Update docs/source/en/optimization/attention_backends.md

Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>

docs/source/en/optimization/attention_backends.md

@@ -35,7 +35,7 @@ The [`~ModelMixin.set_attention_backend`] method iterates through all the module
 The example below demonstrates how to enable the `_flash_3_hub` implementation for FlashAttention-3 from the [`kernels`](https://github.com/huggingface/kernels) library, which allows you to instantly use optimized compute kernels from the Hub without requiring any setup.
 
 > [!NOTE]
-> FlashAttention-3 is not supported for non-Hopper architectures, in which case, use FlashAttention with `set_attention_backend("flash")`.
+> FlashAttention-3 requires Ampere GPUs at a minimum.
 
 ```py
 import torch

scripts/convert_sana_video_to_diffusers.py

@@ -12,6 +12,7 @@ from termcolor import colored
 from transformers import AutoModelForCausalLM, AutoTokenizer
 
 from diffusers import (
+    AutoencoderKLLTX2Video,
     AutoencoderKLWan,
     DPMSolverMultistepScheduler,
     FlowMatchEulerDiscreteScheduler,
@@ -24,7 +25,10 @@ from diffusers.utils.import_utils import is_accelerate_available
 
 CTX = init_empty_weights if is_accelerate_available else nullcontext
 
-ckpt_ids = ["Efficient-Large-Model/SANA-Video_2B_480p/checkpoints/SANA_Video_2B_480p.pth"]
+ckpt_ids = [
+    "Efficient-Large-Model/SANA-Video_2B_480p/checkpoints/SANA_Video_2B_480p.pth",
+    "Efficient-Large-Model/SANA-Video_2B_720p/checkpoints/SANA_Video_2B_720p_LTXVAE.pth",
+]
 # https://github.com/NVlabs/Sana/blob/main/inference_video_scripts/inference_sana_video.py
 
 
@@ -92,12 +96,22 @@ def main(args):
     if args.video_size == 480:
         sample_size = 30  # Wan-VAE: 8xp2 downsample factor
         patch_size = (1, 2, 2)
+        in_channels = 16
+        out_channels = 16
     elif args.video_size == 720:
-        sample_size = 22  # Wan-VAE: 32xp1 downsample factor
+        sample_size = 22  # DC-AE-V: 32xp1 downsample factor
         patch_size = (1, 1, 1)
+        in_channels = 32
+        out_channels = 32
     else:
         raise ValueError(f"Video size {args.video_size} is not supported.")
 
+    if args.vae_type == "ltx2":
+        sample_size = 22
+        patch_size = (1, 1, 1)
+        in_channels = 128
+        out_channels = 128
+
     for depth in range(layer_num):
         # Transformer blocks.
         converted_state_dict[f"transformer_blocks.{depth}.scale_shift_table"] = state_dict.pop(
@@ -182,8 +196,8 @@ def main(args):
     # Transformer
     with CTX():
         transformer_kwargs = {
-            "in_channels": 16,
-            "out_channels": 16,
+            "in_channels": in_channels,
+            "out_channels": out_channels,
             "num_attention_heads": 20,
             "attention_head_dim": 112,
             "num_layers": 20,
@@ -235,9 +249,12 @@ def main(args):
     else:
         print(colored(f"Saving the whole Pipeline containing {args.model_type}", "green", attrs=["bold"]))
         # VAE
-        vae = AutoencoderKLWan.from_pretrained(
-            "Wan-AI/Wan2.1-T2V-1.3B-Diffusers", subfolder="vae", torch_dtype=torch.float32
-        )
+        if args.vae_type == "ltx2":
+            vae_path = args.vae_path or "Lightricks/LTX-2"
+            vae = AutoencoderKLLTX2Video.from_pretrained(vae_path, subfolder="vae", torch_dtype=torch.float32)
+        else:
+            vae_path = args.vae_path or "Wan-AI/Wan2.1-T2V-1.3B-Diffusers"
+            vae = AutoencoderKLWan.from_pretrained(vae_path, subfolder="vae", torch_dtype=torch.float32)
 
         # Text Encoder
         text_encoder_model_path = "Efficient-Large-Model/gemma-2-2b-it"
@@ -314,7 +331,23 @@ if __name__ == "__main__":
         choices=["flow-dpm_solver", "flow-euler", "uni-pc"],
         help="Scheduler type to use.",
     )
-    parser.add_argument("--task", default="t2v", type=str, required=True, help="Task to convert, t2v or i2v.")
