[Wuerstchen] fix combined pipeline's num_images_per_prompt (#4989)

* fix encode_prompt

* added prompt_embeds and negative_prompt_embeds

* prompt_embeds for the prior only

src/diffusers/pipelines/wuerstchen/pipeline_wuerstchen.py

@@ -330,7 +330,11 @@ class WuerstchenDecoderPipeline(DiffusionPipeline):
 
         # 2. Encode caption
         prompt_embeds, negative_prompt_embeds = self.encode_prompt(
-            prompt, device, num_images_per_prompt, do_classifier_free_guidance, negative_prompt
+            prompt,
+            device,
+            image_embeddings.size(0) * num_images_per_prompt,
+            do_classifier_free_guidance,
+            negative_prompt,
         )
         text_encoder_hidden_states = (
             torch.cat([prompt_embeds, negative_prompt_embeds]) if negative_prompt_embeds is not None else prompt_embeds

src/diffusers/pipelines/wuerstchen/pipeline_wuerstchen_combined.py

@@ -154,6 +154,8 @@ class WuerstchenCombinedPipeline(DiffusionPipeline):
         decoder_timesteps: Optional[List[float]] = None,
         decoder_guidance_scale: float = 0.0,
         negative_prompt: Optional[Union[str, List[str]]] = None,
+        prompt_embeds: Optional[torch.FloatTensor] = None,
+        negative_prompt_embeds: Optional[torch.FloatTensor] = None,
         num_images_per_prompt: int = 1,
         generator: Optional[Union[torch.Generator, List[torch.Generator]]] = None,
         latents: Optional[torch.FloatTensor] = None,
@@ -165,10 +167,17 @@ class WuerstchenCombinedPipeline(DiffusionPipeline):
 
         Args:
             prompt (`str` or `List[str]`):
-                The prompt or prompts to guide the image generation.
+                The prompt or prompts to guide the image generation for the prior and decoder.
             negative_prompt (`str` or `List[str]`, *optional*):
                 The prompt or prompts not to guide the image generation. Ignored when not using guidance (i.e., ignored
                 if `guidance_scale` is less than `1`).
+            prompt_embeds (`torch.FloatTensor`, *optional*):
+                Pre-generated text embeddings for the prior. Can be used to easily tweak text inputs, *e.g.* prompt weighting. If not
+                provided, text embeddings will be generated from `prompt` input argument.
+            negative_prompt_embeds (`torch.FloatTensor`, *optional*):
+                Pre-generated negative text embeddings for the prior. Can be used to easily tweak text inputs, *e.g.* prompt
+                weighting. If not provided, negative_prompt_embeds will be generated from `negative_prompt` input
+                argument.
             num_images_per_prompt (`int`, *optional*, defaults to 1):
                 The number of images to generate per prompt.
             height (`int`, *optional*, defaults to 512):
@@ -221,13 +230,15 @@ class WuerstchenCombinedPipeline(DiffusionPipeline):
             otherwise a `tuple`. When returning a tuple, the first element is a list with the generated images.
         """
         prior_outputs = self.prior_pipe(
-            prompt=prompt,
+            prompt=prompt if prompt_embeds is None else None,
             height=height,
             width=width,
             num_inference_steps=prior_num_inference_steps,
             timesteps=prior_timesteps,
             guidance_scale=prior_guidance_scale,
-            negative_prompt=negative_prompt,
+            negative_prompt=negative_prompt if negative_prompt_embeds is None else None,
+            prompt_embeds=prompt_embeds,
+            negative_prompt_embeds=negative_prompt_embeds,
             num_images_per_prompt=num_images_per_prompt,
             generator=generator,
             latents=latents,

src/diffusers/pipelines/wuerstchen/pipeline_wuerstchen_prior.py

@@ -150,13 +150,22 @@ class WuerstchenPriorPipeline(DiffusionPipeline):
 
     def encode_prompt(
         self,
-        prompt,
         device,
         num_images_per_prompt,
         do_classifier_free_guidance,
+        prompt=None,
         negative_prompt=None,
+        prompt_embeds: Optional[torch.FloatTensor] = None,
+        negative_prompt_embeds: Optional[torch.FloatTensor] = None,
     ):
-        batch_size = len(prompt) if isinstance(prompt, list) else 1
+        if prompt is not None and isinstance(prompt, str):
+            batch_size = 1
+        elif prompt is not None and isinstance(prompt, list):
+            batch_size = len(prompt)
+        else:
+            batch_size = prompt_embeds.shape[0]
+
+        if prompt_embeds is None:
             # get prompt text embeddings
             text_inputs = self.tokenizer(
                 prompt,
@@ -170,8 +179,12 @@ class WuerstchenPriorPipeline(DiffusionPipeline):
 
             untruncated_ids = self.tokenizer(prompt, padding="longest", return_tensors="pt").input_ids
 
-        if untruncated_ids.shape[-1] >= text_input_ids.shape[-1] and not torch.equal(text_input_ids, untruncated_ids):
-            removed_text = self.tokenizer.batch_decode(untruncated_ids[:, self.tokenizer.model_max_length - 1 : -1])
+            if untruncated_ids.shape[-1] >= text_input_ids.shape[-1] and not torch.equal(
+                text_input_ids, untruncated_ids
+            ):
+                removed_text = self.tokenizer.batch_decode(
+                    untruncated_ids[:, self.tokenizer.model_max_length - 1 : -1]
+                )
                 logger.warning(
                     "The following part of your input was truncated because CLIP can only handle sequences up to"
                     f" {self.tokenizer.model_max_length} tokens: {removed_text}"
@@ -179,12 +192,15 @@ class WuerstchenPriorPipeline(DiffusionPipeline):
                 text_input_ids = text_input_ids[:, : self.tokenizer.model_max_length]
                 attention_mask = attention_mask[:, : self.tokenizer.model_max_length]
 
