consistency decoder (#5694)

* consistency decoder

* rename

* Apply suggestions from code review

Co-authored-by: Sayak Paul <[email protected]>

* Update src/diffusers/pipelines/consistency_models/pipeline_consistency_models.py

* uP

* Apply suggestions from code review

* uP

* uP

* uP

---------

Co-authored-by: Patrick von Platen <[email protected]>
Co-authored-by: Sayak Paul <[email protected]>

Author: 3 people

docs/source/en/_toctree.yml

@@ -200,6 +200,8 @@
       title: AsymmetricAutoencoderKL
     - local: api/models/autoencoder_tiny
       title: Tiny AutoEncoder
+    - local: api/models/consistency_decoder_vae
+      title: ConsistencyDecoderVAE
     - local: api/models/transformer2d
       title: Transformer2D
     - local: api/models/transformer_temporal
@@ -344,6 +346,8 @@
       title: Overview
     - local: api/schedulers/cm_stochastic_iterative
       title: CMStochasticIterativeScheduler
+    - local: api/schedulers/consistency_decoder
+      title: ConsistencyDecoderScheduler
     - local: api/schedulers/ddim_inverse
       title: DDIMInverseScheduler
     - local: api/schedulers/ddim

docs/source/en/api/models/consistency_decoder_vae.md

@@ -0,0 +1,18 @@
+# Consistency Decoder
+
+Consistency decoder can be used to decode the latents from the denoising UNet in the [`StableDiffusionPipeline`]. This decoder was introduced in the [DALL-E 3 technical report](https://openai.com/dall-e-3). 
+
+The original codebase can be found at [openai/consistencydecoder](https://github.com/openai/consistencydecoder).
+
+<Tip warning={true}>
+
+Inference is only supported for 2 iterations as of now.
+
+</Tip>
+
+The pipeline could not have been contributed without the help of [madebyollin](https://github.com/madebyollin) and [mrsteyk](https://github.com/mrsteyk) from [this issue](https://github.com/openai/consistencydecoder/issues/1).
+
+## ConsistencyDecoderVAE
+[[autodoc]] ConsistencyDecoderVAE
+    - all
+    - decode

docs/source/en/api/schedulers/consistency_decoder.md

@@ -0,0 +1,9 @@
+# ConsistencyDecoderScheduler
+
+This scheduler is a part of the [`ConsistencyDecoderPipeline`] and was introduced in [DALL-E 3](https://openai.com/dall-e-3). 
+
+The original codebase can be found at [openai/consistency_models](https://github.com/openai/consistency_models).
+
+
+## ConsistencyDecoderScheduler
+[[autodoc]] schedulers.scheduling_consistency_decoder.ConsistencyDecoderScheduler