+    parser.add_argument(
+        "--vae_type",
+        default="wan",
+        type=str,
+        choices=["wan", "ltx2"],
+        help="VAE type to use for saving full pipeline (ltx2 uses patchify 1x1x1).",
+    )
+    parser.add_argument(
+        "--vae_path",
+        default=None,
+        type=str,
+        required=False,
+        help="Optional VAE path or repo id. If not set, a default is used per VAE type.",
+    )
+    parser.add_argument(
+        "--task", default="t2v", type=str, required=True, choices=["t2v", "i2v"], help="Task to convert, t2v or i2v."
+    )
     parser.add_argument("--dump_path", default=None, type=str, required=True, help="Path to the output pipeline.")
     parser.add_argument("--save_full_pipeline", action="store_true", help="save all the pipeline elements in one.")
     parser.add_argument("--dtype", default="fp32", type=str, choices=["fp32", "fp16", "bf16"], help="Weight dtype.")

src/diffusers/pipelines/sana_video/pipeline_sana_video.py

@@ -24,7 +24,7 @@ from transformers import Gemma2PreTrainedModel, GemmaTokenizer, GemmaTokenizerFa
 
 from ...callbacks import MultiPipelineCallbacks, PipelineCallback
 from ...loaders import SanaLoraLoaderMixin
-from ...models import AutoencoderDC, AutoencoderKLWan, SanaVideoTransformer3DModel
+from ...models import AutoencoderDC, AutoencoderKLLTX2Video, AutoencoderKLWan, SanaVideoTransformer3DModel
 from ...schedulers import DPMSolverMultistepScheduler
 from ...utils import (
     BACKENDS_MAPPING,
@@ -194,7 +194,7 @@ class SanaVideoPipeline(DiffusionPipeline, SanaLoraLoaderMixin):
             The tokenizer used to tokenize the prompt.
         text_encoder ([`Gemma2PreTrainedModel`]):
             Text encoder model to encode the input prompts.
-        vae ([`AutoencoderKLWan` or `AutoencoderDCAEV`]):
+        vae ([`AutoencoderKLWan`, `AutoencoderDC`, or `AutoencoderKLLTX2Video`]):
             Variational Auto-Encoder (VAE) Model to encode and decode videos to and from latent representations.
         transformer ([`SanaVideoTransformer3DModel`]):
             Conditional Transformer to denoise the input latents.
@@ -213,7 +213,7 @@ class SanaVideoPipeline(DiffusionPipeline, SanaLoraLoaderMixin):
         self,
         tokenizer: GemmaTokenizer | GemmaTokenizerFast,
         text_encoder: Gemma2PreTrainedModel,
-        vae: AutoencoderDC | AutoencoderKLWan,
+        vae: AutoencoderDC | AutoencoderKLLTX2Video | AutoencoderKLWan,
         transformer: SanaVideoTransformer3DModel,
         scheduler: DPMSolverMultistepScheduler,
     ):
@@ -223,8 +223,19 @@ class SanaVideoPipeline(DiffusionPipeline, SanaLoraLoaderMixin):
             tokenizer=tokenizer, text_encoder=text_encoder, vae=vae, transformer=transformer, scheduler=scheduler
         )
 
-        self.vae_scale_factor_temporal = self.vae.config.scale_factor_temporal if getattr(self, "vae", None) else 4
-        self.vae_scale_factor_spatial = self.vae.config.scale_factor_spatial if getattr(self, "vae", None) else 8
+        if getattr(self, "vae", None):
+            if isinstance(self.vae, AutoencoderKLLTX2Video):
+                self.vae_scale_factor_temporal = self.vae.config.temporal_compression_ratio
+                self.vae_scale_factor_spatial = self.vae.config.spatial_compression_ratio
+            elif isinstance(self.vae, (AutoencoderDC, AutoencoderKLWan)):
+                self.vae_scale_factor_temporal = self.vae.config.scale_factor_temporal
+                self.vae_scale_factor_spatial = self.vae.config.scale_factor_spatial
+            else:
+                self.vae_scale_factor_temporal = 4
+                self.vae_scale_factor_spatial = 8
+        else:
+            self.vae_scale_factor_temporal = 4
+            self.vae_scale_factor_spatial = 8
 
         self.vae_scale_factor = self.vae_scale_factor_spatial
 
@@ -985,14 +996,21 @@ class SanaVideoPipeline(DiffusionPipeline, SanaLoraLoaderMixin):
                 if is_torch_version(">=", "2.5.0")
                 else torch_accelerator_module.OutOfMemoryError
             )
-            latents_mean = (
-                torch.tensor(self.vae.config.latents_mean)
