Add test file that captures microphone audio

uses the same code that the LVA uses to capture microphone audio. Defaults to downmix and accepts left and right as variable for --channel.

tests/lva_mic_capture.py

@@ -0,0 +1,73 @@
+import argparse
+import soundcard as sc
+import numpy as np
+import wave
+
+DEVICE = "reSpeaker XVF3800 4-Mic Array Analog Stereo"
+SECONDS = 5
+SR = 16000
+BLOCK = 1024
+
+def main():
+    parser = argparse.ArgumentParser(description="Record from soundcard mic to WAV.")
+    parser.add_argument(
+        "--channel",
+        choices=["mix", "left", "right"],
+        default="mix",
+        help="mix=record 1ch (downmix/default). left/right=record 2ch and select.",
+    )
+    parser.add_argument("--seconds", type=int, default=SECONDS)
+    parser.add_argument("--device", type=str, default=DEVICE)
+    parser.add_argument("--out", type=str, default="/tmp/lva_soundcard.wav")
+    args = parser.parse_args()
+
+    if args.channel == "mix":
+        in_ch = 1
+        out_ch = 1
+        out_path = args.out
+    else:
+        in_ch = 2
+        out_ch = 1
+        # If user didn't override --out, make filename reflect selection
+        if args.out == "/tmp/lva_soundcard.wav":
+            out_path = f"/tmp/lva_soundcard_{args.channel}.wav"
+        else:
+            out_path = args.out
+
+    mic = sc.get_microphone(args.device, include_loopback=False)
+    print("Using mic:", mic.name)
+    print(f"Mode: {args.channel} (request channels={in_ch} -> write channels={out_ch})")
+
+    frames = []
+    with mic.recorder(samplerate=SR, channels=in_ch, blocksize=BLOCK) as r:
+        for _ in range(int(SR * args.seconds / BLOCK)):
+            buf = r.record(BLOCK)
+
+            if in_ch == 1:
+                # buf can be (BLOCK,) or (BLOCK, 1) depending on backend
+                mono = buf.reshape(-1)
+                sample = mono
+            else:
+                # buf should be (BLOCK, 2)
+                if buf.ndim != 2 or buf.shape[1] < 2:
+                    raise RuntimeError(f"Expected stereo buffer, got shape {buf.shape}")
+                idx = 0 if args.channel == "left" else 1
+                sample = buf[:, idx]
+
+            rms = float(np.sqrt(np.mean(np.square(sample)))) if sample.size else 0.0
+            print(f"rms={rms:.6f}")
+
+            pcm16 = (np.clip(sample, -1.0, 1.0) * 32767.0).astype("<i2")
+            frames.append(pcm16.tobytes())
+
+    with wave.open(out_path, "wb") as wf:
+        wf.setnchannels(out_ch)
+        wf.setsampwidth(2)
+        wf.setframerate(SR)
+        wf.writeframes(b"".join(frames))
+
+    print("Wrote:", out_path)
+
+if __name__ == "__main__":
+    main()
+