[Feature] feat: add video frame interpolation postprocess (#2555)

Signed-off-by: David Chen <530634352@qq.com>

vllm_omni/diffusion/diffusion_engine.py

@@ -3,6 +3,7 @@
 
 from __future__ import annotations
 
+import inspect
 import queue
 import threading
 import time
@@ -78,6 +79,12 @@ class DiffusionEngine:
 
         self.post_process_func = get_diffusion_post_process_func(od_config)
         self.pre_process_func = get_diffusion_pre_process_func(od_config)
+        # Cache whether the model-specific postprocess accepts request-level
+        # sampling params so step() can support both legacy and extended hooks.
+        self._post_process_accepts_sampling_params = bool(
+            self.post_process_func is not None
+            and "sampling_params" in inspect.signature(self.post_process_func).parameters
+        )
 
         executor_class = DiffusionExecutor.get_class(od_config)
         self.executor = executor_class(od_config)
@@ -143,12 +150,22 @@ class DiffusionEngine:
             output_data = output_data.cpu()
 
         postprocess_start_time = time.perf_counter()
-        outputs = self.post_process_func(output_data) if self.post_process_func is not None else output_data
+        if self.post_process_func is not None:
+            # Some video pipelines need request-level controls during
+            # postprocess (for example worker-side frame interpolation).
+            if self._post_process_accepts_sampling_params:
+                outputs = self.post_process_func(output_data, sampling_params=request.sampling_params)
+            else:
+                outputs = self.post_process_func(output_data)
+        else:
+            outputs = output_data
         audio_payload = None
+        custom_output = output.custom_output or {}
         model_audio_sample_rate = None
         model_fps = None
         if isinstance(outputs, dict):
             audio_payload = outputs.get("audio")
+            custom_output.update(outputs.get("custom_output") or {})
             model_audio_sample_rate = outputs.get("audio_sample_rate")
             model_fps = outputs.get("fps")
             outputs = outputs.get("video", outputs)
@@ -225,7 +242,7 @@ class DiffusionEngine:
                         trajectory_timesteps=output.trajectory_timesteps,
                         trajectory_log_probs=output.trajectory_log_probs,
                         trajectory_decoded=output.trajectory_decoded,
-                        custom_output=output.custom_output or {},
+                        custom_output=custom_output,
                         multimodal_output=mm_output,
                         stage_durations=output.stage_durations,
                         peak_memory_mb=output.peak_memory_mb,
@@ -295,7 +312,7 @@ class DiffusionEngine:
                             trajectory_timesteps=output.trajectory_timesteps,
                             trajectory_log_probs=output.trajectory_log_probs,
                             trajectory_decoded=output.trajectory_decoded,
-                            custom_output=output.custom_output or {},
+                            custom_output=custom_output,
                             multimodal_output=mm_output,
                             stage_durations=output.stage_durations,
                             peak_memory_mb=output.peak_memory_mb,