Update app.py

app.py

@@ -62,14 +62,20 @@ def fast_align(source, target_len):
 
 def separate_stems(input_file, job_id):
     out_dir = f"sep_{job_id}"
-    subprocess.run([
+
+    cmd = [
         "demucs",
         "-n", "mdx_q",
         "--two-stems=drums",
-        "--device", DEVICE,
         "--out", out_dir,
         input_file
-    ], check=True)
+    ]
+
+    if DEVICE == "cuda":
+        cmd.insert(4, "--device")
+        cmd.insert(5, "cuda")
+
+    subprocess.run(cmd, check=True)
 
     base = os.path.splitext(os.path.basename(input_file))[0]
     stem_dir = os.path.join(out_dir, "mdx_q", base)
@@ -187,6 +193,7 @@ def fuse_api():
 
     except Exception as e:
         return jsonify({"error": str(e)}), 500
+
     finally:
         for f in temp_files:
             if os.path.exists(f):
@@ -194,5 +201,7 @@ def fuse_api():
         for d in cleanup_dirs:
             if os.path.exists(d):
                 shutil.rmtree(d, ignore_errors=True)
+
+
 if __name__ == "__main__":
     app.run(host='0.0.0.0', port=7860)