[pulseaudio-discuss] Headset-detection

Colin Guthrie gmane at colin.guthr.ie
Thu Jul 21 13:12:54 PDT 2011

'Twas brillig, and Himanshu Chug at 21/07/11 08:24 did gyre and gimble:
> Thanks Colin and Spidey for making this clarification.
> So regarding JACK detection and routing:
> 1. module-udev-detect currently can detect JACK physical hot-plugging
> but it can't decode the information about what type of JACK device (
> input or output ) is connected to the sound-card, and for that one need
> to write an JACK detection module to handle that.
> is my understanding correct ?

Not quite. Udev detect does absolutely nothing with JACKs. It detects
totally new devices in a hotplug way. These devices are e.g. USB
speakers or headsets.

The actual HP Jack detection stuff is not present at all in PA as the
underlying layers in ALSA are in flux. These need to settle before we
can write anything to deal with them.

There are active discussions on this topic just now on the alsa-devel
mailing list.

> 2 Currently our Kernel/ALSA team support for providing seperate kcontrol
> (amixer scripts) for enabling/disabling loudspeaker and headset to PA,
> so it might be an good idea to handle Jack detection and routing in one
> of the existing module or write up an new jack detection module for
> this, as Colin suggested, provided that we are able to recognize Jack
> device type  (input/mic or output/headset or both)  from point 1, ( i
> will take further help from kernel team here about detecting jack device
> type, but any suggestions are welcome :-) )

Kinda. PA should be able to display to you the different "ports" for
each sink. These ports represent the Speakers or the Headphones
kcontrols that are on your device and you can change ports at runtime
(just run pavucontrol and if your sinks actually have ports, there will
be a drop downo n the "Output Devices" pane). At present you have to
change ports manually but the plan is to hook this up to jack detection,
such that the port is simply flipped accordingly.

Multifunction jacks (i.e. those that can be input or output, analog or
digital) are even more interesting :)

I very strongly suggest you discuss this with David Henningsson. He's on
this list but is away on vacation for (I think) another week. He's is
actively working on JACK support for ALSA and PA layers so it will
likely be the most productive for you if you wait and speak with him.
He's employed by Canonical and is diwic on IRC.



Colin Guthrie

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