[wan2.2] add 5b i2v (#12006)

* add 5b ti2v

* remove a copy

* Update src/diffusers/pipelines/wan/pipeline_wan_i2v.py
Co-authored-by: Aryan <aryan@huggingface.co>

* Apply suggestions from code review

---------
Co-authored-by: Aryan <aryan@huggingface.co>

src/diffusers/pipelines/skyreels_v2/pipeline_skyreels_v2_i2v.py

@@ -370,7 +370,6 @@ class SkyReelsV2ImageToVideoPipeline(DiffusionPipeline, SkyReelsV2LoraLoaderMixi
         ):
             raise ValueError(f"`negative_prompt` has to be of type `str` or `list` but is {type(negative_prompt)}")
 
-    # Copied from diffusers.pipelines.wan.pipeline_wan_i2v.WanImageToVideoPipeline.prepare_latents
     def prepare_latents(
         self,
         image: PipelineImageInput,

src/diffusers/pipelines/wan/pipeline_wan_i2v.py

@@ -175,6 +175,7 @@ class WanImageToVideoPipeline(DiffusionPipeline, WanLoraLoaderMixin):
         image_encoder: CLIPVisionModel = None,
         transformer_2: WanTransformer3DModel = None,
         boundary_ratio: Optional[float] = None,
+        expand_timesteps: bool = False,
     ):
         super().__init__()
 
@@ -188,10 +189,10 @@ class WanImageToVideoPipeline(DiffusionPipeline, WanLoraLoaderMixin):
             image_processor=image_processor,
             transformer_2=transformer_2,
         )
-        self.register_to_config(boundary_ratio=boundary_ratio)
+        self.register_to_config(boundary_ratio=boundary_ratio, expand_timesteps=expand_timesteps)
 
-        self.vae_scale_factor_temporal = 2 ** sum(self.vae.temperal_downsample) if getattr(self, "vae", None) else 4
-        self.vae_scale_factor_spatial = 2 ** len(self.vae.temperal_downsample) if getattr(self, "vae", None) else 8
+        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
         self.video_processor = VideoProcessor(vae_scale_factor=self.vae_scale_factor_spatial)
         self.image_processor = image_processor
 
@@ -419,8 +420,12 @@ class WanImageToVideoPipeline(DiffusionPipeline, WanLoraLoaderMixin):
         else:
             latents = latents.to(device=device, dtype=dtype)
 
-        image = image.unsqueeze(2)
-        if last_image is None:
+        image = image.unsqueeze(2)  # [batch_size, channels, 1, height, width]
+
+        if self.config.expand_timesteps:
+            video_condition = image
+
+        elif last_image is None:
             video_condition = torch.cat(
                 [image, image.new_zeros(image.shape[0], image.shape[1], num_frames - 1, height, width)], dim=2
             )
@@ -453,6 +458,13 @@ class WanImageToVideoPipeline(DiffusionPipeline, WanLoraLoaderMixin):
         latent_condition = latent_condition.to(dtype)
         latent_condition = (latent_condition - latents_mean) * latents_std
 
+        if self.config.expand_timesteps:
+            first_frame_mask = torch.ones(
+                1, 1, num_latent_frames, latent_height, latent_width, dtype=dtype, device=device
+            )
+            first_frame_mask[:, :, 0] = 0
+            return latents, latent_condition, first_frame_mask
+
         mask_lat_size = torch.ones(batch_size, 1, num_frames, latent_height, latent_width)
 
         if last_image is None:
@@ -662,7 +674,7 @@ class WanImageToVideoPipeline(DiffusionPipeline, WanLoraLoaderMixin):
         if negative_prompt_embeds is not None:
             negative_prompt_embeds = negative_prompt_embeds.to(transformer_dtype)
 
-        if self.config.boundary_ratio is None:
+        if self.config.boundary_ratio is None and not self.config.expand_timesteps:
             if image_embeds is None:
                 if last_image is None:
                     image_embeds = self.encode_image(image, device)
@@ -682,7 +694,8 @@ class WanImageToVideoPipeline(DiffusionPipeline, WanLoraLoaderMixin):
             last_image = self.video_processor.preprocess(last_image, height=height, width=width).to(
                 device, dtype=torch.float32
             )
-        latents, condition = self.prepare_latents(
+
+        latents_outputs = self.prepare_latents(
             image,
             batch_size * num_videos_per_prompt,
             num_channels_latents,
@@ -695,6 +708,10 @@ class WanImageToVideoPipeline(DiffusionPipeline, WanLoraLoaderMixin):
             latents,
             last_image,
         )
+        if self.config.expand_timesteps:
+            latents, condition, first_frame_mask = latents_outputs
+        else:
+            latents, condition = latents_outputs
 
         # 6. Denoising loop
         num_warmup_steps = len(timesteps) - num_inference_steps * self.scheduler.order
@@ -721,8 +738,17 @@ class WanImageToVideoPipeline(DiffusionPipeline, WanLoraLoaderMixin):
                     current_model = self.transformer_2
                     current_guidance_scale = guidance_scale_2
 
-                latent_model_input = torch.cat([latents, condition], dim=1).to(transformer_dtype)
-                timestep = t.expand(latents.shape[0])
+                if self.config.expand_timesteps:
+                    latent_model_input = (1 - first_frame_mask) * condition + first_frame_mask * latents
+                    latent_model_input = latent_model_input.to(transformer_dtype)
+
+                    # seq_len: num_latent_frames * (latent_height // patch_size) * (latent_width // patch_size)
+                    temp_ts = (first_frame_mask[0][0][:, ::2, ::2] * t).flatten()
+                    # batch_size, seq_len
+                    timestep = temp_ts.unsqueeze(0).expand(latents.shape[0], -1)
+                else:
+                    latent_model_input = torch.cat([latents, condition], dim=1).to(transformer_dtype)
+                    timestep = t.expand(latents.shape[0])
 
                 noise_pred = current_model(
                     hidden_states=latent_model_input,
@@ -766,6 +792,9 @@ class WanImageToVideoPipeline(DiffusionPipeline, WanLoraLoaderMixin):
 
         self._current_timestep = None
 
+        if self.config.expand_timesteps:
+            latents = (1 - first_frame_mask) * condition + first_frame_mask * latents
+
         if not output_type == "latent":
             latents = latents.to(self.vae.dtype)
             latents_mean = (