Add Echo modular pipeline

docs/source/en/_toctree.yml

@@ -555,6 +555,8 @@
         title: DreamLite
       - local: api/pipelines/easyanimate
         title: EasyAnimate
+      - local: api/pipelines/echo
+        title: Echo
       - local: api/pipelines/ernie_image
         title: ERNIE-Image
       - local: api/pipelines/flux

docs/source/en/api/pipelines/echo.md

@@ -0,0 +1,106 @@
+<!-- Copyright 2026 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. -->
+
+# Echo
+
+[Echo](https://github.com/jd-opensource/JoyAI-Echo) is a long-video generation model. It adds an optional clean first
+frame, ordered image/audio memory slots, and a stochastic few-step Distribution Matching Distillation (DMD) sampler.
+The pipeline generates synchronized video and audio.
+
+Echo is implemented as a Modular Pipeline so its text encoding, memory conditioning, stochastic DMD denoising, and
+decoding blocks can be run as a complete workflow or composed independently.
+
+## Convert the checkpoint
+
+Convert the BF16 Echo release checkpoint before loading it. The converter reuses the Gemma text encoder and
+tokenizer directly from `google/gemma-3-12b-it`.
+
+```bash
+python scripts/convert_echo_to_diffusers.py \
+  --checkpoint /path/to/echo15_full_dmd \
+  --output-path /path/to/Echo-Diffusers \
+  --repo-id Echo-Team/JoyAI-Echo
+```
+
+The Gemma repository is gated, so users must accept its license and authenticate with Hugging Face before loading the
+pipeline. Pass a different `--base-model` only when the compatible Gemma model and tokenizer are stored together at
+that repository or path root. `--repo-id` records portable Hub references for the converted Echo components; without
+it, the index targets the local output path.
+
+## Inference
+
+The released model uses 241 frames in its long-video example. The video RoPE coordinates remain at the training rate
+of 24 fps, independently of the output container rate.
+
+```py
+import torch
+import torchaudio
+from PIL import Image
+
+from diffusers import ComponentsManager, ModularPipeline
+from diffusers.utils import encode_video
+
+
+model_path = "/path/to/Echo-Diffusers"
+manager = ComponentsManager()
+pipe = ModularPipeline.from_pretrained(model_path, components_manager=manager)
+pipe.load_components(dtype={"default": torch.bfloat16, "audio_vae": torch.float32})
+manager.enable_auto_cpu_offload(device="cuda")
+pipe.vae.enable_tiling()
+
+first_frame = Image.open("first_frame.png").convert("RGB")
+memory_images = [Image.open(path).convert("RGB") for path in ["memory_0.png", "memory_1.png"]]
+memory_audio_with_rates = [torchaudio.load(path) for path in ["memory_0.wav", "memory_1.wav"]]
+memory_audio = [waveform for waveform, _ in memory_audio_with_rates]
+memory_audio_rates = [sample_rate for _, sample_rate in memory_audio_with_rates]
+
+output = pipe(
+    prompt="A cinematic dialogue scene in a quiet cafe.",
+    image=first_frame,
+    memory_images=memory_images,
+    memory_audio_waveforms=memory_audio,
+    memory_audio_sample_rates=memory_audio_rates,
+    width=1280,
+    height=736,
+    num_frames=241,
+    frame_rate=25.0,
+    model_frame_rate=24.0,
+    generator=torch.Generator(device="cuda").manual_seed(42),
+    output_type="np",
+    output=["videos", "audio"],
+)
+
+encode_video(
+    output["videos"][0],
+    fps=25,
+    audio=output["audio"][0].float().cpu(),
+    audio_sample_rate=pipe.vocoder.config.output_sampling_rate,
+    output_path="echo.mp4",
+)
+```
+
+The default DMD sigma schedule is the released eight-step schedule. It predicts x0 at every step and re-noises with
+fresh Gaussian noise at the next sigma, so a seeded `torch.Generator` controls both the initial noise and all
+intermediate re-noising.
+
+Raw audio-memory encoding requires `torchaudio`. For reference parity, keep `audio_vae` in FP32 as shown above.
+Modular workflows can cache and reuse the condition encoder's packed token outputs by running that block separately.
+
+## EchoModularPipeline
+
+[[autodoc]] EchoModularPipeline
+
+## EchoBlocks
+
+[[autodoc]] EchoBlocks

