[pulseaudio-discuss] [PATCH v0 01/11] card: Support adding profiles dynamically

David Henningsson david.henningsson at canonical.com
Tue Oct 23 01:14:21 PDT 2012

On 10/23/2012 08:01 AM, Mikel Astiz wrote:
> Hi David,
> On Mon, Oct 22, 2012 at 6:10 PM, David Henningsson
> <david.henningsson at canonical.com> wrote:
>> On 10/22/2012 10:46 AM, Mikel Astiz wrote:
>>> From: Mikel Astiz <mikel.astiz at bmw-carit.de>
>>> Some cards might need to add profiles during their lifetime, that is,
>>> after the card has been created.
>> How are volume control UIs, other modules, etc made aware that the profiles
>> or ports of a card has changed?
> I believe the D-Bus API as well as the subscription events would have
> to be extended for this purpose, but I haven't addressed either of
> these here. Any thoughts?

Just that being able to change a card in ways that was not possible 
before, is something that require careful thought. Removal even more so; 
what if a volume control UI starts (that was built before we made this 
change), and suddenly a profile is removed, and then the user tries to 
select this profile?

I'm also not sure if there are other parts of the PulseAudio core that 
needs to know if things like these change, do you know?

I'm not opposed to the change, maybe it is inevitable - e g, the 
capabilities of HDMI sinks can also change during PulseAudio's life 
time, so that's another example of dynamic profiles. What I'm trying to 
say here is that:

1) This is a quite fundamental change of behaviour, have we thought this 
through thoroughly, with all the consequences not only for us but for 
our client software as well?


2) I don't want to release with this being half-done; e g, if we add 
profiles without a subscription mechanism and then release, we might end 
up with volume control UIs polling us all the time to work around our 
own shortcomings.

David Henningsson, Canonical Ltd.

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