[Diffusion] Fix FastWan2.1 default 480p resolution (#28733)

python/sglang/multimodal_gen/configs/sample/wan.py

@@ -171,7 +171,7 @@ class FastWanT2V480PConfig(WanT2V_1_3B_SamplingParams):
     # dmd_denoising_steps: list[int] | None = field(default_factory=lambda: [1000, 757, 522])
     num_inference_steps: int = 3
     num_frames: int = 61
-    height: int = 448
+    height: int = 480
     width: int = 832
     fps: int = 16
 

python/sglang/multimodal_gen/test/unit/test_sampling_params.py

@@ -24,6 +24,7 @@ from sglang.multimodal_gen.configs.sample.sampling_params import (
 )
 from sglang.multimodal_gen.configs.sample.teacache import TeaCacheParams
 from sglang.multimodal_gen.configs.sample.wan import (
+    FastWanT2V480PConfig,
     WanI2V_14B_480P_SamplingParam,
     WanI2V_14B_720P_SamplingParam,
     WanT2V_1_3B_SamplingParams,
@@ -102,6 +103,12 @@ class TestSamplingParamsSubclass(unittest.TestCase):
         with self.assertRaises(AssertionError):
             DiffusersGenericSamplingParams(num_frames=0)
 
+    def test_fastwan_480p_default_resolution_is_supported(self):
+        params = FastWanT2V480PConfig()
+
+        self.assertEqual((params.width, params.height), (832, 480))
+        self.assertIn((params.width, params.height), params.supported_resolutions)
+
     def test_output_file_name_supports_callable_teacache_params(self):
         def coefficients_callback(_: TeaCacheParams) -> list[float]:
             return [1.0, 2.0, 3.0, 4.0, 5.0]