fix: apply_sync ffmpeg streamcpy and filter

apply_sync.py

@@ -57,6 +57,23 @@ def probe_audio_streams(path: str) -> list[dict]:
         return []
 
 
+def _codec_args(codec: str, out_idx: int) -> list[str]:
+    """Return ffmpeg codec args for a given audio codec string."""
+    lossless = {"flac", "alac", "pcm_s16le", "pcm_s24le", "pcm_s32le", "pcm_f32le", "pcm_f64le"}
+    if codec in lossless:
+        return [f"-c:a:{out_idx}", codec]
+    # lossy codecs: use original where possible
+    codec_map = {
+        "aac": "aac", "mp3": "libmp3lame", "opus": "libopus",
+        "vorbis": "libvorbis", "ac3": "ac3", "eac3": "eac3",
+    }
+    enc = codec_map.get(codec, "aac")
+    args = [f"-c:a:{out_idx}", enc]
+    if enc != codec or codec not in lossless:
+        args += [f"-b:a:{out_idx}", "192k"]
+    return args
+
+
 def build_ffmpeg_cmd(file_a: str, file_b: str, lag_sec: float, out_path: str) -> list[str]:
     """Build ffmpeg command to mux A video + A audio + delayed B audio streams."""
     b_streams = probe_audio_streams(file_b)
@@ -67,6 +84,7 @@ def build_ffmpeg_cmd(file_a: str, file_b: str, lag_sec: float, out_path: str) ->
     set_german = (len(b_streams) == 1 and b_streams[0]["language"] in ("und", "unknown", ""))
 
     # Build filter_complex for B audio streams
+    # Negative adelay trims the start (B ahead of A), positive adds silence (B behind A)
     filters = []
     for i, s in enumerate(b_streams):
         filters.append(f"[1:a:{i}]adelay={lag_ms:.0f}|{lag_ms:.0f}:all=1[d{i}]")
@@ -81,11 +99,15 @@ def build_ffmpeg_cmd(file_a: str, file_b: str, lag_sec: float, out_path: str) ->
     for i in range(len(b_streams)):
         cmd += ["-map", f"[d{i}]"]
 
-    # Codecs: copy everything (lossless)
-    cmd += ["-c:v", "copy", "-c:a", "copy"]
+    # Codecs: copy video + A's audio, re-encode B's filtered audio with same codec
+    n_a_audio = len(probe_audio_streams(file_a))
+    cmd += ["-c:v", "copy"]
+    for i in range(n_a_audio):
+        cmd += [f"-c:a:{i}", "copy"]
+    for i, s in enumerate(b_streams):
+        cmd += _codec_args(s["codec"], n_a_audio + i)
 
     # Language metadata for B audio streams (they become the last N audio streams in output)
-    n_a_audio = len(probe_audio_streams(file_a))
     for i, s in enumerate(b_streams):
         out_audio_idx = n_a_audio + i  # 0-based index in output audio streams
         if set_german and i == 0:

sync_audio_test.py

@@ -111,7 +111,8 @@ def find_wavs_from_config(cfg: dict) -> tuple[str, str, int, float, float, int]:
 
 class SyncWindow(QtWidgets.QMainWindow):
     def __init__(self, a_path: str, b_path: str, sr: int = 48000, method: str = "phat", device: str = "auto",
-                 video_a: str = "", video_b: str = "", out_dir: str = "output", volume: int = 30):
+                 video_a: str = "", video_b: str = "", out_dir: str = "output", volume: int = 30,
+                 duration: float = 90.0):
         super().__init__()
         self.setWindowTitle(f"movie_sync — audio sync test — {device_info()}")
         self.resize(1400, 900)
@@ -121,6 +122,7 @@ class SyncWindow(QtWidgets.QMainWindow):
         self.video_b = video_b
         self.out_dir = out_dir
         self.sr = sr
+        self.duration = duration
         self.method = method
         self.device_pref = device
         self._updating = False
@@ -193,6 +195,10 @@ class SyncWindow(QtWidgets.QMainWindow):
         self.p3.addItem(self.peak_line)
         self.p3.setXRange(self.lag_sec-2, self.lag_sec+2)
 
+        self.xcorr_val_label = QtWidgets.QLabel()
+        self.xcorr_val_label.setStyleSheet("color: #ffd166; font-size: 12px;")
+        lay.addWidget(self.xcorr_val_label)
+
         # controls
         ctr = QtWidgets.QHBoxLayout()
         lay.addLayout(ctr)
@@ -232,7 +238,7 @@ class SyncWindow(QtWidgets.QMainWindow):
         btn_export = QtWidgets.QPushButton("Export data")
         ctr.addWidget(btn_export)
 
-        btn_verify = QtWidgets.QPushButton("Verify (30s)")
+        btn_verify = QtWidgets.QPushButton(f"Verify ({duration:g}s)")
         ctr.addWidget(btn_verify)
 
         btn_apply = QtWidgets.QPushButton("Apply sync")
@@ -294,6 +300,7 @@ class SyncWindow(QtWidgets.QMainWindow):
         self.btn_stop.clicked.connect(self.stop_play)
 
         self.update_labels()
+        self._update_xcorr_label()
 
     def _set_lag(self, lag_sec: float, source: str = ""):
         if self._updating:
@@ -314,9 +321,23 @@ class SyncWindow(QtWidgets.QMainWindow):
         # pyqtgraph setPos shifts items; we recreate x
         # Instead shift data: plot t_b + lag
         self.curve_b.setData(self.t_b + shift, self.b_plot)
+        self._update_xcorr_label()
         self.update_labels()
         self._updating = False
 
+    def _update_xcorr_label(self):
+        N = len(self.corr)
+        idx = N // 2 + self.lag_samples
+        if 0 <= idx < N:
+            val = np.abs(self.corr[idx])
+            peak_val = np.abs(self.peak)
+            pct = (val / peak_val * 100) if peak_val > 0 else 0
+            self.xcorr_val_label.setText(
+                f"Xcorr at lag: {val:.6f}  (peak: {peak_val:.6f}  = {pct:.1f}%)"
+            )
+        else:
+            self.xcorr_val_label.setText("Xcorr at lag: (out of range)")
+
     def update_labels(self):
         lag_ms = self.lag_sec * 1000
         stem = os.path.splitext(os.path.basename(self.video_a))[0]
@@ -498,7 +519,7 @@ def main():
     args = ap.parse_args()
 
     cfg = load_config(args.config)
-    cfg_a, cfg_b, sr, _, _, volume = find_wavs_from_config(cfg)
+    cfg_a, cfg_b, sr, _, duration, volume = find_wavs_from_config(cfg)
     a_path = args.a or cfg_a
     b_path = args.b or cfg_b
     method = args.method or cfg.get("sync", {}).get("method", "phat")
@@ -546,7 +567,8 @@ def main():
     app.setPalette(dark)
     pg.setConfigOptions(antialias=True, background="#1e1e1e", foreground="#ddd")
     w = SyncWindow(a_path, b_path, sr=sr, method=method, device=device,
-                   video_a=video_a, video_b=video_b, out_dir=out_dir, volume=volume)
+                   video_a=video_a, video_b=video_b, out_dir=out_dir, volume=volume,
+                   duration=duration)
     w.show()
     sys.exit(app.exec())