Per-player (P1/P2) guitar input conditioning settings

[Cheesewizard]

Summary

Give Player 1 and Player 2 independent guitar-input conditioning settings (Input gain, Noise gate, Compressor, Hum filter, Rocksmith gate) in the in-game Audio Bridge overlay's Guitar tab.

Current state

• The bridge already runs two input routes: route 0 = P1, route 1 = P2 (AsioHook.cpp:1223; mapping also used in DropPedal.cpp).
• The conditioner chain (Hum filter -> Noise gate -> Compressor -> Input gain) is global and P1-only: single atomics + single DSP objects (g_inputGainLinear, g_gateThresholdLinear, g_compressorStrength, g_humFilterBaseHz, g_noiseGate, g_compressor, g_inputLowpass), and the whole block is gated by if (routeIndex == 0 ...) at AsioHook.cpp:1148.
• Net result: Player 2's input currently gets zero conditioning. The setters (AsioHook.hpp:31-54) take no route index, so there is no way to address P2.
• The "Rocksmith gate" control (op 23) overrides the game's own P1_NoiseFloor calibration (SharedOutput.cpp:234), not our conditioner. The game has a P2_NoiseFloor counterpart.

Design decision

Key per-player settings by physical input route (route 0 = P1, route 1 = P2), not by game profile. The conditioner compensates for physical-input characteristics (a quiet interface input, a ground-loop hum on that cable); profile-mapping would need a fragile game hook and is not guaranteed 1:1. The only control with a genuine native P1/P2 twin is the Rocksmith-gate override (P1_NoiseFloor / P2_NoiseFloor).

Wire protocol

Extend ops 15/19/20/23/24 to accept an optional leading <player>, field, defaulting to route 0 when absent (backward-compatible, no new op numbers):

• 15 gain: "<player>,<tenths>"
• 19 gate: "<player>,<tenths>"
• 20 compressor: "<player>,<pct>"
• 24 hum: "<player>,<hz>"
• 23 Rocksmith gate: "<player>,<on>,<tenths>"

Implementation checklist

• DLL/Audio/AsioHook.cpp (core): turn the four conditioner atomics (35, 42, 49, 56) into [INPUT_ROUTE_COUNT] arrays; make g_noiseGate (523), g_compressor (643), g_inputLowpass and the hum-notch state per-route arrays (required - these are stateful envelope/biquad followers and the two routes interleave on the audio thread); give the Process*InPlace helpers a route/instance param; remove the routeIndex == 0 gate at 1148 and index every g_* load by routeIndex; add size_t routeIndex to the setters/getters (1773-1851).
• DLL/Audio/AsioHook.hpp: update the five setter/getter signatures (31-54) to take routeIndex.
• DLL/Audio/SharedOutput.cpp: parse the optional leading <player>, in op cases 15/19/20/23/24 (~222-249), clamp to [0, INPUT_ROUTE_COUNT), pass through.
• DLL/Menu.cpp (overlay Guitar tab, 287-338): duplicate the seed vars (246-250) into [2] arrays; add a P1/P2 SegmentedControl shown only when GameState::IsMultiplayer() (same showPlayerTwo gate as the input-2 meter at 271); prefix the player index into every BridgeControl payload.
• Persistence - add P2 keys: DLL/Settings.cpp (150-155 defaults, 282-287 reader); DLL/ModManager.cpp seeding (588-640) + launch-active check (166-167); GUI/ReadSettings.cs identifiers + GUI/WriteSettings.cs default-ini rows (227-232); optionally GUI/Audio/AudioRoutingPanel.cs desktop controls for parity.
• Rocksmith-gate P2 (deferrable, needs native reversing): RocksmithGate::SetOverride/ApplyPerFrame write P1_NoiseFloor; add a per-player pair targeting P2_NoiseFloor. If deferred, grey out the P2 "Rocksmith gate" row with a tooltip.

Notes / risk

• Feature-off path stays bit-exact (every stage no-ops on 0/unity).
• P2 gets zero conditioning today, so nothing regresses for existing P1 users.
• The four Get*Db getters have no external callers, so per-route conversion is low-impact.

Open questions

1. Desktop GUI parity - expose the P2 set in AudioRoutingPanel too, or in-game overlay only?
2. Rocksmith-gate P2 - ship now (locate P2_NoiseFloor) or defer and grey out that one row?
3. Single-player - hide the P1/P2 selector entirely (default), or always show it?