fix: export Demucs stems through ffmpeg

experiments/bs-roformer-vocal-separation/app.py

@@ -60,11 +60,10 @@ def _run_separator(input_path: Path, output_dir: Path, mode: dict) -> None:
         "--output_dir", str(output_dir),
         "--output_format", "FLAC",
         "--sample_rate", "44100",
-        "--use_soundfile",
         "--use_autocast",
     ]
     if mode["engine"] == "mdxc":
-        args.extend(["--mdxc_segment_size", "256", "--mdxc_overlap", "8", "--mdxc_batch_size", "1"])
+        args.extend(["--use_soundfile", "--mdxc_segment_size", "256", "--mdxc_overlap", "8", "--mdxc_batch_size", "1"])
     else:
         args.extend(["--demucs_segment_size", "40", "--demucs_shifts", "2", "--demucs_overlap", "0.25"])
     completed = subprocess.run(args, capture_output=True, text=True, timeout=7200)