add GradTTSScheduler

src/diffusers/__init__.py

@@ -11,5 +11,5 @@ from .models.unet_ldm import UNetLDMModel
 from .models.unet_grad_tts import UNetGradTTSModel
 from .pipeline_utils import DiffusionPipeline
 from .pipelines import DDIM, DDPM, GLIDE, LatentDiffusion, PNDM, BDDM
-from .schedulers import DDIMScheduler, DDPMScheduler, SchedulerMixin, PNDMScheduler
+from .schedulers import DDIMScheduler, DDPMScheduler, SchedulerMixin, PNDMScheduler, GradTTSScheduler
 from .schedulers.classifier_free_guidance import ClassifierFreeGuidanceScheduler

src/diffusers/schedulers/__init__.py

@@ -20,4 +20,5 @@ from .classifier_free_guidance import ClassifierFreeGuidanceScheduler
 from .scheduling_ddim import DDIMScheduler
 from .scheduling_ddpm import DDPMScheduler
 from .scheduling_pndm import PNDMScheduler
+from .scheduling_grad_tts import GradTTSScheduler
 from .scheduling_utils import SchedulerMixin

src/diffusers/schedulers/scheduling_grad_tts.py

@@ -0,0 +1,52 @@
+# Copyright 2022 The HuggingFace Team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+import math
+
+import numpy as np
+
+from ..configuration_utils import ConfigMixin
+from .scheduling_utils import SchedulerMixin
+
+
+class GradTTSScheduler(SchedulerMixin, ConfigMixin):
+    def __init__(
+        self,
+        timesteps=1000,
+        beta_start=0.0001,
+        beta_end=0.02,
+        tensor_format="np",
+    ):
+        super().__init__()
+        self.register(
+            timesteps=timesteps,
+            beta_start=beta_start,
+            beta_end=beta_end,
+        )
+        self.timesteps = int(timesteps)
+
+        self.set_format(tensor_format=tensor_format)
+    
+    def sample_noise(self, timestep):
+        noise = self.beta_start + (self.beta_end - self.beta_start) * timestep
+        return noise
+    
+    def step(self, xt, residual, mu, h, timestep):
+        noise_t = self.sample_noise(timestep)
+        dxt = 0.5 * (mu - xt - residual)
+        dxt = dxt * noise_t * h
+        xt = xt - dxt
+        return xt
+
+    def __len__(self):
+        return self.timesteps