[LAU] Jack fallback to alsa when firefire device off?

[Robin Gareus]

On 02/17/2011 10:53 AM, Dan Capp wrote:
> This was my question in IRC – and thanks to those investigating on my
> behalf. I’m a total Linux newbie. Let me do my best to explain:
> 
> 
> 
> I’m on KXStudio, where all audio goes through Jack (as I understand it).
> When I switch my firewire device (Phonic Firefly) on, jack recognizes it
> straight away and runs all audio through it instead of my onboard PCM.
> That’s great! However, if I want to turn my firewire device off and have all
> sound go through the onboard PCM again (and subsequently my built-in
> computer speakers), this doesn’t work! When I turn the firewire off, jack
> simply stops completely and I have to ‘force restart’ a couple of times to
> get sound out of my speakers.
> 
> 
> It’s not the end of the world – I just wondered if it’s fixable as Windows
> was able to automatically switch between my firewire and onboard cards with
> no problem. 

/me does a double take: If you'd said "as in OSX" I'd believe you ;-)


Currently there only solution is to take manual action:

- tell JACK to use internal soundcard _before_ disconnecting the
Firewire device.

- tell JACK to use the Firewire _after_ connecting and turning it on.

The latter /could/ be automated, however there is no OutOfTheBox tool
that does that; it also requires JACK2 with d-bus support enabled. AFAIK
there is no GUI that can do this easily. If you want to know details and
are not afraid of the command-line: please call again.

Every studio is different: the connections to speakers may be on
different ports and it be too easy to blow sth up if JACK tried to be
smart when automatically switching interfaces.

While it would be nice to have for a home or mobile studio, features
like this are being frowned on in professional studio environment. I
don't think we'll see this automatic device-switch feature become
available in JACK soon.

> I’m a graphic designer by trade and if I’m just listening to
> music I don’t want to use my firewire device to do so. But if inspiration
> strikes spontaneously I just want to switch my firewire on, lay down some
> recordings, then turn it off and go back to using onboard audio… preferably. 

The workflow you describe sounds like it is rather separated anyway.
 internal-soundcard: listening to music
 firewire-interface: recording/mixing etc.

Why don't you use JACK _only_ for the firewire device? and configure
your music-player to use ALSA (or pulseaudio) on the built-in card?

2c,
robin

> Sorry if my terminology’s off – just say if I can explain myself better.
>
> - Dan Capp
>
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