07.02.2015 10:22, Raymond Yau wrote:
>
>> 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
It is not the job of the application to react to this. PulseAudio can
downmix 5.1 to stereo just fine. Besides, such switching of the number
of channels already happens when the user moves the audio stream from
the movie player from 5.1 HDMI sink of his video card to the built-in
stereo audio. So - no reason to worry at all.
No comments about the questions in the remainder of your email, because
I am not sure I understand them correctly.
--
Alexander E. Patrakov
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