ltx: vae: Move decoder output buffer allocation back to forward.

So none can mean none.

comfy/ldm/lightricks/vae/causal_video_autoencoder.py

@@ -640,13 +640,6 @@ class Decoder(nn.Module):
             )
             timestep_shift_scale = ada_values.unbind(dim=1)
 
-        #The meaning of output_buffer == None changes.
-        #forward now needs to do this for the non start-resume case.
-        if output_buffer is None:
-            output_buffer = torch.empty(
-                self.decode_output_shape(sample.shape),
-                dtype=sample.dtype, device=comfy.model_management.intermediate_device(),
-            )
         output_offset = [0]
 
         max_chunk_size = get_max_chunk_size(sample.device)
@@ -673,9 +666,19 @@ class Decoder(nn.Module):
         #we will design the protocol for signalling end to the caller later.
         raise NotImplementedError("Decoder.forward_resume is not implemented yet")
 
-    def forward(self, *args, **kwargs):
+    def forward(
+        self,
+        sample: torch.FloatTensor,
+        timestep: Optional[torch.Tensor] = None,
+        output_buffer: Optional[torch.Tensor] = None,
+    ):
+        if output_buffer is None:
+            output_buffer = torch.empty(
+                self.decode_output_shape(sample.shape),
+                dtype=sample.dtype, device=comfy.model_management.intermediate_device(),
+            )
         try:
-            return self.forward_orig(*args, **kwargs)
+            return self.forward_orig(sample, timestep=timestep, output_buffer=output_buffer)
         finally:
             for _, module in self.named_modules():
                 #ComfyUI doesn't thread this kind of stuff today, but just incase