Nuova tab Registra: cattura audio da ingresso del computer

Aggiunta sezione per registrare in MP3 320 kbps da qualsiasi
dispositivo di input audio del sistema (mixer, scheda audio
esterna, microfono interno, BlackHole / driver virtuali per audio
di sistema).

- core/recorder.py: list_input_devices() parsa l'output di
  ffmpeg -list_devices su AVFoundation (macOS) e DirectShow (Win),
  marca come 'virtual' i driver loopback noti (BlackHole, Soundflower,
  Loopback, VB-Cable, Stereo Mix, OBS). start_recording() lancia
  ffmpeg in thread e emette eventi tick/started/stopped/error.
- api/bridge.py: list_audio_inputs, start_audio_recording,
  stop_audio_recording, is_audio_recording
- webui: hero rosso, dropdown dispositivi con badge 'loopback',
  selettore bitrate, timer HH:MM:SS animato, bottone REC con
  pulse animation, card 'Ultima registrazione' con durata+path
- Hint visibile: per registrare audio di sistema serve BlackHole

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

core/recorder.py

@@ -0,0 +1,308 @@
+"""Registrazione audio da un dispositivo di input via ffmpeg.
+
+macOS: usa AVFoundation (ingresso fisico + driver virtuali tipo BlackHole)
+Windows: usa DirectShow
+"""
+
+from __future__ import annotations
+
+import os
+import re
+import subprocess
+import sys
+import threading
+import time
+from pathlib import Path
+from typing import Callable, Optional
+
+from core.paths import find_ffmpeg
+
+
+_IS_MAC = sys.platform == "darwin"
+_IS_WIN = sys.platform == "win32"
+
+
+# ============================================================
+# Stato globale (un solo recording alla volta)
+# ============================================================
+_current_proc: Optional[subprocess.Popen] = None
+_proc_lock = threading.Lock()
+_stop_event = threading.Event()
+_recording_thread: Optional[threading.Thread] = None
+
+
+def is_recording() -> bool:
+    with _proc_lock:
+        return _current_proc is not None and _current_proc.poll() is None
+
+
+# ============================================================
+# Lista dispositivi
+# ============================================================
+def list_input_devices() -> list[dict]:
+    """Ritorna la lista dei dispositivi audio di input.
+    Ogni voce: {"id": "0", "name": "...", "is_virtual": bool}.
+
+    is_virtual = True per driver di loopback noti (BlackHole, Soundflower,
+    Loopback, Audio Hijack, VB-Cable, ...)
+    """
+    ffmpeg = find_ffmpeg()
+    if not ffmpeg:
+        return []
+
+    if _IS_MAC:
+        return _list_macos(ffmpeg)
+    if _IS_WIN:
+        return _list_windows(ffmpeg)
+    return []
+
+
+_VIRTUAL_KEYWORDS = (
+    "blackhole", "soundflower", "loopback", "audio hijack",
+    "vb-cable", "vb-audio", "stereo mix", "what u hear",
+    "obs", "system audio",
+)
+
+
+def _is_virtual(name: str) -> bool:
+    n = (name or "").lower()
+    return any(k in n for k in _VIRTUAL_KEYWORDS)
+
+
+def _list_macos(ffmpeg: str) -> list[dict]:
+    """Parsa l'output di `ffmpeg -f avfoundation -list_devices true -i ""`.
+    L'output va su stderr."""
+    try:
+        proc = subprocess.run(
+            [ffmpeg, "-hide_banner", "-f", "avfoundation",
+             "-list_devices", "true", "-i", ""],
+            capture_output=True, text=True, timeout=10,
+        )
+    except Exception:
+        return []
+
+    devices: list[dict] = []
+    in_audio = False
+    audio_section_re = re.compile(r"AVFoundation\s+audio\s+devices", re.IGNORECASE)
+    other_section_re = re.compile(r"AVFoundation\s+(?:video)\s+devices", re.IGNORECASE)
+    line_re = re.compile(r"\[(\d+)\]\s+(.+?)\s*$")
+
+    for raw in proc.stderr.splitlines():
+        line = raw.strip()
+        if audio_section_re.search(line):
+            in_audio = True
+            continue
+        if other_section_re.search(line):
+            in_audio = False
+            continue
+        if not in_audio:
+            continue
+        clean = re.sub(r"^\[AVFoundation[^\]]*\]\s*", "", line)
+        m = line_re.match(clean)
+        if not m:
+            continue
+        idx, name = m.group(1), m.group(2).strip()
+        devices.append({"id": idx, "name": name, "is_virtual": _is_virtual(name)})
+
+    return devices
+
+
+def _list_windows(ffmpeg: str) -> list[dict]:
+    """Parsa l'output di `ffmpeg -f dshow -list_devices true -i dummy`."""
+    try:
+        proc = subprocess.run(
+            [ffmpeg, "-hide_banner", "-f", "dshow",
+             "-list_devices", "true", "-i", "dummy"],
+            capture_output=True, text=True, timeout=10,
+        )
+    except Exception:
+        return []
+
+    devices: list[dict] = []
+    in_audio = False
+    line_re = re.compile(r'"([^"]+)"\s*\((audio|video)\)', re.IGNORECASE)
+    name_re = re.compile(r'"([^"]+)"')
+
+    for raw in proc.stderr.splitlines():
+        line = raw.strip()
+        low = line.lower()
+        if "directshow audio devices" in low:
+            in_audio = True
+            continue
+        if "directshow video devices" in low:
+            in_audio = False
+            continue
+
+        m = line_re.search(line)
+        if m:
+            name, kind = m.group(1), m.group(2).lower()
+            if kind == "audio":
+                devices.append({"id": name, "name": name, "is_virtual": _is_virtual(name)})
+            continue
+
+        if in_audio:
