[feature] : add cache-dit for stable-audio-open-1.0 (#1341)

Signed-off-by: akshatvishu <akshatnayak197@gmail.com>

vllm_omni/diffusion/cache/cache_dit_backend.py

@@ -464,6 +464,77 @@ def enable_cache_for_flux2_klein(pipeline: Any, cache_config: Any) -> Callable[[
     return refresh_cache_context
 
 
+def enable_cache_for_stable_audio_open(pipeline: Any, cache_config: Any) -> Callable[[int], None]:
+    """Enable cache-dit for Stable Audio Open pipeline.
+
+    Args:
+        pipeline: The StableAudioPipeline instance.
+        cache_config: DiffusionCacheConfig instance with cache configuration.
+
+    Returns:
+        A refresh function that can be called to update cache context with new num_inference_steps.
+    """
+    db_cache_config = _build_db_cache_config(cache_config)
+
+    calibrator_config = None
+    if cache_config.enable_taylorseer:
+        taylorseer_order = cache_config.taylorseer_order
+        calibrator_config = TaylorSeerCalibratorConfig(taylorseer_order=taylorseer_order)
+        logger.info(f"TaylorSeer enabled with order={taylorseer_order}")
+
+    # StableAudio is officially registered in CacheDiT as Pattern_3:
+    # https://github.com/vipshop/cache-dit/blob/69e82bd1/src/cache_dit/caching/block_adapters/__init__.py#L562
+    #
+    # Pattern_3 is required because StableAudioDiT uses cross-attention
+    # with static encoder_hidden_states that do not change inside the
+    # transformer block loop.
+    cache_dit.enable_cache(
+        BlockAdapter(
+            transformer=pipeline.transformer,
+            blocks=pipeline.transformer.transformer_blocks,
+            forward_pattern=ForwardPattern.Pattern_3,
+            params_modifiers=[
+                ParamsModifier(
+                    cache_config=db_cache_config,
+                    calibrator_config=calibrator_config,
+                )
+            ],
+        ),
+        cache_config=db_cache_config,
+    )
+
+    def refresh_cache_context(pipeline: Any, num_inference_steps: int, verbose: bool = True) -> None:
+        """Refresh cache context for the transformer with new num_inference_steps.
+
+        Args:
+            pipeline: The StableAudioPipeline instance.
+            num_inference_steps: New number of inference steps.
+            verbose: Whether to log refresh operations.
+        """
+        # Bypass SCM for step counts that don't support predefined masks (e.g., vLLM's 1-step dummy run)
+        scm_supported_steps = num_inference_steps >= 8 or num_inference_steps in (4, 6)
+
+        if cache_config.scm_steps_mask_policy is None or not scm_supported_steps:
+            cache_dit.refresh_context(pipeline.transformer, num_inference_steps=num_inference_steps, verbose=verbose)
+        else:
+            updated_scm_config = DBCacheConfig().reset(
+                num_inference_steps=num_inference_steps,
+                steps_computation_mask=cache_dit.steps_mask(
+                    mask_policy=cache_config.scm_steps_mask_policy,
+                    total_steps=num_inference_steps,
+                ),
+                steps_computation_policy=cache_config.scm_steps_policy,
+            )
+
+            cache_dit.refresh_context(
+                pipeline.transformer,
+                cache_config=updated_scm_config,
+                verbose=verbose,
+            )
+
+    return refresh_cache_context
+
+
 def enable_cache_for_sd3(pipeline: Any, cache_config: Any) -> Callable[[int], None]:
     """Enable cache-dit for StableDiffusion3Pipeline.
 
@@ -1212,6 +1283,7 @@ CUSTOM_DIT_ENABLERS.update(
         "Flux2KleinPipeline": enable_cache_for_flux2_klein,
         "LongCatImagePipeline": enable_cache_for_longcat_image,
         "LongCatImageEditPipeline": enable_cache_for_longcat_image,
+        "StableAudioPipeline": enable_cache_for_stable_audio_open,
         "StableDiffusion3Pipeline": enable_cache_for_sd3,
         "LTX2Pipeline": enable_cache_for_ltx2,
         "LTX2ImageToVideoPipeline": enable_cache_for_ltx2,

vllm_omni/diffusion/models/stable_audio/stable_audio_transformer.py

@@ -375,6 +375,8 @@ class StableAudioDiTModel(nn.Module):
     - Output: [B, out_channels, L]
     """
 
+    _repeated_blocks = ["StableAudioDiTBlock"]
+
     def __init__(
         self,
         od_config: OmniDiffusionConfig | None = None,