-        text_encoder_output = self.text_encoder(text_input_ids.to(device), attention_mask=attention_mask.to(device))
-        text_encoder_hidden_states = text_encoder_output.last_hidden_state
-        text_encoder_hidden_states = text_encoder_hidden_states.repeat_interleave(num_images_per_prompt, dim=0)
+            text_encoder_output = self.text_encoder(
+                text_input_ids.to(device), attention_mask=attention_mask.to(device)
+            )
+            prompt_embeds = text_encoder_output.last_hidden_state
 
-        uncond_text_encoder_hidden_states = None
-        if do_classifier_free_guidance:
+        prompt_embeds = prompt_embeds.to(dtype=self.text_encoder.dtype, device=device)
+        prompt_embeds = prompt_embeds.repeat_interleave(num_images_per_prompt, dim=0)
+
+        if negative_prompt_embeds is None and do_classifier_free_guidance:
             uncond_tokens: List[str]
             if negative_prompt is None:
                 uncond_tokens = [""] * batch_size
@@ -215,17 +231,17 @@ class WuerstchenPriorPipeline(DiffusionPipeline):
                 uncond_input.input_ids.to(device), attention_mask=uncond_input.attention_mask.to(device)
             )
 
-            uncond_text_encoder_hidden_states = negative_prompt_embeds_text_encoder_output.last_hidden_state
+            negative_prompt_embeds = negative_prompt_embeds_text_encoder_output.last_hidden_state
 
+        if do_classifier_free_guidance:
             # duplicate unconditional embeddings for each generation per prompt, using mps friendly method
-            seq_len = uncond_text_encoder_hidden_states.shape[1]
-            uncond_text_encoder_hidden_states = uncond_text_encoder_hidden_states.repeat(1, num_images_per_prompt, 1)
-            uncond_text_encoder_hidden_states = uncond_text_encoder_hidden_states.view(
-                batch_size * num_images_per_prompt, seq_len, -1
-            )
+            seq_len = negative_prompt_embeds.shape[1]
+            negative_prompt_embeds = negative_prompt_embeds.to(dtype=self.text_encoder.dtype, device=device)
+            negative_prompt_embeds = negative_prompt_embeds.repeat(1, num_images_per_prompt, 1)
+            negative_prompt_embeds = negative_prompt_embeds.view(batch_size * num_images_per_prompt, seq_len, -1)
             # done duplicates
 
-        return text_encoder_hidden_states, uncond_text_encoder_hidden_states
+        return prompt_embeds, negative_prompt_embeds
 
     def check_inputs(
         self,
@@ -264,13 +280,15 @@ class WuerstchenPriorPipeline(DiffusionPipeline):
     @replace_example_docstring(EXAMPLE_DOC_STRING)
     def __call__(
         self,
-        prompt: Union[str, List[str]] = None,
+        prompt: Optional[Union[str, List[str]]] = None,
         height: int = 1024,
         width: int = 1024,
         num_inference_steps: int = 60,
         timesteps: List[float] = None,
         guidance_scale: float = 8.0,
         negative_prompt: Optional[Union[str, List[str]]] = None,
+        prompt_embeds: Optional[torch.FloatTensor] = None,
+        negative_prompt_embeds: Optional[torch.FloatTensor] = None,
         num_images_per_prompt: Optional[int] = 1,
         generator: Optional[Union[torch.Generator, List[torch.Generator]]] = None,
         latents: Optional[torch.FloatTensor] = None,
@@ -304,6 +322,13 @@ class WuerstchenPriorPipeline(DiffusionPipeline):
             negative_prompt (`str` or `List[str]`, *optional*):
                 The prompt or prompts not to guide the image generation. Ignored when not using guidance (i.e., ignored
                 if `decoder_guidance_scale` is less than `1`).
+            prompt_embeds (`torch.FloatTensor`, *optional*):
+                Pre-generated text embeddings. Can be used to easily tweak text inputs, *e.g.* prompt weighting. If not
+                provided, text embeddings will be generated from `prompt` input argument.
+            negative_prompt_embeds (`torch.FloatTensor`, *optional*):
+                Pre-generated negative text embeddings. Can be used to easily tweak text inputs, *e.g.* prompt
+                weighting. If not provided, negative_prompt_embeds will be generated from `negative_prompt` input
+                argument.
             num_images_per_prompt (`int`, *optional*, defaults to 1):
                 The number of images to generate per prompt.
             generator (`torch.Generator` or `List[torch.Generator]`, *optional*):
@@ -345,7 +370,13 @@ class WuerstchenPriorPipeline(DiffusionPipeline):
 
         # 2. Encode caption
         prompt_embeds, negative_prompt_embeds = self.encode_prompt(
-            prompt, device, num_images_per_prompt, do_classifier_free_guidance, negative_prompt
+            prompt=prompt,
+            device=device,
+            num_images_per_prompt=num_images_per_prompt,
+            do_classifier_free_guidance=do_classifier_free_guidance,
+            negative_prompt=negative_prompt,
+            prompt_embeds=prompt_embeds,
+            negative_prompt_embeds=negative_prompt_embeds,
         )
 
         # For classifier free guidance, we need to do two forward passes.