-                .view(1, self.vae.config.z_dim, 1, 1, 1)
-                .to(latents.device, latents.dtype)
-            )
-            latents_std = 1.0 / torch.tensor(self.vae.config.latents_std).view(1, self.vae.config.z_dim, 1, 1, 1).to(
-                latents.device, latents.dtype
-            )
+            if isinstance(self.vae, AutoencoderKLLTX2Video):
+                latents_mean = self.vae.latents_mean
+                latents_std = self.vae.latents_std
+                z_dim = self.vae.config.latent_channels
+            elif isinstance(self.vae, AutoencoderKLWan):
+                latents_mean = torch.tensor(self.vae.config.latents_mean)
+                latents_std = torch.tensor(self.vae.config.latents_std)
+                z_dim = self.vae.config.z_dim
+            else:
+                latents_mean = torch.zeros(latents.shape[1], device=latents.device, dtype=latents.dtype)
+                latents_std = torch.ones(latents.shape[1], device=latents.device, dtype=latents.dtype)
+                z_dim = latents.shape[1]
+
+            latents_mean = latents_mean.view(1, z_dim, 1, 1, 1).to(latents.device, latents.dtype)
+            latents_std = 1.0 / latents_std.view(1, z_dim, 1, 1, 1).to(latents.device, latents.dtype)
             latents = latents / latents_std + latents_mean
             try:
                 video = self.vae.decode(latents, return_dict=False)[0]

src/diffusers/pipelines/sana_video/pipeline_sana_video_i2v.py

@@ -26,7 +26,7 @@ from transformers import Gemma2PreTrainedModel, GemmaTokenizer, GemmaTokenizerFa
 from ...callbacks import MultiPipelineCallbacks, PipelineCallback
 from ...image_processor import PipelineImageInput
 from ...loaders import SanaLoraLoaderMixin
-from ...models import AutoencoderDC, AutoencoderKLWan, SanaVideoTransformer3DModel
+from ...models import AutoencoderDC, AutoencoderKLLTX2Video, AutoencoderKLWan, SanaVideoTransformer3DModel
 from ...schedulers import FlowMatchEulerDiscreteScheduler
 from ...utils import (
     BACKENDS_MAPPING,
@@ -184,7 +184,7 @@ class SanaImageToVideoPipeline(DiffusionPipeline, SanaLoraLoaderMixin):
             The tokenizer used to tokenize the prompt.
         text_encoder ([`Gemma2PreTrainedModel`]):
             Text encoder model to encode the input prompts.
-        vae ([`AutoencoderKLWan` or `AutoencoderDCAEV`]):
+        vae ([`AutoencoderKLWan`, `AutoencoderDC`, or `AutoencoderKLLTX2Video`]):
             Variational Auto-Encoder (VAE) Model to encode and decode videos to and from latent representations.
         transformer ([`SanaVideoTransformer3DModel`]):
             Conditional Transformer to denoise the input latents.
@@ -203,7 +203,7 @@ class SanaImageToVideoPipeline(DiffusionPipeline, SanaLoraLoaderMixin):
         self,
         tokenizer: GemmaTokenizer | GemmaTokenizerFast,
         text_encoder: Gemma2PreTrainedModel,
-        vae: AutoencoderDC | AutoencoderKLWan,
+        vae: AutoencoderDC | AutoencoderKLLTX2Video | AutoencoderKLWan,
         transformer: SanaVideoTransformer3DModel,
         scheduler: FlowMatchEulerDiscreteScheduler,
     ):
@@ -213,8 +213,19 @@ class SanaImageToVideoPipeline(DiffusionPipeline, SanaLoraLoaderMixin):
             tokenizer=tokenizer, text_encoder=text_encoder, vae=vae, transformer=transformer, scheduler=scheduler
         )
 
-        self.vae_scale_factor_temporal = self.vae.config.scale_factor_temporal if getattr(self, "vae", None) else 4
-        self.vae_scale_factor_spatial = self.vae.config.scale_factor_spatial if getattr(self, "vae", None) else 8
+        if getattr(self, "vae", None):
+            if isinstance(self.vae, AutoencoderKLLTX2Video):
+                self.vae_scale_factor_temporal = self.vae.config.temporal_compression_ratio
+                self.vae_scale_factor_spatial = self.vae.config.spatial_compression_ratio
+            elif isinstance(self.vae, (AutoencoderDC, AutoencoderKLWan)):
+                self.vae_scale_factor_temporal = self.vae.config.scale_factor_temporal
+                self.vae_scale_factor_spatial = self.vae.config.scale_factor_spatial
+            else:
+                self.vae_scale_factor_temporal = 4
