Isolate the Scarlett microphone capture channel (V-487)

deploy/mavwaked.service

@@ -32,6 +32,7 @@
 # means out of this unit's own journal, never by guessing.
 #
 #   install: cp to ~/.config/systemd/user/ on workpc
+#            cp ../deploy/asoundrc to ~/.asoundrc on workpc
 #            systemctl --user enable --now mavwaked.service
 
 [Unit]
@@ -46,22 +47,30 @@ After=maven-voice-tunnel.service
 # it returns RMS 0.00004 with its capture switch on and its ALSA volume at the
 # full 496 of 496. That silence is in the hardware, so no flag reaches it.
 #
-# Named CARD=Gen and not card 4, because a USB card number moves when
-# something else is replugged and this daemon must not change ears quietly.
+# mavmic and not plughw:CARD=Gen,DEV=0. deploy/asoundrc defines mavmic and
+# carries the whole reason: the card's capture stream is 4 channels, and two of
+# them are a unity-gain loopback of everything the workstation plays. plughw
+# downmixes all four, so a TV show woke her with the gain knob at 0. Install
+# that file as ~/.asoundrc on workpc or this device does not resolve.
+#
+# Named CARD=Gen inside mavmic and not card 4, because a USB card number moves
+# when something else is replugged and this daemon must not change ears quietly.
 # Not "default" either: that follows whatever pipewire last decided.
 #
-# plughw and not hw. mavwaked asks arecord for 16kHz mono, which is what the
-# whole pipeline is canonical in. Neither microphone offers it, so bare hw
-# dies on "Channels count non available" before a frame is read. plughw puts
-# ALSA's downmix and resampler in front. Any replacement wants the same.
+# mavmic is a plug device and not hw. mavwaked asks arecord for 16kHz mono,
+# which is what the whole pipeline is canonical in. Neither microphone offers
+# it, so bare hw dies on "Channels count non available" before a frame is read.
+# Any replacement wants ALSA's resampler in front the same way.
 #
-# The Scarlett measured RMS 0.003 against 0.14 on the onboard input, so its
-# front-panel gain is the thing to raise if she mishears. That is a knob, not
-# a control ALSA exposes. The two loud devices, the onboard ALC897 and the
-# camera, both clip at peak 1.0 and are worse candidates, not better ones.
+# The mic is on the XLR, which is Analogue 2 on this card and not Analogue 1:
+# Air and 48V are both named for Line In 2 and both belong to a mic preamp.
+# Measured 2026-08-09 through mavmic at 16kHz mono, gain up: rms 0.01826 peak
+# 0.09290 spoken, against a 0.00031 preamp floor, and 0.00002 for the whole
+# stream with a show playing. Front-panel gain is still the thing to raise if
+# she mishears, and it is a knob, not a control ALSA exposes.
 Environment=LD_LIBRARY_PATH=%h/.local/lib
 ExecStart=%h/.local/bin/mavwaked \
-  -device plughw:CARD=Gen,DEV=0 \
+  -device mavmic \
   -addr 127.0.0.1:9100 \
   -lang ru \
   -vad-model %h/.local/share/maven/models/silero_vad.onnx \