scripts/convert_echo_to_diffusers.py

@@ -0,0 +1,179 @@
+#!/usr/bin/env python3
+"""Convert the Echo BF16 release checkpoint into a Diffusers Modular Pipeline repository."""
+
+import argparse
+import gc
+import json
+from pathlib import Path
+
+import torch
+from convert_ltx2_to_diffusers import (
+    convert_ltx2_audio_vae,
+    convert_ltx2_connectors,
+    convert_ltx2_transformer,
+    convert_ltx2_video_vae,
+    convert_ltx2_vocoder,
+    get_model_state_dict_from_combined_ckpt,
+)
+from safetensors.torch import load_file
+
+from diffusers import __version__
+
+
+def resolve_checkpoint(path: Path) -> Path:
+    path = path.expanduser().resolve()
+    if path.is_file():
+        return path
+
+    manifest_path = path / "checkpoint.json"
+    if not manifest_path.is_file():
+        raise FileNotFoundError(f"Checkpoint manifest not found: {manifest_path}")
+    manifest = json.loads(manifest_path.read_text(encoding="utf-8"))
+    precision = str(manifest.get("precision", "")).lower()
+    if precision not in {"bf16", "bfloat16"}:
+        raise ValueError(
+            "Echo conversion supports the BF16 release only. The FP8 and FP4 releases use custom packed "
+            f"kernels and cannot be represented by this converter, got precision={precision!r}."
+        )
+    model_filename = manifest.get("files", {}).get("model")
+    if not model_filename:
+        raise ValueError(f"Checkpoint manifest has no `files.model`: {manifest_path}")
+    return path / model_filename
+
+
+def save_component(model, output_path: Path, name: str, max_shard_size: str) -> None:
+    model.to(torch.bfloat16).save_pretrained(
+        output_path / name,
+        safe_serialization=True,
+        max_shard_size=max_shard_size,
+    )
+
+
+def component_entry(library: str, class_name: str, repo: str, subfolder: str | None):
+    return [
+        None,
+        None,
+        {
+            "type_hint": [library, class_name],
+            "pretrained_model_name_or_path": repo,
+            "subfolder": subfolder,
+            "variant": None,
+            "revision": None,
+        },
+    ]
+
+
+def write_modular_index(output_path: Path, base_model: str, repo_id: str | None) -> None:
+    echo_repo = repo_id or str(output_path)
+    index = {
+        "_class_name": "EchoModularPipeline",
+        "_diffusers_version": __version__,
+        "_blocks_class_name": "EchoBlocks",
+        "text_encoder": component_entry("transformers", "Gemma3ForConditionalGeneration", base_model, None),
+        "tokenizer": component_entry("transformers", "GemmaTokenizerFast", base_model, None),
+        "connectors": component_entry("ltx2", "LTX2TextConnectors", echo_repo, "connectors"),
+        "vae": component_entry("diffusers", "AutoencoderKLLTX2Video", echo_repo, "vae"),
+        "audio_vae": component_entry("diffusers", "AutoencoderKLLTX2Audio", echo_repo, "audio_vae"),
+        "transformer": component_entry("diffusers", "LTX2VideoTransformer3DModel", echo_repo, "transformer"),
+        "vocoder": component_entry("ltx2", "LTX2VocoderWithBWE", echo_repo, "vocoder"),
+    }
+    (output_path / "modular_model_index.json").write_text(json.dumps(index, indent=2) + "\n", encoding="utf-8")
+
+
+def convert(
+    checkpoint: Path,
+    output_path: Path,
+    base_model: str,
+    repo_id: str | None,
+    max_shard_size: str,
+) -> None:
+    source = resolve_checkpoint(checkpoint)
+    output_path = output_path.expanduser().resolve()
+    output_path.mkdir(parents=True, exist_ok=True)
+
+    print(f"Loading Echo checkpoint from {source}", flush=True)
+    combined = load_file(str(source), device="cpu")
+    component_states = {
+        "dit": get_model_state_dict_from_combined_ckpt(combined, "model.diffusion_model"),
+        "vae": get_model_state_dict_from_combined_ckpt(combined, "vae"),
+        "audio_vae": get_model_state_dict_from_combined_ckpt(combined, "audio_vae"),
+        "vocoder": get_model_state_dict_from_combined_ckpt(combined, "vocoder"),
+    }
+    del combined
+    missing = [name for name, state in component_states.items() if not state]
+    if missing:
+        raise ValueError(f"Echo checkpoint is missing components: {missing}")
+
+    tensor_counts = {}
+    dit_state = component_states.pop("dit")
+    transformer = convert_ltx2_transformer(dict(dit_state), version="2.3")
+    tensor_counts["transformer"] = len(transformer.state_dict())
+    save_component(transformer, output_path, "transformer", max_shard_size)
+    del transformer
+    gc.collect()
+
+    connectors = convert_ltx2_connectors(dict(dit_state), version="2.3")
+    tensor_counts["connectors"] = len(connectors.state_dict())
+    save_component(connectors, output_path, "connectors", max_shard_size)
+    del connectors, dit_state
+    gc.collect()
+
+    vae = convert_ltx2_video_vae(component_states.pop("vae"), version="2.3", timestep_conditioning=False)
+    tensor_counts["vae"] = len(vae.state_dict())
+    save_component(vae, output_path, "vae", max_shard_size)
+    del vae
+    gc.collect()
+
+    audio_vae = convert_ltx2_audio_vae(component_states.pop("audio_vae"), version="2.3")
+    tensor_counts["audio_vae"] = len(audio_vae.state_dict())
+    save_component(audio_vae, output_path, "audio_vae", max_shard_size)
+    del audio_vae
+    gc.collect()
+
+    vocoder = convert_ltx2_vocoder(component_states.pop("vocoder"), version="2.3")
+    tensor_counts["vocoder"] = len(vocoder.state_dict())
+    save_component(vocoder, output_path, "vocoder", max_shard_size)
+    del vocoder
+    gc.collect()
+
+    write_modular_index(output_path, base_model=base_model, repo_id=repo_id)
+    report = {
+        "schema": "echo.diffusers.conversion.v1",
+        "source": str(source),
+        "precision": "bfloat16",
+        "tensor_counts": tensor_counts,
+        "base_model": base_model,
+        "model_repo": repo_id,
+        "vocoder_output_sample_rate": 48000,
+    }
+    (output_path / "conversion_report.json").write_text(json.dumps(report, indent=2) + "\n", encoding="utf-8")
+    print(f"Echo conversion complete: {output_path}", flush=True)
+
+
+def parse_args() -> argparse.Namespace:
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("--checkpoint", type=Path, required=True, help="Echo BF16 checkpoint or release folder.")
+    parser.add_argument("--output-path", type=Path, required=True, help="Destination Diffusers model directory.")
+    parser.add_argument(
+        "--base-model",
+        default="google/gemma-3-12b-it",
+        help="Gemma model repo/path containing the text encoder and tokenizer at its root.",
+    )
+    parser.add_argument(
+        "--repo-id",
+        default=None,
+        help="Future Hub repo id for the converted Echo components. Defaults to the local output path.",
+    )
+    parser.add_argument("--max-shard-size", default="5GB")
+    return parser.parse_args()
+
+
+if __name__ == "__main__":
+    args = parse_args()
+    convert(
+        checkpoint=args.checkpoint,
+        output_path=args.output_path,
+        base_model=args.base_model,
+        repo_id=args.repo_id,
+        max_shard_size=args.max_shard_size,
+    )

