ALSA JACK Bridge ??

[avlmac]

I've implemented the ALSA Jack bridge as specified in the currently off line ALSA/JACK Bridge web page.

I've replaced the alsa in/out with the zita versions.

Both are working for example in a connection like:

Clementine > alsa > jack > AudioFire (output)

I have also recorded from a jack enabled source > zita_j2A > to an alsa app like Audacity.

But, I don't think I have a good understanding of the two areas:

1) the actual signal flow of the loopback devices (this might just be because I have not seen a diagram or tried to diagram it myself)

2) the signal flow coming from a jack source to alsa. For example, Audacity can see all the alsa "device" on the system (the mobo sound device, a usb sound device, and the alsa/jack devices. But I've not been successful in my attempts to send output from a jack sink to the mobo or usb device.

Anybody seen any diagrams? Or have a web site I've not found yet that has more explanations...Or lecture me in this thread.

Thanks, Mac

[varpa]

I probably cannot answer your questions but I'll throw out a few random comments:
o Bravo for trying the new zita-aj, glad it works, have not tried it myself.
o You example with Clementine seems unnecessary because Clementine will automatically connect to Jack anyway, if Jack it running.
o My dim understanding of the loopback device is it just loops an input to an output and vice versa creating an Alsa "device" for Jack to connect to using zita-aj or alsa_in/out.   Ok, I doubt this adds anything to your understanding.
o You say "I've not been successful in my attempts to send output from a jack sink to the mobo or usb device"  Isn't a "sink" a place ewhere to send data, in which case you could never send data from a "sink" to another device.  But maybe I misunderstand you.

[avlmac]

I probably cannot answer your questions but I'll throw out a few random comments:

o Bravo for trying the new zita-aj, glad it works, have not tried it myself.

zita-aj combined with zita crossover is pretty cool, I currently have a bi-amp system, hopefully soon, tri-amp with sub.

o You example with Clementine seems unnecessary because Clementine will automatically connect to Jack anyway, if Jack it running.

Yes, but good for prototyping system.

o My dim understanding of the loopback device is it just loops an input to an output and vice versa creating an Alsa "device" for Jack to connect to using zita-aj or alsa_in/out.   Ok, I doubt this adds anything to your understanding.

The whole "loops it back" is, I think my mental stumbling block...I keep thinking feedback.

o You say "I've not been successful in my attempts to send output from a jack sink to the mobo or usb device"  Isn't a "sink" a place ewhere to send data, in which case you could never send data from a "sink" to another device.  But maybe I misunderstand you.

Um...well, if I have a signal source shown in jack, say one of the inputs on the AF12. That's a source right (shown on the left hand side of the jack connection window)? So now it gets connected to zita-j2a on the right hand side. z-j2a now sending the signal to the alsa-loopback device. My question is how does that get routed to say the mobo or usb device? Alsa knows how to make noise on those devices, so I'm thinking something in .asoundrc should be able to make the route.

Is my visualization of the signal path correct?

[trulan]

The exact nature of the loopback device is confusing to say the least.  I've always used it with just one soundcard - either with Jack running on a firewire device or on my onboard soundcard, and all alsa audio getting routed to / through loopback.

When you take an input from your AF12 and connect it through jack to the loopback device, that makes it available to alsa applications as an audio source - ie, you could use a mic into your firewire device to talk on Skype, for instance (I've done this).  To loop that audio back to the loopback, then, would take another piece of software (something for alsa monitoring), but that would only succeed in getting the audio back into the Jack system and no closer to your MoBO soundcard.

To do what you want to do, (if it's even possible, I'm not sure), I believe you'd need another instance of zita-aj to pipe audio from jack to your alsa soundcard, seperate from the one that pipes audio from jack to the loopback device.  I'm not at all sure of this though.  But I believe that since you want to take Jack audio and route it to a real Alsa soundcard, you would use zita-j2a in a similar way to how you use it to get audio to the loopback device, only pointing it to the real soundcard instead.  The .asoundrc just tells alsa-aware applications to use the loopback device as their default soundcard, enabling these applications to actually find your jack audio ins and outs.

This explanation comes with no warranty expressed or implied.  Use at your own risk.