Debias Estimation loss (#889)

* update for bnb 0.41.1

* fixed generate_controlnet_subsets_config for training

* Revert "update for bnb 0.41.1"

This reverts commit 70bd3612d8.

* add debiased_estimation_loss

* add train_network

* Revert "add train_network"

This reverts commit 6539363c5c.

* Update train_network.py

library/custom_train_functions.py

@@ -86,6 +86,12 @@ def add_v_prediction_like_loss(loss, timesteps, noise_scheduler, v_pred_like_los
     loss = loss + loss / scale * v_pred_like_loss
     return loss
 
+def apply_debiased_estimation(loss, timesteps, noise_scheduler):
+    snr_t = torch.stack([noise_scheduler.all_snr[t] for t in timesteps])  # batch_size
+    snr_t = torch.minimum(snr_t, torch.ones_like(snr_t) * 1000)  # if timestep is 0, snr_t is inf, so limit it to 1000
+    weight = 1/torch.sqrt(snr_t)
+    loss = weight * loss
+    return loss
 
 # TODO train_utilと分散しているのでどちらかに寄せる
 
@@ -108,6 +114,11 @@ def add_custom_train_arguments(parser: argparse.ArgumentParser, support_weighted
         default=None,
         help="add v-prediction like loss multiplied by this value / v-prediction lossをこの値をかけたものをlossに加算する",
     )
+    parser.add_argument(
+        "--debiased_estimation_loss",
+        action="store_true",
+        help="debiased estimation loss / debiased estimation loss",
+    )
     if support_weighted_captions:
         parser.add_argument(
             "--weighted_captions",