style changes for #14979

modules/sd_models.py

@@ -552,36 +552,48 @@ def repair_config(sd_config):
         karlo_path = os.path.join(paths.models_path, 'karlo')
         sd_config.model.params.noise_aug_config.params.clip_stats_path = sd_config.model.params.noise_aug_config.params.clip_stats_path.replace("checkpoints/karlo_models", karlo_path)
 
+
+def rescale_zero_terminal_snr_abar(alphas_cumprod):
+    alphas_bar_sqrt = alphas_cumprod.sqrt()
+
+    # Store old values.
+    alphas_bar_sqrt_0 = alphas_bar_sqrt[0].clone()
+    alphas_bar_sqrt_T = alphas_bar_sqrt[-1].clone()
+
+    # Shift so the last timestep is zero.
+    alphas_bar_sqrt -= (alphas_bar_sqrt_T)
+
+    # Scale so the first timestep is back to the old value.
+    alphas_bar_sqrt *= alphas_bar_sqrt_0 / (alphas_bar_sqrt_0 - alphas_bar_sqrt_T)
+
+    # Convert alphas_bar_sqrt to betas
+    alphas_bar = alphas_bar_sqrt ** 2  # Revert sqrt
+    alphas_bar[-1] = 4.8973451890853435e-08
+    return alphas_bar
+
+
 def apply_alpha_schedule_override(sd_model, p=None):
-    def rescale_zero_terminal_snr_abar(alphas_cumprod):
-        alphas_bar_sqrt = alphas_cumprod.sqrt()
-
-        # Store old values.
-        alphas_bar_sqrt_0 = alphas_bar_sqrt[0].clone()
-        alphas_bar_sqrt_T = alphas_bar_sqrt[-1].clone()
-
-        # Shift so the last timestep is zero.
-        alphas_bar_sqrt -= (alphas_bar_sqrt_T)
-
-        # Scale so the first timestep is back to the old value.
-        alphas_bar_sqrt *= alphas_bar_sqrt_0 / (alphas_bar_sqrt_0 - alphas_bar_sqrt_T)
-
-        # Convert alphas_bar_sqrt to betas
-        alphas_bar = alphas_bar_sqrt**2  # Revert sqrt
-        alphas_bar[-1] = 4.8973451890853435e-08
-        return alphas_bar
-
-    if hasattr(sd_model, 'alphas_cumprod') and hasattr(sd_model, 'alphas_cumprod_original'):
-        sd_model.alphas_cumprod = sd_model.alphas_cumprod_original.to(shared.device)
-
-        if opts.use_downcasted_alpha_bar:
-            if p is not None:
-                p.extra_generation_params['Downcast alphas_cumprod'] = opts.use_downcasted_alpha_bar
-            sd_model.alphas_cumprod = sd_model.alphas_cumprod.half().to(shared.device)
-        if opts.sd_noise_schedule == "Zero Terminal SNR":
-            if p is not None:
-                p.extra_generation_params['Noise Schedule'] = opts.sd_noise_schedule
-            sd_model.alphas_cumprod = rescale_zero_terminal_snr_abar(sd_model.alphas_cumprod).to(shared.device)
+    """
+    Applies an override to the alpha schedule of the model according to settings.
+    - downcasts the alpha schedule to half precision
+    - rescales the alpha schedule to have zero terminal SNR
+    """
+
+    if not hasattr(sd_model, 'alphas_cumprod') or not hasattr(sd_model, 'alphas_cumprod_original'):
+        return
+
+    sd_model.alphas_cumprod = sd_model.alphas_cumprod_original.to(shared.device)
+
+    if opts.use_downcasted_alpha_bar:
+        if p is not None:
+            p.extra_generation_params['Downcast alphas_cumprod'] = opts.use_downcasted_alpha_bar
+        sd_model.alphas_cumprod = sd_model.alphas_cumprod.half().to(shared.device)
+
+    if opts.sd_noise_schedule == "Zero Terminal SNR":
+        if p is not None:
+            p.extra_generation_params['Noise Schedule'] = opts.sd_noise_schedule
+        sd_model.alphas_cumprod = rescale_zero_terminal_snr_abar(sd_model.alphas_cumprod).to(shared.device)
+
 
 sd1_clip_weight = 'cond_stage_model.transformer.text_model.embeddings.token_embedding.weight'
 sd2_clip_weight = 'cond_stage_model.model.transformer.resblocks.0.attn.in_proj_weight'