Jack midi connections window

[flagos]

Hi. I have some doubts concerning the Jack midi connections.

In my system I have an MAudio Audiophile 2496 card which has one midi input and one midi out. And I have a keyboard controller connected to that midi in. That's all I have.

So, why I have three midi_capture items in the left, and three midi_playback items in the right? Anybody can explain this, or perhaps point me to some documentation to learn about it?

Thanks!

[RyanH]

Someone will probably answer this better than I will, but I can give you a partial answer.

The first MIDI capture and playback entries are part of the Linux system. If you unplug everything, you'll see they're still there.

For the other two, one is of course your gear. Maybe your card for some reason provides two entries (even though it just has one in and one out), or else... do you have any DAW or other software open? If I have, for example, QTractor open, I will see that first midi_capture_1 that's always there, plus one or more additional entries for QTractor, which let me connect my gear to the track I'm recording or connect an already recorded track to, say, a software synth (so I can play MIDI clips that I've recorded out to an external synth).

Hope that helps.

[RyanH]

I'd like to add...

I find this MIDI connections window difficult, because nothing has a name. I usually use the ALSA window, which is also for MIDI (I know, confusing - two tabs for MIDI, one called "MIDI" and one not). Unlike the MIDI tab, this ALSA tab shows the names of the equipment and also the software connected to it. For example, right now I have an M-Audio Oxygen keyboard connected, so the ALSA tab shows me the first default Midi Through entry that's always there, plus one for Oxygen 49. If I open Yoshimi synth, it also pops up as "Yoshimi" in the window. However...

To use the ALSA tab for software (like synths, DAWs), you have to make sure the software is set in its settings to use ALSA rather than Jack. When I do this, most of the software I use will then pop up in the ALSA tab, but not all. For software that doesn't show in the ALSA tab, you can still connect your synth or whatever to Midi Through in the ALSA tab and then it will be available as one of those unnamed entries in the MIDI tab that your question was about.

Hope this all makes sense.

Cheers.

[alex stone]

Hi. I have some doubts concerning the Jack midi connections.

In my system I have an MAudio Audiophile 2496 card which has one midi input and one midi out. And I have a keyboard controller connected to that midi in. That's all I have.

So, why I have three midi_capture items in the left, and three midi_playback items in the right? Anybody can explain this, or perhaps point me to some documentation to learn about it?

Thanks!

The third port, in and out, is likely midi through.

The three tabs are audio (obviously), jack midi, and alsa midi. If you look at the third tab, it will show three ports in and out, yes? These ports are mirrored in the jack midi tab.

If you have an app that has only jack midi ports, then they will only show in the middle tab.

Remember, the module in the kernel that enables your audio card is part of the ALSA system. It's part of the "hardware" space.

Jack sits on top of ALSA, in USER space, and gives you the opportunity to open several apps, all of which will be able to access audio and midi, at the same time, where ALSA will only let you use one app at a time. (The other bonus with using JACK is its sample accurate timing.)

The reason you have three tabs originates from a very clever app called a2jmidid, which is now part of qjackctl (if i'm correct).

As the start of the name "A 2 J" implies, it creates a jack port for each ALSA port, and is shown in the center tab. This means if you have a mixture of apps that use ALSA midi or JACK midi, they can all be connected to each other using the middle tab as both native and "mirrored" JACK ports.

I hope i've explained this correctly, and that you understand my clumsy attempt at clarification.


Alex.

[flagos]

Thanks to all! It helped a lot!!

[RyanH]

Hi. I have some doubts concerning the Jack midi connections.

In my system I have an MAudio Audiophile 2496 card which has one midi input and one midi out. And I have a keyboard controller connected to that midi in. That's all I have.

So, why I have three midi_capture items in the left, and three midi_playback items in the right? Anybody can explain this, or perhaps point me to some documentation to learn about it?

Thanks!

The third port, in and out, is likely midi through.

The three tabs are audio (obviously), jack midi, and alsa midi. If you look at the third tab, it will show three ports in and out, yes? These ports are mirrored in the jack midi tab.

If you have an app that has only jack midi ports, then they will only show in the middle tab.

Remember, the module in the kernel that enables your audio card is part of the ALSA system. It's part of the "hardware" space.

Jack sits on top of ALSA, in USER space, and gives you the opportunity to open several apps, all of which will be able to access audio and midi, at the same time, where ALSA will only let you use one app at a time. (The other bonus with using JACK is its sample accurate timing.)

The reason you have three tabs originates from a very clever app called a2jmidid, which is now part of qjackctl (if i'm correct).

As the start of the name "A 2 J" implies, it creates a jack port for each ALSA port, and is shown in the center tab. This means if you have a mixture of apps that use ALSA midi or JACK midi, they can all be connected to each other using the middle tab as both native and "mirrored" JACK ports.

I hope i've explained this correctly, and that you understand my clumsy attempt at clarification.


Alex.

I learned something from your answer, but I might be misunderstanding one thing, about ALSA only letting you use one app at a time. If I open, say, QSynth and Yoshimi, they both show up and are usable in the ALSA tab. Did you mean that ALSA only allows one at a time when used without the Jack server started?

[alex stone]

Hi. I have some doubts concerning the Jack midi connections.

In my system I have an MAudio Audiophile 2496 card which has one midi input and one midi out. And I have a keyboard controller connected to that midi in. That's all I have.

So, why I have three midi_capture items in the left, and three midi_playback items in the right? Anybody can explain this, or perhaps point me to some documentation to learn about it?

Thanks!

The third port, in and out, is likely midi through.

The three tabs are audio (obviously), jack midi, and alsa midi. If you look at the third tab, it will show three ports in and out, yes? These ports are mirrored in the jack midi tab.

If you have an app that has only jack midi ports, then they will only show in the middle tab.

Remember, the module in the kernel that enables your audio card is part of the ALSA system. It's part of the "hardware" space.

Jack sits on top of ALSA, in USER space, and gives you the opportunity to open several apps, all of which will be able to access audio and midi, at the same time, where ALSA will only let you use one app at a time. (The other bonus with using JACK is its sample accurate timing.)

The reason you have three tabs originates from a very clever app called a2jmidid, which is now part of qjackctl (if i'm correct).

As the start of the name "A 2 J" implies, it creates a jack port for each ALSA port, and is shown in the center tab. This means if you have a mixture of apps that use ALSA midi or JACK midi, they can all be connected to each other using the middle tab as both native and "mirrored" JACK ports.

I hope i've explained this correctly, and that you understand my clumsy attempt at clarification.


Alex.

I learned something from your answer, but I might be misunderstanding one thing, about ALSA only letting you use one app at a time. If I open, say, QSynth and Yoshimi, they both show up and are usable in the ALSA tab. Did you mean that ALSA only allows one at a time when used without the Jack server started?

I think that's correct, yes. (I haven't used ALSA directly for over a decade, so something may have changed.) The only way to use ALSA with multiple apps at once was to hack .asoundrc, or use an app called dmix. You need to output to the dmix ALSA device instead of the default device; that allows multiple streams to be mixed and output to the sound card. Dmix only works for outputs, so you'd need to use another app called dsnoop to manage the inputs. (And there are conditions for using dmix as well. The first app you open must be set to dmix, or it will block all the other apps)


Jack made all this far far easier to manage. And I think pulse audio does the same. Mixes multiple streams together, before outputting to ALSA/hardware.

Alex.