feat: play/stop audition of the current audio region

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

main.py

@@ -4533,6 +4533,12 @@ class MainWindow(QMainWindow):
         self._btn_wave_refresh.setToolTip(
             "Decode the current audio area and draw its waveform")
         self._btn_wave_refresh.clicked.connect(self._on_wave_refresh)
+        self._btn_audio_play = QPushButton("▶ Play")
+        self._btn_audio_play.setCheckable(True)
+        self._btn_audio_play.setToolTip(
+            "Audition the current audio area (with the edits applied)")
+        self._btn_audio_play.toggled.connect(self._on_audio_audition)
+        self._audition_proc = None   # QProcess while auditioning, else None
         self._transport_row = transport_row
 
         # Row 1b — subcategory (subprofile) export buttons live on their own
@@ -4838,6 +4844,7 @@ class MainWindow(QMainWindow):
         # Row 4 — read-only waveform strip for the current audio area.
         g.addWidget(self._wave, 4, 0, 1, 4)
         g.addWidget(self._btn_wave_refresh, 5, 0, 1, 2)
+        g.addWidget(self._btn_audio_play, 5, 2, 1, 2)
         g.addWidget(self._btn_extract_audio, 6, 0, 1, 4)
         g.setColumnStretch(4, 1)   # spare gutter column clusters label/field pairs to the left
         g.setRowStretch(7, 1)      # anchor content to the top
@@ -6523,6 +6530,84 @@ class MainWindow(QMainWindow):
         elif preview < dur:
             self._show_status(f"Waveform shows first {preview:.0f}s of {dur:.0f}s", 4000)
 
+    def _current_edit_filters(self) -> list[str]:
+        """ffmpeg -af chain for the current edit controls (shared by extract +
+        audition so they never drift)."""
+        return audio_edit_filters(
+            duration=self._spn_audio_len.value(),
+            fade_in=self._spn_fade_in.value(),
+            fade_out=self._spn_fade_out.value(),
+            normalize=self._chk_normalize.isChecked(),
+            gain_db=self._spn_gain.value())
+
+    def _on_audio_audition(self, playing: bool) -> None:
+        """Toggle audition of the current region (with edits) via ffplay."""
+        if not playing:
+            self._stop_audition()
+            return
+        if not self._file_path:
+            self._btn_audio_play.setChecked(False)
+            return
+        import tempfile
+        from PyQt6.QtCore import QProcess
+        start = self._cursor
+        dur = self._spn_audio_len.value()
+        edit_filters = self._current_edit_filters()
+        tmp = os.path.join(tempfile.gettempdir(), "8cut_audition.wav")
+        cmd = build_audio_clip_command(self._file_path, start, dur, tmp,
+                                       filters=edit_filters or None)
+        QApplication.setOverrideCursor(Qt.CursorShape.WaitCursor)
+        self._show_status("Auditioning…")
+        try:
+            proc = subprocess.run(cmd, capture_output=True, timeout=120)
+        except Exception:
+            proc = None
+        finally:
+            QApplication.restoreOverrideCursor()
+        if proc is None or proc.returncode != 0 or not os.path.exists(tmp):
+            self._btn_audio_play.setChecked(False)
+            self._show_status("Audition render failed", 3000)
+            return
+        self._audition_proc = QProcess(self)
+        self._audition_proc.finished.connect(self._on_audition_finished)
+        self._audition_proc.errorOccurred.connect(self._on_audition_error)
+        self._audition_proc.start(
+            _bin("ffplay"), ["-autoexit", "-nodisp", "-loglevel", "error", tmp])
+        self._btn_audio_play.setText("■ Stop")
+
+    def _on_audition_error(self, _err) -> None:
+        self._show_status("Audio playback unavailable (ffplay not found)", 4000)
+        self._teardown_audition()
+
+    def _on_audition_finished(self, *_a) -> None:
+        self._teardown_audition()
+
+    def _teardown_audition(self) -> None:
+        proc = self._audition_proc
+        self._audition_proc = None
+        if proc is not None:
+            proc.deleteLater()
+        self._btn_audio_play.setText("▶ Play")
+        # Snap the toggle back without re-entering start logic.
+        if self._btn_audio_play.isChecked():
+            self._btn_audio_play.blockSignals(True)
+            self._btn_audio_play.setChecked(False)
+            self._btn_audio_play.blockSignals(False)
+
+    def _stop_audition(self) -> None:
+        proc = self._audition_proc
+        self._audition_proc = None
+        if proc is not None:
+            try:
+                proc.finished.disconnect()
+                proc.errorOccurred.disconnect()
+            except Exception:
+                pass
+            proc.kill()
+            proc.waitForFinished(100)
+            proc.deleteLater()
+        self._btn_audio_play.setText("▶ Play")
+
     def _on_extract_audio(self) -> None:
         """Extract an exact-length audio slice starting at the playhead and
         prompt for where to save it (format follows the chosen extension)."""
@@ -6556,12 +6641,7 @@ class MainWindow(QMainWindow):
         if not os.path.splitext(path)[1]:
             path += ext
         os.makedirs(os.path.dirname(path) or ".", exist_ok=True)
-        edit_filters = audio_edit_filters(
-            duration=dur,
-            fade_in=self._spn_fade_in.value(),
-            fade_out=self._spn_fade_out.value(),
-            normalize=self._chk_normalize.isChecked(),
-            gain_db=self._spn_gain.value())
+        edit_filters = self._current_edit_filters()
         cmd = build_audio_clip_command(self._file_path, start, dur, path,
                                        filters=edit_filters or None)
         self._btn_extract_audio.setEnabled(False)