fix(entity): 修复中心裁剪计算逻辑并优化 JSON 解析

- 在解析 posJson 时添加异常处理，避免无效 JSON 导致程序崩溃
- 修复中心裁剪计算逻辑中的取整问题，确保裁剪位置准确

entity/ffmpeg.py

@@ -190,7 +190,10 @@ class FfmpegTask(object):
                     input_args.append(input_file.get_output_file())
             if self.center_cut == 1:
                 pos_json_str = self.ext_data.get('posJson', '{}')
+                try:
                     pos_json = json.loads(pos_json_str)
+                except Exception as e:
+                    pos_json = {}
                 _v_w = pos_json.get('imgWidth', 1)
                 _f_x = pos_json.get('ltX', 0)
                 _f_x2 = pos_json.get('rbX', 0)
@@ -212,15 +215,18 @@ class FfmpegTask(object):
                     _iw, _ih, _ = probe_video_info(_input)
                     _w, _h = self.resolution.split('x', 1)
                     pos_json_str = self.ext_data.get('posJson', '{}')
+                    try:
                         pos_json = json.loads(pos_json_str)
+                    except Exception as e:
+                        pos_json = {}
                     _v_w = pos_json.get('imgWidth', 1)
                     _v_h = pos_json.get('imgHeight', 1)
                     _f_x = pos_json.get('ltX', 0)
                     _f_x2 = pos_json.get('rbX', 0)
                     _f_y = pos_json.get('ltY', 0)
                     _f_y2 = pos_json.get('rbY', 0)
-                    _x = min(max(0, (_f_x + _f_x2) / 2 - int(_w) / 2), _iw - int(_w))
-                    _y = min(max(0, (_f_y + _f_y2) / 2 - int(_h) / 2), _ih - int(_h))
+                    _x = min(max(0, int((_f_x + _f_x2) / 2 - int(_w) / 2)), _iw - int(_w))
+                    _y = min(max(0, int((_f_y + _f_y2) / 2 - int(_h) / 2)), _ih - int(_h))
                     filter_args.append(f"{video_output_str}crop=x={_x}:y={_y}:w={_w}:h={_h}[vz_cut{effect_index}]")
                     video_output_str = f"[vz_cut{effect_index}]"
                     effect_index += 1