fix(P0): 修复直通模式调速失效+音画不同步

- stream_copy没检查调速/倒放，有调速时错误走流拷贝导致调速失效
- 直通模式视频setpts调速了但音频没atempo调速，音画不同步
- 修复多个音频滤镜用独立-af参数互相覆盖的问题

apps/worker/video_processing/unified_render_service.py

@@ -801,6 +801,16 @@ class UnifiedRenderService:
         if ass_path is not None:
             return False, "有字幕叠加"
 
+        # 有调速 → 需要重编码 → 不能 copy
+        speed = UnifiedRenderService._clip_speed(clip)
+        if abs(speed - 1.0) >= 1e-6:
+            return False, f"有调速: speed={speed:.2f}x"
+
+        # 有倒放 → 需要重编码 → 不能 copy
+        reverse_config = ReverseConfig.from_dict(clip.config.get("reverse"))
+        if reverse_config.enabled and (reverse_config.reverse_video or reverse_config.reverse_audio):
+            return False, "有倒放效果"
+
         # 探测输入视频参数
         info = probe_video_info(str(clip.local_path))
 
@@ -1068,8 +1078,9 @@ class UnifiedRenderService:
         # background 以外的视频素材，默认带音频
         has_audio = role != "background"
         if has_audio:
-            # 检查是否需要音频降噪
             af_parts: list[str] = []
+
+            # 音频降噪
             try:
                 from video_processing.noise_reduction_engine import NoiseReductionConfig, NoiseReductionEngine
 
@@ -1083,17 +1094,29 @@ class UnifiedRenderService:
             except Exception as e:
                 logger.warning("[unified-render] 直通模式音频降噪应用失败，跳过: %s", e)
 
-            if af_parts:
-                command.extend(["-af", ",".join(af_parts)])
+            # 音频调速（与视频setpts对应，保持音画同步）
+            speed = UnifiedRenderService._clip_speed(clip)
+            if abs(speed - 1.0) >= 1e-6:
+                try:
+                    from video_processing.speed_engine import SpeedConfig, SpeedEngine
 
-            command.extend(["-c:a", "aac", "-b:a", "128k"])
+                    speed_cfg = SpeedConfig(speed=speed)
+                    speed_engine = SpeedEngine()
+                    af_parts.append(speed_engine.build_audio_filter(speed_cfg))
+                except Exception as e:
+                    logger.warning("[unified-render] 直通模式音频调速应用失败，跳过: %s", e)
 
             # 音频倒放
             reverse_config = ReverseConfig.from_dict(clip.config.get("reverse"))
             if reverse_config.enabled and reverse_config.reverse_audio:
                 af_filter = ReverseEngine.build_audio_filter(reverse_config, duration=effective_duration)
                 if af_filter:
-                    command.extend(["-af", af_filter])
+                    af_parts.append(af_filter)
+
+            if af_parts:
+                command.extend(["-af", ",".join(af_parts)])
+
+            command.extend(["-c:a", "aac", "-b:a", "128k"])
 
         # 统一截断时长（同时作用于视频和音频）
         if final_duration > 0: