[pulseaudio-discuss] Profile switching on headphone plugging (was: LFE filter)

[Raymond Yau]

>
>> Hrm, that is actually a good question. In theory, I would expect
>> module-switch-on-port-available to switch profiles between 2.0 and 2.1
>> as headphones are plugged in and out, but in practice,
>>
>>   - I'm not 100% sure if our "don't switch to HDMI" might prevent
>> switching from 2.1 to 2.0 when headphones are plugged in, and
>>
>>   - As the 2.0 profile is available on speakers, that will continue to
>> be selected when headphones are unplugged.
>>
>> So, while this is not directly related to whether there is an LFE filter
>> or not - we already have a 2.1, 5.1, etc, profiles - indeed the problem
>> might become worse with the LFE filter.
>
>
> Well, I have just tested how today's git version of pulseaudio (without
your patch) behaves when plugging headphones. Yes - the problem is
pre-existing.
>
> The PC under test has analog outputs on the back panel that,
theoretically, can be used as analog 5.1 outputs, and also has headphone
and microphone sockets at the front panel.
>
> So, the test is:
>
> 1. Make sure something (I tested with a cable extender) is plugged in the
line output on the back panel.
> 2. Select the "analog stereo duplex" profile in pavucontrol.
> 3. Look at the Playback devices tab. It should say: Port: Line Out
(plugged in).
> 4. Plug in headphones at the front. Note that the port changes to:
Headphones (plugged in). I.e. exactly as expected.
> 5. Unplug the headphones, watch how the port changes back to Line Out
(plugged in).
> 5. Now select the Analog Surround 5.1 + Stereo Input as a profile. Now
the port stays as Line Out (plugged in), but the volume control becomes
6-channel.
> 6. Plug headphones in. Result: the port stays as Line Out (plugged in),
with 6-channel volume control, and speaker-test -c6 does not reach
headphones.
>
> Sorry, I cannot retest this at home without additional jack-retasking
(which could make the result untrustworthy), because my home PC does not
have any audio sockets at the front panel.
>

I have doubt about changing 5.1 profile to stereo when headphone is plugged
since most user use 5.1 profile to watch movie, changing 5.1 profile to
stereo require stop playback of 5.1 and start stereo playback , how can the
application perform video audio sync for this kind of profile switching

Do pulseaudio switch back to 5.1 profile when headphone is pkugged ?

https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/1040873

For those Asus N series notebook with external Sonic Master subwoofer,
Seem using jack detection of spdif pin complex for the propretiary jack of
the subwoofer , you need driver create an adhoc jack detection control if
you want to switch from stereo to 2.1 profile when the subwoofer is plugged
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