refactor(video): 重构视频裁切功能实现

- 将 crop_size 字段替换为 crop_scale 浮点数字段，支持缩放倍率控制
- 将 face_pos 字段重命名为 crop_pos，统一裁切位置控制
- 移除 zoom_cut 和 crop_size 字段，简化裁切参数
- 新增 _build_crop_filter 静态方法，统一构建裁切滤镜逻辑
- 优化裁切算法，支持按目标比例和倍率进行精确裁切
- 统一处理图像和视频的裁切逻辑，消除代码重复
- 添加 cropScale 参数的安全解析，防止非法数值导致错误
- 改进裁切位置解析，支持浮点数坐标并添加异常处理

handlers/render_video.py

@@ -325,6 +325,43 @@ class RenderSegmentTsHandler(BaseHandler):
         finally:
             self.cleanup_work_dir(work_dir)
 
+    @staticmethod
+    def _build_crop_filter(
+        render_spec: 'RenderSpec',
+        width: int,
+        height: int,
+        task_id: str = ''
+    ) -> Optional[str]:
+        """
+        构建裁切滤镜
+
+        crop_enable 时：以目标比例为基准，按 crop_scale 倍率裁切，crop_pos 控制位置（默认居中）。
+
+        Returns:
+            crop 滤镜字符串，无需裁切时返回 None
+        """
+        if render_spec.crop_enable:
+            scale = render_spec.crop_scale
+            target_ratio = width / height
+
+            # 解析裁切位置，默认居中
+            fx, fy = 0.5, 0.5
+            if render_spec.crop_pos:
+                try:
+                    fx, fy = map(float, render_spec.crop_pos.split(','))
+                except ValueError:
+                    logger.warning(f"[task:{task_id}] Invalid crop position: {render_spec.crop_pos}, using center")
+                    fx, fy = 0.5, 0.5
+
+            # 基准：源中最大的目标比例矩形，再除以倍率
+            return (
+                f"crop='min(iw,ih*{target_ratio})/{scale}':'min(ih,iw/{target_ratio})/{scale}':"
+                f"'(iw-min(iw,ih*{target_ratio})/{scale})*{fx}':"
+                f"'(ih-min(ih,iw/{target_ratio})/{scale})*{fy}'"
+            )
+
+        return None
+
     def _convert_image_to_video(
         self,
         image_file: str,
@@ -373,23 +410,10 @@ class RenderSegmentTsHandler(BaseHandler):
         # 构建滤镜：缩放填充到目标尺寸
         filters = []
 
-        # 裁切处理（与视频相同逻辑）
-        if render_spec.crop_enable and render_spec.face_pos:
-            try:
-                fx, fy = map(float, render_spec.face_pos.split(','))
-                target_ratio = width / height
-                filters.append(
-                    f"crop='min(iw,ih*{target_ratio})':'min(ih,iw/{target_ratio})':"
-                    f"'(iw-min(iw,ih*{target_ratio}))*{fx}':"
-                    f"'(ih-min(ih,iw/{target_ratio}))*{fy}'"
-                )
-            except (ValueError, ZeroDivisionError):
-                logger.warning(f"[task:{task_id}] Invalid face position: {render_spec.face_pos}")
-        elif render_spec.zoom_cut:
-            target_ratio = width / height
-            filters.append(
-                f"crop='min(iw,ih*{target_ratio})':'min(ih,iw/{target_ratio})'"
-            )
+        # 裁切处理
+        crop_filter = self._build_crop_filter(render_spec, width, height, task_id)
+        if crop_filter:
+            filters.append(crop_filter)
 
         # 缩放填充
         filters.append(
@@ -711,26 +735,9 @@ class RenderSegmentTsHandler(BaseHandler):
             filters.append(f"lut3d='{lut_path}'")
 
         # 3. 裁切处理
-        if render_spec.crop_enable and render_spec.face_pos:
-            # 根据人脸位置进行智能裁切
-            try:
-                fx, fy = map(float, render_spec.face_pos.split(','))
-                # 计算裁切区域（保持输出比例）
-                target_ratio = width / height
-                # 假设裁切到目标比例
-                filters.append(
-                    f"crop='min(iw,ih*{target_ratio})':'min(ih,iw/{target_ratio})':"
-                    f"'(iw-min(iw,ih*{target_ratio}))*{fx}':"
-                    f"'(ih-min(ih,iw/{target_ratio}))*{fy}'"
-                )
-            except (ValueError, ZeroDivisionError):
-                logger.warning(f"Invalid face position: {render_spec.face_pos}")
-        elif render_spec.zoom_cut:
-            # 中心缩放裁切
-            target_ratio = width / height
-            filters.append(
-                f"crop='min(iw,ih*{target_ratio})':'min(ih,iw/{target_ratio})'"
-            )
+        crop_filter = self._build_crop_filter(render_spec, width, height)
+        if crop_filter:
+            filters.append(crop_filter)
 
         # 4. 缩放和填充
         scale_filter = (