Optimize positional embedding handling in TransformerArgsPreprocessor and improve RoPE frequency computation in _precompute_freqs_cis_double_precision for enhanced performance and precision.

mlx_video/models/ltx/transformer.py

@@ -12,12 +12,14 @@ from mlx_video.utils import rms_norm
 
 @dataclass(frozen=True)
 class Modality:
-    latent: mx.array  
-    timesteps: mx.array  
-    positions: mx.array  
-    context: mx.array  
+    latent: mx.array
+    timesteps: mx.array
+    positions: mx.array
+    context: mx.array
     enabled: bool = True
     context_mask: Optional[mx.array] = None
+    # Optional precomputed positional embeddings (RoPE) to avoid recomputation
+    positional_embeddings: Optional[Tuple[mx.array, mx.array]] = None
 
 
 @dataclass(frozen=True)