feat: add adjustable playback duration for A/B samples

sync_audio_test.py

@@ -249,10 +249,21 @@ class SyncWindow(QtWidgets.QMainWindow):
         self.vol_label = QtWidgets.QLabel("70%")
         ctr2.addWidget(self.vol_label)
 
-        self.btn_play_a = QtWidgets.QPushButton("Play A (2s)")
+        self.btn_play_a = QtWidgets.QPushButton("Play A")
-        self.btn_play_b = QtWidgets.QPushButton("Play B+lag (2s)")
+        self.btn_play_b = QtWidgets.QPushButton("Play B+lag")
         self.btn_play_mix = QtWidgets.QPushButton("Play Mix")
         self.btn_stop = QtWidgets.QPushButton("Stop")
+
+        ctr2.addWidget(QtWidgets.QLabel("Duration:"))
+        self.play_dur = QtWidgets.QDoubleSpinBox()
+        self.play_dur.setRange(0.1, 30.0)
+        self.play_dur.setDecimals(1)
+        self.play_dur.setSingleStep(0.5)
+        self.play_dur.setValue(2.0)
+        self.play_dur.setSuffix("s")
+        self.play_dur.setMaximumWidth(80)
+        ctr2.addWidget(self.play_dur)
+
         for b in [self.btn_play_a, self.btn_play_b, self.btn_play_mix, self.btn_stop]:
             ctr2.addWidget(b)
         if not HAS_SD:
@@ -398,9 +409,8 @@ class SyncWindow(QtWidgets.QMainWindow):
             return
         vol = self.vol.value()/100.0
         sr = self.sr
-        # play 2 seconds from 10s mark to hear sync
+        dur_samp = int(self.play_dur.value() * sr)
         start_samp = int(10 * sr)
-        dur_samp = int(2 * sr)
         if start_samp + dur_samp > len(self.a_orig):
             start_samp = 0
         a_seg = self.a_orig[start_samp:start_samp+dur_samp] * vol