Fix LCM Stable Diffusion distillation bug related to parsing unet_time_cond_proj_dim (#5893)

* Fix bug related to parsing unet_time_cond_proj_dim.

* Fix analogous bug in the SD-XL LCM distillation script.

examples/consistency_distillation/train_lcm_distill_sd_wds.py

@@ -657,6 +657,15 @@ def parse_args():
         default=0.001,
         help="The huber loss parameter. Only used if `--loss_type=huber`.",
     )
+    parser.add_argument(
+        "--unet_time_cond_proj_dim",
+        type=int,
+        default=256,
+        help=(
+            "The dimension of the guidance scale embedding in the U-Net, which will be used if the teacher U-Net"
+            " does not have `time_cond_proj_dim` set."
+        ),
+    )
     # ----Exponential Moving Average (EMA)----
     parser.add_argument(
         "--ema_decay",
@@ -1138,7 +1147,7 @@ def main(args):
 
                 # 20.4.6. Sample a random guidance scale w from U[w_min, w_max] and embed it
                 w = (args.w_max - args.w_min) * torch.rand((bsz,)) + args.w_min
-                w_embedding = guidance_scale_embedding(w, embedding_dim=args.unet_time_cond_proj_dim)
+                w_embedding = guidance_scale_embedding(w, embedding_dim=unet.config.time_cond_proj_dim)
                 w = w.reshape(bsz, 1, 1, 1)
                 # Move to U-Net device and dtype
                 w = w.to(device=latents.device, dtype=latents.dtype)

examples/consistency_distillation/train_lcm_distill_sdxl_wds.py

@@ -677,6 +677,15 @@ def parse_args():
         default=0.001,
         help="The huber loss parameter. Only used if `--loss_type=huber`.",
     )
+    parser.add_argument(
+        "--unet_time_cond_proj_dim",
+        type=int,
+        default=256,
+        help=(
+            "The dimension of the guidance scale embedding in the U-Net, which will be used if the teacher U-Net"
+            " does not have `time_cond_proj_dim` set."
+        ),
+    )
     # ----Exponential Moving Average (EMA)----
     parser.add_argument(
         "--ema_decay",
@@ -1233,6 +1242,7 @@ def main(args):
 
                 # 20.4.6. Sample a random guidance scale w from U[w_min, w_max] and embed it
                 w = (args.w_max - args.w_min) * torch.rand((bsz,)) + args.w_min
+                w_embedding = guidance_scale_embedding(w, embedding_dim=unet.config.time_cond_proj_dim)
                 w = w.reshape(bsz, 1, 1, 1)
                 w = w.to(device=latents.device, dtype=latents.dtype)
 
@@ -1243,7 +1253,7 @@ def main(args):
                 noise_pred = unet(
                     noisy_model_input,
                     start_timesteps,
-                    timestep_cond=None,
+                    timestep_cond=w_embedding,
                     encoder_hidden_states=prompt_embeds.float(),
                     added_cond_kwargs=encoded_text,
                 ).sample
@@ -1308,7 +1318,7 @@ def main(args):
                         target_noise_pred = target_unet(
                             x_prev.float(),
                             timesteps,
-                            timestep_cond=None,
+                            timestep_cond=w_embedding,
                             encoder_hidden_states=prompt_embeds.float(),
                             added_cond_kwargs=encoded_text,
                         ).sample