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

David Henningsson david.henningsson at canonical.com
Fri Mar 16 01:05:09 PDT 2012

On 03/16/2012 03:06 AM, Tanu Kaskinen wrote:
> On Fri, 2012-03-16 at 02:48 +0100, David Henningsson wrote:
>> As I see it we have a couple of options.
>>    * no auto switching between HDMI and analog outputs at all. This is
>> probably the simplest option. But maybe this is not the most user
>> friendly option?
>>    * full switching. This requires not only profile switching on plug and
>> unplug, but also switching between cards, i e moving streams between
>> cards, and updating the default sink. More work, but definitely doable.
>> I get the feeling that we want to avoid updating the default sink when
>> it's not a direct user action though?
> I guess you are more familiar with the use cases, but wouldn't it be
> common to attach a monitor without wanting to use the monitor's audio
> output? If that's the case, I think auto-switching isn't really a good
> idea.

I don't know how common it is to want to use, vs does not want to use, 
the audio output of an HDMI monitor. That's part of why I'm asking :-)

Also, I don't know if it's possible/common that the HDMI monitor lies to 
us about its audio capabilities, so that it would say that it has audio 
capabilities when it does not. I did however test connecting my DVI 
monitor over HDMI and that one correctly did not show up as having audio 

> If you are going to do the auto-switching anyway, I think the default
> sink should be changed too. Behaving differently with existing and
> not-yet-existing streams doesn't make sense to me.
>>    * switching only if the HDMI outputs are on the same card as the
>> analog output. This is also simple to achieve, but might be confusing
>> for users and support engineers?
>>    * 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.
>> What do you think?
> For what it's worth (I'm not a usability expert), to me the last option
> sounds the best policy, with default sink updating.

Cool, thanks for the input. What do others think?

David Henningsson, Canonical Ltd.

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