[pulseaudio-discuss] Auto-switching to and from HDMI ports (audio)

[Jarkko Suontausta]

Hi David,

On Friday 16 March 2012 03:48:14 David Henningsson wrote:
> Hi,
> 
> I'm not exactly sure who I should send this to, so maybe I'm a little
> too inclusive here. Anyway.
> 
> The use case here is that your laptop speakers are active (or at least
> currently selected) and you plug an HDMI [1] cable in and activate the
> screen.
> Should we, or should we not, automatically change the audio output to be
> to the HDMI output?
> And likewise, when the cable is unplugged / the HDMI screen deactivated,
> should we, or should we not, change the audio output back to the speakers?
What I'm most concerned about personally is that the end user should be able 
to specify the desired behavior. In my opinion, Pulseaudio should only provide 
the routing mechanisms and configurability, not the policies themselves. Of 
course, it can provide reasonable defaults, but it's impossible to mandate 
policies that would work everywhere and for everyone. I think the worst case 
would be to code some "cleverness" into Pulseaudio which cannot be easily 
overridden.

So, I guess my main question is that how would this functionality be 
configurable? I wouldn't think tweaking default.pa would be a good option 
here.

>   * switching from HDMI but never to HDMI: assuming we're not certain
> that the user wants to use HDMI audio just because (s)he plugged it in,
> we could quite safely assume that (s)he does not want to use an
> unplugged HDMI cable. However, if we want to do this consistently, we
> still suffer from having to set the default sink.
In my view, this is the only decision that can be made on behalf of the user. 
But is it necessary to change the default sink the user has set? If the HDMI 
output becomes available, it could be selected automatically if the user has 
chosen that way. If the priority is lower than the internal speakers, then it 
wouldn't be automatically selected.

(FWIW, I think the default sink concept is too limiting, and should only be 
considered as a fallback. Pulseaudio has quite novel routing capabilities 
based on stream properties, available profiles and ports etc., so why not use 
those?)

All the best,
--
Jarkko