[LAU] Confusing qjackctl playback devices, no jackd output

[Len Ovens]

On Tue, 8 Jul 2014, Paul Davis wrote:
> 
> On Tue, Jul 8, 2014 at 8:03 AM, Roberto Suárez Soto <talkingxouba at gmail.com>
> wrote:
> ...
>
>           After messing around for a while, I found that I could make
>       hydrogen sound again changing the connections in qjackctl
>       "Connections" window: instead of connecting the two outputs of
>       hydrogen to "playback_1" and "playback_2" (which is the default as
>       soon as hydrogen is started), I connected them to "playback_7" and
>       "playback_8". I have a built-in HDA-intel sound card, and I believe
>       that these outputs are "side-left" and "side-right". But I had never
>       had to do this, playback_1 and playback_2 always worked. I'm using
>       headphones, in case that's important.
> 
> 
> I have two systems which work the same way. Where the first two channels shows up
> depends on precisely which device (hw:N,n) is opened. With one version, they show
> up on 7&8 (the default hw:0,0) and with the other on 1&2 (can't recall the
> precise device incarnation).

HDA audio has a unique "feature" called "jack sensing" (jack in this case 
is not jackd) where it changes how the audio interface is laid out by what 
it senses you have plugged in. This allows the MB to have fewer HW jacks 
while still having lots of i/o. there is an application called 
HDAJackRetask that _may_ help. Be aware that plugging and unplugging 
things will change how things are set up. Dirty contacts may effect things 
too.

> Its sort of a feature of ALSA, and sort of a really bad piece of
> non-user-oriented design thinking.

Unfortunately for ALSA, HDA is not a standard audio interface layout so 
much as a bus standard (from what I can tell). If you look at the HDA 
driver, there is a long list arguments that tell the driver which HDA you 
have.

The ideal solution is a better audio interface, but often that would cost 
as much as the computer, though there are a number of two channel USB 
interfaces for less than $100 too.

--
Len Ovens
www.ovenwerks.net