Mixer engine: output routing, full state restore, MIDI learn API, PipeWire multi-channel support

src/MixerEngine.hpp

@@ -11,6 +11,7 @@
 #include <functional>
 #include "MixerChannelStrip.hpp"
 #include "MixerBus.hpp"
+#include "MidiMapper.hpp"
 
 namespace pipedal {
 
@@ -70,6 +71,11 @@ public:
     /// Returns a pointer to the new channel (valid until removed).
     MixerChannelStrip* addChannel(int physicalInputIndex);
 
+    /// Auto-create channels based on the number of detected input channels.
+    /// Removes existing channels and creates one strip per input.
+    /// Also sets up default output routes.
+    void autoCreateChannels(uint32_t inputChannelCount);
+
     /// Remove a channel by its channel index.
     void removeChannel(int channelIndex);
 
@@ -113,6 +119,32 @@ public:
     /// Clear all routes.
     void clearRoutes();
 
+    /// --- Output Routing ---
+
+    /// Describes a mapping from a mixer bus to physical output channels.
+    /// Multiple routes can be active simultaneously (e.g. Master→1-2, Aux1→3-4).
+    struct MixerOutputRoute {
+        int64_t sourceBusId;      // Bus to route from
+        int sourceStartChannel;   // Starting channel on the bus (0=L, 1=R)
+        int targetStartChannel;   // Starting physical output channel
+        int channels;             // Number of consecutive channels to route (1 or 2 typically)
+    };
+
+    /// Get the current output routing table (bus → physical output channel mapping).
+    const std::vector<MixerOutputRoute>& outputRoutes() const { return outputRoutes_; }
+
+    /// Set the entire output routing table.
+    void setOutputRoutes(const std::vector<MixerOutputRoute>& routes);
+
+    /// Add a single output route.
+    void addOutputRoute(int64_t busId, int sourceStartChannel, int targetStartChannel, int channels);
+
+    /// Remove all output routes for a given bus.
+    void removeOutputRoutes(int64_t busId);
+
+    /// Get all routes for a given bus.
+    std::vector<MixerOutputRoute> findOutputRoutesForBus(int64_t busId) const;
+
     /// Get all current routes.
     const std::vector<MixerRouteEntry>& routes() const { return routes_; }
 
@@ -143,6 +175,16 @@ public:
     /// True if any channel has solo engaged.
     bool anySoloActive() const;
 
+    /// --- MIDI Control Surface Mapping ---
+
+    /// Access the MIDI mapper for CC control surface mapping.
+    MidiMapper& midiMapper() { return midiMapper_; }
+    const MidiMapper& midiMapper() const { return midiMapper_; }
+
+    /// Process a MIDI event (typically from the real-time audio thread).
+    /// Routes CC messages to the midi mapper. Returns true if consumed.
+    bool processMidiEvent(const struct MidiEvent& event);
+
     /// --- State Serialization ---
 
     struct MixerSnapshot {
@@ -181,6 +223,9 @@ private:
     // Routing entries
     std::vector<MixerRouteEntry> routes_;
 
+    // Output routing entries (bus → physical output channel mapping)
+    std::vector<MixerOutputRoute> outputRoutes_;
+
     // Audio configuration
     uint32_t sampleRate_ = 48000;
     size_t maxBufferSize_ = 512;
@@ -188,6 +233,9 @@ private:
     // IHost reference for FX preparation
     IHost* pHost_ = nullptr;
 
+    // MIDI CC control surface mapper
+    MidiMapper midiMapper_;
+
     // Next bus ID counter
     static std::atomic<int64_t> nextBusId_;