Hooked audio mirroring played back pitch-shifted on games we inject into
that render at a non-device sample rate (e.g. Godot/Brotato render 44100 Hz
on a 48000 Hz endpoint via WASAPI AUTOCONVERTPCM). We attach to an
already-running game, so the render-hook never saw its IAudioClient::
Initialize and assumed the device mix format -- right channels/bits, wrong
rate -- so 44100 audio was rendered as 48000 (+~1.5 semitones).
Fix: treat a pre-existing client's format as a guess and measure its true
sample rate from the render cadence (frames/sec over a steady-state window,
snapped to the nearest standard rate) before publishing it, deferring
capture until verified. Discard the first measurement window so the
buffer-fill burst at attach time doesn't over-count. Streams created after
we inject still carry their exact Initialize format.
Channels/bit-depth genuinely can't be recovered for a pre-existing client:
AUTOCONVERTPCM hands GetBuffer a fixed staging buffer (no buffer stride to
measure -- confirmed empirically) and WASAPI exposes no API for the format.
They stay the device-mix guess, which is correct for the common case
(engines render stereo float, matching the endpoint). To keep a wrong guess
safe, a VirtualQuery clamp stops the capture copy from ever over-reading the
source buffer when the guessed bytes/frame is too large.
Surface all of this: a per-stream AudioFormatState (known / measuring /
measured rate (ch/bits assumed)) in HookStatus, shown in the Audio panel for
the hooked path and as "device endpoint (known)" for loopback; clear hook
logs; and enriched mirror status strings. Documented in README (Limitations
+ Lessons learned). The loopback fallback was always correct (post-mix at
the device format).
Tests: extract a shared, configurable ToneSource (used by coop_tone and the
hook self-test); coop_tone takes rate/channels/bits/format args. Rewrite
audio_hook_test to a format matrix x both code paths -- see-init (exact) and
guess (rate measured) -- plus a byte-incompatible guess that asserts the
clamp keeps capture safe. The matrix caught the attach-burst over-count.
audio_loopback_test now spawns coop_tone at several source formats to
confirm loopback is format-agnostic. 11/11 x64 + 3/3 x86 pass.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Implements the WASAPI render-hook (hook/src/audio_hook.{hpp,cpp}) and an
in-process self-test that proves COM vtable discovery and GetBuffer/ReleaseBuffer
interception with no game and no second Steam account.
- audio_hook.cpp: anchors on IMMDevice::Activate (idx 3) off our own default
endpoint (shared vtable), then hooks IAudioClient::Initialize (3) /
GetService (14) and IAudioRenderClient::GetBuffer (3) / ReleaseBuffer (4) off
live game pointers. Copies primary-stream frames into the audio ring and
releases with AUDCLNT_BUFFERFLAGS_SILENT (+ memset belt-and-suspenders), only
while the host-owned capture_enabled flag is set. Stream counting runs always;
on a ring overrun it keeps playing locally rather than going silent.
- ipc_client.hpp: publish_audio_stream / note_audio_frames /
set_audio_streams_seen write the render-stream debug fields into HookStatus.
- tests/audio_hook_test.cpp: installs the hooks, renders a tone through WASAPI
in-process, and asserts exactly one stream, frames pushed to the ring, the
ring carries the non-silent tone, and the primary was silenced. PASS:
streams_seen=1, frames_captured=32640.
- plan doc: correct GetService vtable index 13 -> 14 (SetEventHandle is 13).
coop_hook DLL wiring + host consumer/fallback come next (M3).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