+            mn = name_re.search(line)
+            if mn:
+                name = mn.group(1)
+                devices.append({"id": name, "name": name, "is_virtual": _is_virtual(name)})
+
+    # Dedup preservando l'ordine
+    seen = set()
+    out = []
+    for d in devices:
+        if d["id"] in seen:
+            continue
+        seen.add(d["id"])
+        out.append(d)
+    return out
+
+
+# ============================================================
+# Registrazione
+# ============================================================
+def _build_record_cmd(ffmpeg: str, device_id: str, output_path: str,
+                      bitrate: str) -> list[str]:
+    """Comando ffmpeg per registrare su file MP3."""
+    if _IS_MAC:
+        return [
+            ffmpeg, "-hide_banner", "-y",
+            "-f", "avfoundation",
+            "-i", f":{device_id}",
+            "-acodec", "libmp3lame",
+            "-b:a", bitrate,
+            "-vn",
+            output_path,
+        ]
+    if _IS_WIN:
+        return [
+            ffmpeg, "-hide_banner", "-y",
+            "-f", "dshow",
+            "-i", f"audio={device_id}",
+            "-acodec", "libmp3lame",
+            "-b:a", bitrate,
+            "-vn",
+            output_path,
+        ]
+    raise RuntimeError("Sistema operativo non supportato per la registrazione")
+
+
+def start_recording(
+    device_id: str,
+    output_path: str,
+    bitrate: str = "320k",
+    progress_callback: Optional[Callable] = None,
+) -> dict:
+    """Avvia una registrazione in un thread.
+    Ritorna {ok, error?, output_path?}.
+
+    progress_callback(status, payload) viene chiamato con:
+      ("started",  {"output_path": ...})
+      ("tick",     {"seconds": int})
+      ("stopped",  {"output_path": ..., "seconds": int})
+      ("error",    {"error": "..."})
+    """
+    global _current_proc, _recording_thread
+
+    if is_recording():
+        return {"ok": False, "error": "Una registrazione e gia in corso"}
+
+    ffmpeg = find_ffmpeg()
+    if not ffmpeg:
+        return {"ok": False, "error": "ffmpeg non trovato"}
+
+    out = Path(output_path)
+    out.parent.mkdir(parents=True, exist_ok=True)
+
+    cmd = _build_record_cmd(ffmpeg, device_id, str(out), bitrate)
+
+    _stop_event.clear()
+
+    def _worker():
+        global _current_proc
+        try:
+            with _proc_lock:
+                _current_proc = subprocess.Popen(
+                    cmd,
+                    stdin=subprocess.PIPE,
+                    stdout=subprocess.PIPE,
+                    stderr=subprocess.PIPE,
+                    text=False,  # bytes su stdin per "q"
+                )
+
+            if progress_callback:
+                progress_callback("started", {"output_path": str(out)})
+
+            start = time.monotonic()
+            # Pubblica un tick al secondo
+            while True:
+                if _stop_event.is_set():
+                    break
+                rc = _current_proc.poll()
+                if rc is not None:
+                    break
+                elapsed = int(time.monotonic() - start)
+                if progress_callback:
+                    progress_callback("tick", {"seconds": elapsed})
+                time.sleep(1.0)
+
+            # Stop gracefully
+            if _current_proc.poll() is None:
+                try:
+                    _current_proc.stdin.write(b"q\n")
+                    _current_proc.stdin.flush()
+                except Exception:
+                    pass
+                try:
+                    _current_proc.wait(timeout=5)
+                except subprocess.TimeoutExpired:
+                    _current_proc.terminate()
+                    try:
+                        _current_proc.wait(timeout=3)
+                    except subprocess.TimeoutExpired:
+                        _current_proc.kill()
+
+            rc = _current_proc.returncode
+            seconds = int(time.monotonic() - start)
+
+            with _proc_lock:
+                _current_proc = None
+
+            if progress_callback:
+                if rc == 0 or out.exists():
+                    progress_callback("stopped", {"output_path": str(out), "seconds": seconds})
+                else:
+                    err = ""
+                    try:
+                        err = (_get_last_stderr() or "").strip().splitlines()[-1]
+                    except Exception:
+                        pass
+                    progress_callback("error", {"error": err or f"ffmpeg exit {rc}"})
+        except Exception as e:
+            with _proc_lock:
+                _current_proc = None
+            if progress_callback:
+                progress_callback("error", {"error": str(e)})
+
+    _recording_thread = threading.Thread(target=_worker, daemon=True)
+    _recording_thread.start()
+
+    return {"ok": True, "output_path": str(out)}
+
+
+def _get_last_stderr() -> str:
+    """Tenta di leggere lo stderr residuo del processo corrente."""
+    with _proc_lock:
+        proc = _current_proc
+    if proc is None or proc.stderr is None:
+        return ""
+    try:
+        data = proc.stderr.read() or b""
+        return data.decode("utf-8", errors="ignore")
+    except Exception:
+        return ""
+
+
+def stop_recording() -> dict:
+    """Ferma la registrazione corrente (se attiva)."""
+    _stop_event.set()
+    return {"ok": True}