The Windows virtual mic worked only with manual Sound-settings fiddling: on a
headless host (no real audio output) BOTH the desktop-audio loopback and the
virtual mic must run on virtual cables, and on DIFFERENT ones or the loopback
re-captures the injected mic (echo). The Steam pair gives only one usable cable
(Steam Streaming Speakers loopback is silent — validated), so the mic + loopback
collided and echoed, and when the default playback happened to be the mic device
the anti-echo guard reported the mic "unavailable".
Host now auto-wires the devices at startup (audio/windows/audio_control.rs,
ensure_wired_once, hooked from open_audio_capture/open_virtual_mic): default
playback = a loopback-capable render that is NOT a cable and NOT the dead Steam
Speakers (real output > Steam Streaming Microphone); default recording = the mic
capture (VB-Cable "CABLE Output" preferred). Uses a hand-rolled IPolicyConfig
vtable (the only way to set a default endpoint; not in windows/wasapi crates).
Opt out with PUNKTFUNK_KEEP_DEFAULT. wasapi_mic candidates now prefer "cable
input". Validated live: from a deliberately-wrong start (playback=CABLE Input)
the host corrected both default endpoints at the OS level.
A Windows audio endpoint can only be created by a kernel-mode driver (no UMDF
path — ACX is KMDF-only), so we cannot self-sign our own like the UMDF gamepad/
display drivers. Instead the installer bundles + silently installs the official
base VB-CABLE (VB-Audio donationware, vendor-signed → loads with no test-signing,
redistributed under VB-Audio's bundling grant): install-vbcable.ps1 (seed the
VB-Audio cert into TrustedPublisher, run -i -h) + an installaudiocable task,
gated on -VbCableDir/$env:VBCABLE_DIR (the package binary is not in the repo).
Attribution in packaging/windows/licenses/VB-CABLE-NOTICE.txt. .iss compiles
with the path enabled.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The MIT OR Apache-2.0 SOURCE license is clean (audit found no copied copyleft); the
gaps were all binary-distribution (Layer-2). This makes the shipped artifacts honest:
- Windows host + client: bundled FFmpeg BtbN gpl-shared -> lgpl-shared (AMF/QSV/decode
unaffected; the GPL-only x264/x265 were never used), and ship the FFmpeg LGPL notice
+ license text in the installer + MSIX (licenses/).
- THIRD-PARTY-NOTICES.txt generated + bundled into installer/MSIX/deb/rpm. Offline
generator (scripts/gen-third-party-notices.{py,sh}) + cargo-about config (about.toml/
.hbs) with a permissive-only accepted-license allow-list as a copyleft regression gate.
- Reword the win32u GPU-preference hook comments to reflect independent reimplementation
(no Apollo/Sunshine GPL-3.0 source copied).
- README dual-license + inbound=outbound contributor clause + non-affiliation trademark
disclaimer; new CONTRIBUTING.md.
- LICENSE files into the standalone driver + vk-layer workspaces; deb copyright holder
aligned to "unom and the punktfunk contributors".
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
enricobuehler