, > fVoiceTable[voice]->fCurNote == kLegatoVoice); > > > return fVoiceTable[voice]; > > > } else { > > > return 0; > > > } > > > } > > > > > > void keyOff(int channel, int pitch, int velocity = 127) > > > { > > > if (checkPolyphony()) { > > > int voice = getPlayingVoice(pitch); > > > if (voice != kNoVoice) { > > > fVoiceTable[voice]->keyOff(); > > > } else { > > > fprintf(stderr, "Playing pitch = %d not found\n", > pitch); > > > } > > > } > > > } > > > > > > Change to: > > > > > > // MIDI API > > > MapUI* keyOn(int channel, int pitch, int velocity) > > > { > > > if (checkPolyphony() & (channel == 1)) { // to respond > only to MIDI channel 2, actual number is MIDI channel - 1 > > > int voice = getFreeVoice(); > > > fVoiceTable[voice]->keyOn(pitch, velocity, > fVoiceTable[voice]->fCurNote == kLegatoVoice); > > > return fVoiceTable[voice]; > > > } else { > > > return 0; > > > } > > > } > > > > > > void keyOff(int channel, int pitch, int velocity = 127) > > > { > > > if (checkPolyphony() & (channel == 1)) { // to respond > only to MIDI channel 2, actual number is MIDI channel - 1 > > > int voice = getPlayingVoice(pitch); > > > if (voice != kNoVoice) { > > > fVoiceTable[voice]->keyOff(); > > > } else { > > > fprintf(stderr, "Playing pitch = %d not found\n", > pitch); > > > } > > > } > > > } > > > > > > But yes, would be better to allow the polyphony/voice-table > architecture to be more standards compliant about channels, I'm thinking. > I'll test this, for now it will do if it works. > > > > > > Aaron Krister Johnson > > > Music, etc.: > > > https://soundcloud.com/aaron-krister-johnson > > > https://soundcloud.com/filtercreed > > > https://www.youtube.com/channel/UC_utjGYbSizWE0dNyr0Vdmg > > > https://aaronkristerjohnson.bandcamp.com/ > > > http://www.untwelve.org > > > Code: > > > https://github.com/akjmicro > > > > > > > > > On Sun, Sep 21, 2025 at 8:26 AM Aaron Krister Johnson < > [email protected]> wrote: > > > Is this MIDI channel filtering option being considered? If not, would > the dev team welcome a patch if I tried my hand at it? > > > > > > ~AKJ > > > > > > Aaron Krister Johnson > > > Music, etc.: > > > https://soundcloud.com/aaron-krister-johnson > > > https://soundcloud.com/filtercreed > > > https://www.youtube.com/channel/UC_utjGYbSizWE0dNyr0Vdmg > > > https://aaronkristerjohnson.bandcamp.com/ > > > http://www.untwelve.org > > > Code: > > > https://github.com/akjmicro > > > > > > On Fri, Sep 12, 2025, 13:31 Aaron Krister Johnson <[email protected]> > wrote: > > > Ah, so it seems others have bumped into this limitation. > > > > > > Please, Faust devs, implement this! :D > > > > > > Aaron Krister Johnson > > > Music, etc.: > > > https://soundcloud.com/aaron-krister-johnson > > > https://soundcloud.com/filtercreed > > > https://www.youtube.com/channel/UC_utjGYbSizWE0dNyr0Vdmg > > > https://aaronkristerjohnson.bandcamp.com/ > > > http://www.untwelve.org > > > Code: > > > https://github.com/akjmicro > > > > > > > > > On Thu, Sep 11, 2025 at 2:17 AM <[email protected]> wrote: > > > Additional reading here: > https://github.com/grame-cncm/faust/discussions/696 > > > > > > All of this must be carefully considered... > > > > > > Stéphane > > > > > > > Le 10 sept. 2025 à 19:26, Aaron Krister Johnson <[email protected]> > a écrit : > > > > > > > > P.S. -- and if this is implemented, covering key/vel/velocity, too :D > > > > > > > > Aaron Krister Johnson > > > > Music, etc.: > > > > https://soundcloud.com/aaron-krister-johnson > > > > https://soundcloud.com/filtercreed > > > > https://www.youtube.com/channel/UC_utjGYbSizWE0dNyr0Vdmg > > > > https://aaronkristerjohnson.bandcamp.com/ > > > > http://www.untwelve.org > > > > Code: > > > > https://github.com/akjmicro > > > > > > > > > > > > On Wed, Sep 10, 2025 at 10:23 AM Aaron Krister