Initial scaffold: Pi Multi-FX Pedal with NAM A2, IR cab, multi-FX, MIDI, stomp UI

src/dsp/nam_host.py

@@ -0,0 +1,97 @@
+"""NAM A2 model host — load, configure, and run inference on RPi 4B.
+
+Leverages `neural-amp-modeler` (nam) Python package or the NAM LV2 plugin
+for real-time inference on the Raspberry Pi 4B.
+"""
+
+from __future__ import annotations
+
+import logging
+from dataclasses import dataclass, field
+from pathlib import Path
+from typing import Optional
+
+import numpy as np
+
+logger = logging.getLogger(__name__)
+
+DEFAULT_NAM_DIR = Path.home() / ".pedal" / "nam"
+DEFAULT_LV2_MODEL_DIR = Path.home() / ".lv2" / "nam-models"
+
+
+@dataclass
+class NAMModel:
+    """Metadata for a loaded NAM model."""
+    name: str
+    path: str
+    size_mb: float
+    sample_rate: int = 48000
+    latency_samples: int = 0
+    compatible: bool = True
+
+
+class NAMHost:
+    """Hosts NAM models for real-time amp simulation.
+
+    On RPi 4B, this delegates to either:
+    1. The NAM LV2 plugin (via JACK/Carla) — for production use
+    2. The nam Python package — for testing/development
+    """
+
+    def __init__(
+        self,
+        models_dir: str | Path = DEFAULT_NAM_DIR,
+        lv2_dir: str | Path = DEFAULT_LV2_MODEL_DIR,
+        use_lv2: bool = True,
+    ):
+        self._models_dir = Path(models_dir)
+        self._lv2_dir = Path(lv2_dir)
+        self._use_lv2 = use_lv2
+        self._loaded_model: Optional[NAMModel] = None
+        self._models_dir.mkdir(parents=True, exist_ok=True)
+
+    def load_model(self, model_path: str) -> bool:
+        """Load a NAM model file into the inference engine."""
+        path = Path(model_path)
+        if not path.exists() or path.suffix not in (".nam",):
+            logger.error("Model not found or invalid: %s", model_path)
+            return False
+
+        size_mb = path.stat().st_size / (1024 * 1024)
+        is_feather = size_mb < 10
+
+        self._loaded_model = NAMModel(
+            name=path.stem,
+            path=str(path),
+            size_mb=size_mb,
+            compatible=is_feather,
+        )
+
+        # Symlink for LV2 plugin access
+        if self._use_lv2:
+            self._lv2_dir.mkdir(parents=True, exist_ok=True)
+            link = self._lv2_dir / path.name
+            if link.exists() or link.is_symlink():
+                link.unlink()
+            link.symlink_to(path.absolute())
+
+        logger.info(
+            "Loaded NAM model: %s (%.1f MB, %s)",
+            self._loaded_model.name,
+            size_mb,
+            "compatible" if is_feather else "may cause xruns",
+        )
+        return True
+
+    def unload(self) -> None:
+        """Unload the current NAM model."""
+        self._loaded_model = None
+        logger.info("NAM model unloaded")
+
+    @property
+    def is_loaded(self) -> bool:
+        return self._loaded_model is not None
+
+    @property
+    def current_model(self) -> Optional[NAMModel]:
+        return self._loaded_model