fix(j314): correct mic output routing and volume (#1)

[tristonarmstrong]

• fix(j314): use MONO channel position for mic playback output

AUX0 causes PulseAudio to route mono audio only to the front-left channel. MONO duplicates the signal to both speakers.

• fix(j314): set mic default output volume to 70%

The original commit (de0b801) set state.default-volume to 0.343 while the commit message stated 70%. The value 0.343 is 34.3%, not 70%. Corrected to 0.70 (70%).

[mkurz]

de0b801 also changed j316 and j415 - shouldn't those one also be fixed?

[tristonarmstrong]

de0b801 also changed j316 and j415 - shouldn't those one also be fixed?

I cant physically test those, despite it PROBABLY being a safe fix..
I can either go ahead with updating those as well with a maintainers go ahead, i guess
or someone else can come along and do it

For all i know audio position aux0 means something different on the 16inch and the person who made that commit could have had your same thought and was like, "shiiiiii they all need it ig".. lol

i can only confirm the one working is the one i changed.

[tristonarmstrong]

oop gotta sign this commits - will do that soon

[mkurz]

This is what gpt-5.6-sol says to this PR:

1. Incorrect volume conversion

The PR changes:

- "state.default-volume": 0.343,
+ "state.default-volume": 0.70,

PipeWire stores channel volume as a linear gain, while PulseAudio-compatible UIs use a cubic scale. WirePlumber’s documentation demonstrates this explicitly: 40% UI volume is stored as 0.4³. Therefore:

70%³ = 0.7³ = 0.343

So 0.343 already means 70% UI volume. 0.70 would appear as approximately 89% and roughly doubles the gain—about +6.2 dB. That risks reintroducing the clipping which the original de0b801 commit explicitly intended to prevent. See the WirePlumber cubic-volume example and PipeWire’s linear channel-volume definition.

Additionally, state.default-volume is only used when WirePlumber has no previously saved volume. Consequently, it may not change anything on an existing installation already displaying 100%. WirePlumber documents that behavior here.

Required correction: keep 0.343.

2. AUX0 → MONO is conceptually correct

The other change is:

- "audio.position": ["AUX0"]
+ "audio.position": ["MONO"]

This is the exposed, processed, single-channel Audio/Source. PipeWire’s own downmix-source example uses AUX channels on the capture side and MONO on the exposed source side—exactly this arrangement. MONO is therefore the appropriate output channel designation.

This does not conflict with 43f4ff8:

Raw microphones [AUX0, AUX1, AUX2]
        → beamforming/filter
        → processed source [MONO]

The PR description saying it “duplicates the signal to both speakers” is imprecise. It marks the source semantically as mono, allowing normal downstream channel mixing; the configuration itself does not explicitly copy samples to speakers.

[tristonarmstrong]

hmmmm.. Ok so ill keep state.default-volume set the way it was despite that fixing my low mic issue maybe theres a better approach on my end

and yeah semantics aside, mono was DEFINITELY needed lol

[tristonarmstrong]

ive made the changes and signed my commit