Follow-up: If there were an option for MIDI channel, perhaps to preserve old behavior, when unspecified, the `freq, gain, gate`, etc...respond to ALL MIDI channels, and thus, when specified, it can be _only_ the channel specified.
In other words, "all" would be the default, equivalent to `-midi_channel all` on the commandline. Whereas `-midi_channel 1` would only respond to `midi_channel == 1`. Ditto `[midi:on CHAN]` in options -- not giving a CHAN might be equivalent to the current "all" behavior, but specifying one gives the "single channel filter" logic? 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 3:38 PM Aaron Krister Johnson <[email protected]> wrote: > 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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