Fix rotary positional embedding dimension mismatch in Wan and SkyReels V2 transformers (#12594)

* Fix rotary positional embedding dimension mismatch in Wan and SkyReels V2 transformers

- Store t_dim, h_dim, w_dim as instance variables in WanRotaryPosEmbed and SkyReelsV2RotaryPosEmbed __init__
- Use stored dimensions in forward() instead of recalculating with different formula
- Fixes inconsistency between init (using // 6) and forward (using // 3)
- Ensures split_sizes matches the dimensions used to create rotary embeddings

* quality fix

---------
Co-authored-by: Charchit Sharma <charchitsharma@A-267.local>

src/diffusers/models/transformers/transformer_skyreels_v2.py

@@ -389,6 +389,10 @@ class SkyReelsV2RotaryPosEmbed(nn.Module):
         t_dim = attention_head_dim - h_dim - w_dim
         freqs_dtype = torch.float32 if torch.backends.mps.is_available() else torch.float64
 
+        self.t_dim = t_dim
+        self.h_dim = h_dim
+        self.w_dim = w_dim
+
         freqs_cos = []
         freqs_sin = []
 
@@ -412,11 +416,7 @@ class SkyReelsV2RotaryPosEmbed(nn.Module):
         p_t, p_h, p_w = self.patch_size
         ppf, pph, ppw = num_frames // p_t, height // p_h, width // p_w
 
-        split_sizes = [
-            self.attention_head_dim - 2 * (self.attention_head_dim // 3),
-            self.attention_head_dim // 3,
-            self.attention_head_dim // 3,
-        ]
+        split_sizes = [self.t_dim, self.h_dim, self.w_dim]
 
         freqs_cos = self.freqs_cos.split(split_sizes, dim=1)
         freqs_sin = self.freqs_sin.split(split_sizes, dim=1)

src/diffusers/models/transformers/transformer_wan.py

@@ -362,6 +362,11 @@ class WanRotaryPosEmbed(nn.Module):
 
         h_dim = w_dim = 2 * (attention_head_dim // 6)
         t_dim = attention_head_dim - h_dim - w_dim
+
+        self.t_dim = t_dim
+        self.h_dim = h_dim
+        self.w_dim = w_dim
+
         freqs_dtype = torch.float32 if torch.backends.mps.is_available() else torch.float64
 
         freqs_cos = []
@@ -387,11 +392,7 @@ class WanRotaryPosEmbed(nn.Module):
         p_t, p_h, p_w = self.patch_size
         ppf, pph, ppw = num_frames // p_t, height // p_h, width // p_w
 
-        split_sizes = [
-            self.attention_head_dim - 2 * (self.attention_head_dim // 3),
-            self.attention_head_dim // 3,
-            self.attention_head_dim // 3,
-        ]
+        split_sizes = [self.t_dim, self.h_dim, self.w_dim]
 
         freqs_cos = self.freqs_cos.split(split_sizes, dim=1)
         freqs_sin = self.freqs_sin.split(split_sizes, dim=1)