perf(#1280): 预览视频生成加速 — ultrafast编码+并行下载+跳过非必要步骤 (#1284)

apps/worker/video_processing/unified_render_service.py

@@ -151,6 +151,7 @@ class UnifiedRenderService:
         asr_service: Any = None,  # ASRService 实例，用于自动生成字幕
         bgm_path: str | None = None,  # BGM 本地文件路径
         voiceover_audio_path: str | None = None,  # 配音素材库音频本地路径
+        is_preview: bool = False,  # 预览模式：ultrafast 编码 + 跳过非必要步骤
     ):
         self.plan = plan
         self.clips = clips
@@ -163,6 +164,7 @@ class UnifiedRenderService:
         self.asr_service = asr_service
         self.bgm_path = bgm_path
         self.voiceover_audio_path = voiceover_audio_path
+        self.is_preview = is_preview
         self._transition_engine = TransitionEngine(default_duration=transition_duration)
         self._speed_engine = SpeedEngine()
         self._asr_timeline_cache: Any = None  # ASR 字幕结果缓存，避免重复调用
@@ -1228,9 +1230,9 @@ class UnifiedRenderService:
             "-c:v",
             "libx264",
             "-crf",
-            "23",
+            "28" if self.is_preview else "23",
             "-preset",
-            "medium",
+            "ultrafast" if self.is_preview else "medium",
             "-pix_fmt",
             "yuv420p",
             "-movflags",
@@ -1742,9 +1744,9 @@ class UnifiedRenderService:
             "-c:v",
             "libx264",
             "-crf",
-            "23",
+            "28" if self.is_preview else "23",
             "-preset",
-            "medium",
+            "ultrafast" if self.is_preview else "medium",
             "-pix_fmt",
             "yuv420p",
             "-movflags",
@@ -1753,10 +1755,11 @@ class UnifiedRenderService:
         ]
 
         logger.info(
-            "执行渲染: plan_id=%s inputs=%d output=%s",
+            "执行渲染: plan_id=%s inputs=%d output=%s preview=%s",
             self.plan.id,
             input_args.count("-i"),
             output_path,
+            self.is_preview,
         )
         try:
             run_ffmpeg(command)