src/diffusers/__init__.py

@@ -517,6 +517,8 @@
             "Cosmos3DistilledModularPipeline",
             "Cosmos3OmniBlocks",
             "Cosmos3OmniModularPipeline",
+            "EchoBlocks",
+            "EchoModularPipeline",
             "ErnieImageAutoBlocks",
             "ErnieImageModularPipeline",
             "Flux2AutoBlocks",
@@ -1371,6 +1373,8 @@
             Cosmos3DistilledModularPipeline,
             Cosmos3OmniBlocks,
             Cosmos3OmniModularPipeline,
+            EchoBlocks,
+            EchoModularPipeline,
             ErnieImageAutoBlocks,
             ErnieImageModularPipeline,
             Flux2AutoBlocks,

src/diffusers/modular_pipelines/__init__.py

@@ -113,6 +113,10 @@
         "ErnieImageAutoBlocks",
         "ErnieImageModularPipeline",
     ]
+    _import_structure["echo"] = [
+        "EchoBlocks",
+        "EchoModularPipeline",
+    ]
     _import_structure["hunyuan_video1_5"] = [
         "HunyuanVideo15AutoBlocks",
         "HunyuanVideo15ModularPipeline",
@@ -156,6 +160,7 @@
             Cosmos3OmniBlocks,
             Cosmos3OmniModularPipeline,
         )
+        from .echo import EchoBlocks, EchoModularPipeline
         from .ernie_image import ErnieImageAutoBlocks, ErnieImageModularPipeline
         from .flux import FluxAutoBlocks, FluxKontextAutoBlocks, FluxKontextModularPipeline, FluxModularPipeline
         from .flux2 import (

src/diffusers/modular_pipelines/echo/__init__.py

@@ -0,0 +1,47 @@
+from typing import TYPE_CHECKING
+
+from ...utils import (
+    DIFFUSERS_SLOW_IMPORT,
+    OptionalDependencyNotAvailable,
+    _LazyModule,
+    get_objects_from_module,
+    is_torch_available,
+    is_transformers_available,
+)
+
+
+_dummy_objects = {}
+_import_structure = {}
+
+try:
+    if not (is_transformers_available() and is_torch_available()):
+        raise OptionalDependencyNotAvailable()
+except OptionalDependencyNotAvailable:
+    from ...utils import dummy_torch_and_transformers_objects  # noqa F403
+
+    _dummy_objects.update(get_objects_from_module(dummy_torch_and_transformers_objects))
+else:
+    _import_structure["modular_blocks_echo"] = ["EchoBlocks"]
+    _import_structure["modular_pipeline"] = ["EchoModularPipeline"]
+
+if TYPE_CHECKING or DIFFUSERS_SLOW_IMPORT:
+    try:
+        if not (is_transformers_available() and is_torch_available()):
+            raise OptionalDependencyNotAvailable()
+    except OptionalDependencyNotAvailable:
+        from ...utils.dummy_torch_and_transformers_objects import *  # noqa F403
+    else:
+        from .modular_blocks_echo import EchoBlocks
+        from .modular_pipeline import EchoModularPipeline
+else:
+    import sys
+
+    sys.modules[__name__] = _LazyModule(
+        __name__,
+        globals()["__file__"],
+        _import_structure,
+        module_spec=__spec__,
+    )
+
+    for name, value in _dummy_objects.items():
+        setattr(sys.modules[__name__], name, value)