Johnson < > [email protected]> wrote: > > > > Thanks, Stephane, yes, it would be most useful to have a Faust synth > only respond on a declared channel, and `0` (or no specification) being > "listen on all channels". > > > > > > > > Would this be in the "options" header, then? > > > > > > > > Aaron Krister Johnson > > > > Music, etc.: > > > > https://soundcloud.com/aaron-krister-johnson > > > > https://soundcloud.com/filtercreed > > > > https://www.youtube.com/channel/UC_utjGYbSizWE0dNyr0Vdmg > > > > https://aaronkristerjohnson.bandcamp.com/ > > > > http://www.untwelve.org > > > > Code: > > > > https://github.com/akjmicro > > > > > > > > > > > > On Wed, Sep 10, 2025 at 9:00 AM Stéphane Letz <[email protected]> wrote: > > > > Hi Aaron, > > > > > > > > MIDI metadata for standard MIDI control can use MIDI channel: > https://faustdoc.grame.fr/manual/midi/#configuring-midi-in-faust > > > > > > > > But it is currently not possible to set a given channel for > polyphony, you can see that the channel info is not used in the polyphonic > code for now: > > > > > > > > > https://github.com/grame-cncm/faust/blob/f5c23da4fe6e09fa55667ae588f4b6ef9c226cae/architecture/faust/dsp/poly-dsp.h#L900 > > > > > > > > Should we extend/revisit the syntax of freq/gate/gain convention for > something like [freq: chan], [gate: chan], [gain: chan], with the > convention chan = 0 would mean « receive on all channels», like for other > MIDI messages ? > > > > > > > > Stéphane > > > > > > > > > Le 10 sept. 2025 à 17:35, Aaron Krister Johnson < > [email protected]> a écrit : > > > > > > > > > > I notice in the manual, certain MIDI slider metadata operations > can be filtered by a certain MIDI channel, like `keyon` uses the velocity > of a given key on a given channel. > > > > > > > > > > But IMO, these kinds of operations seem geared towards a > non-standard way of using a MIDI signal. Most useful mono- or poly- synths > would want to use the general > > > > > keywords with special meaning: `freq/key`, `gain/vel`, and `gate` > to drive the usually needed MIDI parameters in, for instance, a synthesizer > signal chain. > > > > > > > > > > The problem I am having is: I'd like to pair a custom Faust synth > with an outboard analog monosynth. Ideally, I could assign Faust to listen > only on a certain MIDI channel. > > > > > As it is, it seems like I have to do the opposite: Faust will > respond to _all_ channels (not ideal) and I make the hardware synth respond > to MIDI channel 2. They are isolated only > > > > > by the fact that they are listening on different MIDI ports > (otherwise, the Faust synth would be "hearing" both channels and trying to > respond to both). What I have works for now, > > > > > but let's say I want 2 Faust synths -- they'd both be responding > to all channels that particular virtual port is listening on. > > > > > > > > > > So, in short: is there an easy way to make a running Faust synth > instance listen only to a particular MIDI channel when it's designed to use > the keywords `freq`, `gain`, and `gate`, > > > > > per the docs? How easy would it be to hack Faust or add a feature > for users for this if not? > > > > > > > > > > Aaron Krister Johnson > > > > > Music, etc.: > > > > > https://soundcloud.com/aaron-krister-johnson > > > > > https://soundcloud.com/filtercreed > > > > > https://www.youtube.com/channel/UC_utjGYbSizWE0dNyr0Vdmg > > > > > https://aaronkristerjohnson.bandcamp.com/ > > > > > http://www.untwelve.org > > > > > Code: > > > > > https://github.com/akjmicro > > > > > _______________________________________________ > > > > > Faudiostream-users mailing list > > > > > [email protected] > > > > > https://lists.sourceforge.net/lists/listinfo/faudiostream-users > > > > > > > > > > >
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