diff --git a/sync_audio_test.py b/sync_audio_test.py
index 8519adc..87dc77a 100644
--- a/sync_audio_test.py
+++ b/sync_audio_test.py
@@ -59,6 +59,25 @@ def decimate_for_plot(arr: np.ndarray, max_pts: int = 120_000) -> tuple[np.ndarr
     stride = int(math.ceil(len(arr) / max_pts))
     return arr[::stride], stride
 
+def decimate_with_peak(arr: np.ndarray, peak_idx: int, max_pts: int = 200_000) -> tuple[np.ndarray, np.ndarray]:
+    """Decimate array for plotting using max-pooling to preserve all peaks."""
+    n = len(arr)
+    if n <= max_pts:
+        return arr, np.arange(n, dtype=np.float64)
+    stride = int(math.ceil(n / max_pts))
+    abs_arr = np.abs(arr)
+    n_blocks = (n + stride - 1) // stride
+    out = np.empty(n_blocks, dtype=arr.dtype)
+    idx_out = np.empty(n_blocks, dtype=np.float64)
+    for i in range(n_blocks):
+        start = i * stride
+        end = min(start + stride, n)
+        block_abs = abs_arr[start:end]
+        local_peak = int(np.argmax(block_abs))
+        out[i] = arr[start + local_peak]
+        idx_out[i] = float(start + local_peak)
+    return out, idx_out
+
 
 def find_wavs_from_config(cfg: dict) -> tuple[str, str, int, float, float]:
     audio_cfg = cfg.get("audio", {})
@@ -128,13 +147,14 @@ class SyncWindow(QtWidgets.QMainWindow):
         # xcorr display — corr is already fftshifted
         N = len(self.corr)
         # lags in seconds for display
-        # raw corr was shifted: center at N//2, range [- (len(b)-1) .. len(a)-1]
-        # for display we map indices to lag
         total = len(self.a) + len(self.b) - 1
         n_pow2 = N
         # shifted lags: -N//2 .. N//2-1
         self.corr_lags = np.arange(N) - N//2
         self.corr_lags_sec = self.corr_lags / sr
+        # find peak index in raw (unshifted) for decimation
+        peak_raw_idx = int(np.argmax(np.abs(self.corr)))  # this is fftshifted, peak near center
+        # for decimation we need the index in the shifted array
 
         central = QtWidgets.QWidget()
         self.setCentralWidget(central)
@@ -169,9 +189,10 @@ class SyncWindow(QtWidgets.QMainWindow):
         self.p3 = self.gw.addPlot(row=2, col=0, title="Cross-correlation (GCC-PHAT)" if method=="phat" else "Cross-correlation")
         self.p3.showGrid(x=True, y=True)
         self.p3.setLabel("bottom", "Lag", "s")
-        # decimate corr for perf if huge
-        corr_dec, corr_stride = decimate_for_plot(self.corr, max_pts=200_000)
-        corr_lags_dec = self.corr_lags_sec[::corr_stride] if corr_stride>1 else self.corr_lags_sec
+        # decimate corr with peak awareness
+        peak_in_shifted = int(np.argmax(np.abs(self.corr)))
+        corr_dec, corr_idx = decimate_with_peak(self.corr, peak_in_shifted, max_pts=200_000)
+        corr_lags_dec = self.corr_lags_sec[corr_idx.astype(int)]
         self.curve_corr = self.p3.plot(corr_lags_dec, np.abs(corr_dec), pen=pg.mkPen("#ffd166", width=1))
         self.peak_line = pg.InfiniteLine(pos=self.lag_sec, angle=90, pen=pg.mkPen("#06d6a0", width=2, style=QtCore.Qt.PenStyle.DashLine))
         self.p3.addItem(self.peak_line)
@@ -213,6 +234,9 @@ class SyncWindow(QtWidgets.QMainWindow):
         btn_swap = QtWidgets.QPushButton("Swap A/B")
         ctr.addWidget(btn_swap)
 
+        btn_export = QtWidgets.QPushButton("Export data")
+        ctr.addWidget(btn_export)
+
         # volume + playback
         ctr2 = QtWidgets.QHBoxLayout()
         lay.addLayout(ctr2)
@@ -249,6 +273,7 @@ class SyncWindow(QtWidgets.QMainWindow):
         self.vol.valueChanged.connect(lambda v: self.vol_label.setText(f"{v}%"))
         btn_auto.clicked.connect(self.on_auto)
         btn_swap.clicked.connect(self.on_swap)
+        btn_export.clicked.connect(self.on_export)
         self.btn_play_a.clicked.connect(lambda: self.play("a"))
         self.btn_play_b.clicked.connect(lambda: self.play("b"))
         self.btn_play_mix.clicked.connect(lambda: self.play("mix"))
@@ -321,6 +346,53 @@ class SyncWindow(QtWidgets.QMainWindow):
         self.corr = corr
         self._set_lag(lag/self.sr, "swap")
 
+    def on_export(self):
+        import json
+        path, _ = QtWidgets.QFileDialog.getSaveFileName(
+            self, "Export sync data", "sync_data.json", "JSON (*.json)")
+        if not path:
+            return
+        # export decimated correlation (full res is too large)
+        peak_in_shifted = int(np.argmax(np.abs(self.corr)))
+        corr_dec, corr_idx = decimate_with_peak(self.corr, peak_in_shifted, max_pts=200_000)
+        corr_lags_sec = self.corr_lags_sec[corr_idx.astype(int)]
+        export = {
+            "file_a": self.a_path,
+            "file_b": self.b_path,
+            "sr": self.sr,
+            "method": self.method,
+            "device": self.device_pref,
+            "lag_samples": self.lag_samples,
+            "lag_sec": self.lag_sec,
+            "peak_value": float(self.peak),
+            "a_samples": len(self.a_orig),
+            "a_duration_sec": len(self.a_orig) / self.sr,
+            "b_samples": len(self.b_orig),
+            "b_duration_sec": len(self.b_orig) / self.sr,
+            "corr_peak_index": peak_in_shifted,
+            "corr_length": len(self.corr),
+            # decimated correlation for plotting (not full 4M points)
+            "corr_lags_sec": corr_lags_sec.tolist(),
+            "corr_magnitude": np.abs(corr_dec).tolist(),
+            # waveform stats (full res waveforms too large for JSON)
+            "a_stats": {
+                "mean": float(self.a_orig.mean()),
+                "std": float(self.a_orig.std()),
+                "min": float(self.a_orig.min()),
+                "max": float(self.a_orig.max()),
+            },
+            "b_stats": {
+                "mean": float(self.b_orig.mean()),
+                "std": float(self.b_orig.std()),
+                "min": float(self.b_orig.min()),
+                "max": float(self.b_orig.max()),
+            },
+        }
+        with open(path, "w") as f:
+            json.dump(export, f, indent=2)
+        print(f"exported to {path}")
+        self.setWindowTitle(f"movie_sync — exported to {os.path.basename(path)}")
+
     def play(self, which: str):
         if not HAS_SD:
             return