+                self.vae_scale_factor_spatial = 8
+        else:
+            self.vae_scale_factor_temporal = 4
+            self.vae_scale_factor_spatial = 8
 
         self.vae_scale_factor = self.vae_scale_factor_spatial
 
@@ -687,14 +698,18 @@ class SanaImageToVideoPipeline(DiffusionPipeline, SanaLoraLoaderMixin):
             image_latents = retrieve_latents(self.vae.encode(image), sample_mode="argmax")
             image_latents = image_latents.repeat(batch_size, 1, 1, 1, 1)
 
-        latents_mean = (
-            torch.tensor(self.vae.config.latents_mean)
-            .view(1, -1, 1, 1, 1)
-            .to(image_latents.device, image_latents.dtype)
-        )
-        latents_std = 1.0 / torch.tensor(self.vae.config.latents_std).view(1, -1, 1, 1, 1).to(
-            image_latents.device, image_latents.dtype
-        )
+        if isinstance(self.vae, AutoencoderKLLTX2Video):
+            _latents_mean = self.vae.latents_mean
+            _latents_std = self.vae.latents_std
+        elif isinstance(self.vae, AutoencoderKLWan):
+            _latents_mean = torch.tensor(self.vae.config.latents_mean)
+            _latents_std = torch.tensor(self.vae.config.latents_std)
+        else:
+            _latents_mean = torch.zeros(image_latents.shape[1], device=image_latents.device, dtype=image_latents.dtype)
+            _latents_std = torch.ones(image_latents.shape[1], device=image_latents.device, dtype=image_latents.dtype)
+
+        latents_mean = _latents_mean.view(1, -1, 1, 1, 1).to(image_latents.device, image_latents.dtype)
+        latents_std = 1.0 / _latents_std.view(1, -1, 1, 1, 1).to(image_latents.device, image_latents.dtype)
         image_latents = (image_latents - latents_mean) * latents_std
 
         latents[:, :, 0:1] = image_latents.to(dtype)
@@ -1034,14 +1049,21 @@ class SanaImageToVideoPipeline(DiffusionPipeline, SanaLoraLoaderMixin):
                 if is_torch_version(">=", "2.5.0")
                 else torch_accelerator_module.OutOfMemoryError
             )
-            latents_mean = (
-                torch.tensor(self.vae.config.latents_mean)
-                .view(1, self.vae.config.z_dim, 1, 1, 1)
-                .to(latents.device, latents.dtype)
-            )
-            latents_std = 1.0 / torch.tensor(self.vae.config.latents_std).view(1, self.vae.config.z_dim, 1, 1, 1).to(
-                latents.device, latents.dtype
-            )
+            if isinstance(self.vae, AutoencoderKLLTX2Video):
+                latents_mean = self.vae.latents_mean
+                latents_std = self.vae.latents_std
+                z_dim = self.vae.config.latent_channels
+            elif isinstance(self.vae, AutoencoderKLWan):
+                latents_mean = torch.tensor(self.vae.config.latents_mean)
+                latents_std = torch.tensor(self.vae.config.latents_std)
+                z_dim = self.vae.config.z_dim
+            else:
+                latents_mean = torch.zeros(latents.shape[1], device=latents.device, dtype=latents.dtype)
+                latents_std = torch.ones(latents.shape[1], device=latents.device, dtype=latents.dtype)
+                z_dim = latents.shape[1]
+
+            latents_mean = latents_mean.view(1, z_dim, 1, 1, 1).to(latents.device, latents.dtype)
+            latents_std = 1.0 / latents_std.view(1, z_dim, 1, 1, 1).to(latents.device, latents.dtype)
             latents = latents / latents_std + latents_mean
             try:
                 video = self.vae.decode(latents, return_dict=False)[0]

tests/pipelines/helios/test_helios.py

@@ -139,9 +139,9 @@ class HeliosPipelineFastTests(PipelineTesterMixin, unittest.TestCase):
         generated_slice = torch.cat([generated_slice[:8], generated_slice[-8:]])
         self.assertTrue(torch.allclose(generated_slice, expected_slice, atol=1e-3))
 
-    # Override to set a more lenient max diff threshold.
+    @unittest.skip("Helios uses a lot of mixed precision internally, which is not suitable for this test case")
     def test_save_load_float16(self):
-        super().test_save_load_float16(expected_max_diff=0.03)
+        pass
 
     @unittest.skip("Test not supported")
     def test_attention_slicing_forward_pass(self):