1 files changed, 185 insertions, 0 deletions
diff --git a/stacks/crdop/lib/sound_proxy.py b/stacks/crdop/lib/sound_proxy.py
new file mode 100644
index 0000000..de9b71d
--- /dev/null
+++ b/stacks/crdop/lib/sound_proxy.py
@@ -0,0 +1,185 @@
+"""
+MAX25 sound-proxy — host audio capture/playback.
+
+Linux/KLinux: ALSA (arecord/aplay).
+FreeBSD: OSS via sound_proxy_oss (sox or /dev/dsp).
+"""
+from __future__ import annotations
+
+import os
+import shutil
+import subprocess
+import sys
+import threading
+from dataclasses import dataclass
+from pathlib import Path
+from typing import Callable, Optional, Protocol, runtime_checkable
+
+
+@dataclass
+class SoundConfig:
+    capture: str = "default"
+    playback: str = "default"
+    sample_rate: int = 48000
+    channels: int = 1
+    period_frames: int = 256
+    forbid_pulse: bool = True
+    backend: str = ""  # alsa | oss — empty = auto from platform
+
+
+@runtime_checkable
+class SoundProxyProto(Protocol):
+    def start_capture(self) -> None: ...
+    def read_capture(self, nbytes: int) -> bytes: ...
+    def play_pcm(self, pcm: bytes) -> None: ...
+    def sniff_loop(
+        self,
+        chunk_symbols: int,
+        on_pcm: Callable[[bytes], None],
+        stop: Optional[threading.Event] = None,
+    ) -> None: ...
+    def close(self) -> None: ...
+
+
+def _detect_backend(cfg: SoundConfig) -> str:
+    explicit = (cfg.backend or os.environ.get("MAX25_AUDIO_BACKEND", "")).strip().lower()
+    if explicit in ("alsa", "oss"):
+        return explicit
+    if sys.platform.startswith("freebsd"):
+        return "oss"
+    return "alsa"
+
+
+def create_sound_proxy(cfg: SoundConfig) -> SoundProxyProto:
+    backend = _detect_backend(cfg)
+    if backend == "oss":
+        from sound_proxy_oss import OssSoundConfig, OssSoundProxy
+
+        cap = cfg.capture if cfg.capture not in ("", "default") else "/dev/dsp"
+        pb = cfg.playback if cfg.playback not in ("", "default") else cap
+        return OssSoundProxy(
+            OssSoundConfig(
+                capture=cap,
+                playback=pb,
+                sample_rate=cfg.sample_rate,
+                channels=cfg.channels,
+            )
+        )
+    return AlsaSoundProxy(cfg)
+
+
+class AlsaSoundProxy:
+    def __init__(self, cfg: SoundConfig) -> None:
+        self.cfg = cfg
+        self._rec_proc: Optional[subprocess.Popen[bytes]] = None
+        self._play_proc: Optional[subprocess.Popen[bytes]] = None
+        self._stop = threading.Event()
+
+    def _alsa_env(self) -> dict[str, str]:
+        env = os.environ.copy()
+        if self.cfg.forbid_pulse:
+            env.pop("PULSE_SERVER", None)
+            env.pop("PIPEWIRE_RUNTIME_DIR", None)
+            env["PULSE_SERVER"] = ""
+        return env
+
+    @staticmethod
+    def _check_device(name: str) -> None:
+        low = name.lower()
+        if low in ("default", "pulse", "pipewire") or "pulse" in low or "pipewire" in low:
+            raise ValueError(
+                f"audio device {name!r} not allowed — use hw: or plughw: (kernel ALSA)"
+            )
+
+    def start_capture(self) -> None:
+        if not shutil.which("arecord"):
+            raise RuntimeError("arecord not found — install alsa-utils")
+        self._check_device(self.cfg.capture)
+        cmd = [
+            "arecord",
+            "-q",
+            "-D",
+            self.cfg.capture,
+            "-f",
+            "S16_LE",
+            "-r",
+            str(self.cfg.sample_rate),
+            "-c",
+            str(self.cfg.channels),
+            "-t",
+            "raw",
+        ]
+        self._rec_proc = subprocess.Popen(
+            cmd,
+            stdout=subprocess.PIPE,
+            stderr=subprocess.DEVNULL,
+            env=self._alsa_env(),
+        )
+
+    def read_capture(self, nbytes: int) -> bytes:
+        if self._rec_proc is None or self._rec_proc.stdout is None:
+            return b""
+        return self._rec_proc.stdout.read(nbytes) or b""
+
+    def play_pcm(self, pcm: bytes) -> None:
+        if not pcm:
+            return
+        if not shutil.which("aplay"):
+            raise RuntimeError("aplay not found — install alsa-utils")
+        self._check_device(self.cfg.playback)
+        cmd = [
+            "aplay",
+            "-q",
+            "-D",
+            self.cfg.playback,
+            "-f",
+            "S16_LE",
+            "-r",
+            str(self.cfg.sample_rate),
+            "-c",
+            str(self.cfg.channels),
+            "-t",
+            "raw",
+        ]
+        subprocess.run(
+            cmd,
+            input=pcm,
+            check=False,
+            env=self._alsa_env(),
+            stdout=subprocess.DEVNULL,
+            stderr=subprocess.DEVNULL,
+        )
+
+    def sniff_loop(
+        self,
+        chunk_symbols: int,
+        on_pcm: Callable[[bytes], None],
+        stop: Optional[threading.Event] = None,
+    ) -> None:
+        stop_ev = stop or self._stop
+        frame_bytes = (self.cfg.sample_rate // 1200) * 2 * chunk_symbols
+        self.start_capture()
+        try:
+            while not stop_ev.is_set():
+                chunk = self.read_capture(frame_bytes)
+                if not chunk:
+                    break
+                on_pcm(chunk)
+        finally:
+            self.close()
+
+    def close(self) -> None:
+        self._stop.set()
+        for proc in (self._rec_proc, self._play_proc):
+            if proc is not None and proc.poll() is None:
+                proc.terminate()
+                try:
+                    proc.wait(timeout=1.0)
+                except subprocess.TimeoutExpired:
+                    proc.kill()
+        self._rec_proc = None
+        self._play_proc = None
+
+
+# Backward-compatible alias
+SoundProxy = AlsaSoundProxy