Merge branch 'main' into feature/add-multitask-dit

CONTRIBUTING.md

@@ -14,7 +14,7 @@ You can contribute in many ways:
 - **Documentation:** Improve examples, guides, and docstrings.
 - **Feedback:** Submit tickets related to bugs or desired new features.
 
-If you are unsure where to start, join our [Discord Channel](https://discord.gg/JkrYNdmw).
+If you are unsure where to start, join our [Discord Channel](https://discord.gg/q8Dzzpym3f).
 
 ## Development Setup
 

docs/source/async.mdx

@@ -195,6 +195,7 @@ client_cfg = RobotClientConfig(
     robot=robot_cfg,
     server_address="localhost:8080",
     policy_device="mps",
+    client_device="cpu",
     policy_type="smolvla",
     pretrained_name_or_path="<user>/smolvla_async",
     chunk_size_threshold=0.5,

docs/source/using_dataset_tools.mdx

@@ -95,26 +95,26 @@ Convert an image-based dataset to video format, creating a new LeRobotDataset wh
 # Local-only: Save to a custom output directory (no hub push)
 lerobot-edit-dataset \
     --repo_id lerobot/pusht_image \
-    --operation.type convert_to_video \
+    --operation.type convert_image_to_video \
     --operation.output_dir /path/to/output/pusht_video
 
 # Save with new repo_id (local storage)
 lerobot-edit-dataset \
     --repo_id lerobot/pusht_image \
     --new_repo_id lerobot/pusht_video \
-    --operation.type convert_to_video
+    --operation.type convert_image_to_video
 
 # Convert and push to Hugging Face Hub
 lerobot-edit-dataset \
     --repo_id lerobot/pusht_image \
     --new_repo_id lerobot/pusht_video \
-    --operation.type convert_to_video \
+    --operation.type convert_image_to_video \
     --push_to_hub true
 
 # Convert with custom video codec and quality settings
 lerobot-edit-dataset \
     --repo_id lerobot/pusht_image \
-    --operation.type convert_to_video \
+    --operation.type convert_image_to_video \
     --operation.output_dir outputs/pusht_video \
     --operation.vcodec libsvtav1 \
     --operation.pix_fmt yuv420p \
@@ -124,16 +124,23 @@ lerobot-edit-dataset \
 # Convert only specific episodes
 lerobot-edit-dataset \
     --repo_id lerobot/pusht_image \
-    --operation.type convert_to_video \
+    --operation.type convert_image_to_video \
     --operation.output_dir outputs/pusht_video \
     --operation.episode_indices "[0, 1, 2, 5, 10]"
 
 # Convert with multiple workers for parallel processing
 lerobot-edit-dataset \
     --repo_id lerobot/pusht_image \
-    --operation.type convert_to_video \
+    --operation.type convert_image_to_video \
     --operation.output_dir outputs/pusht_video \
     --operation.num_workers 8
+
+# For memory-constrained systems, users can now specify limits:
+lerobot-edit-dataset \
+    --repo_id lerobot/pusht_image \
+    --operation.type convert_to_video \
+    --operation.max_episodes_per_batch 50 \
+    --operation.max_frames_per_batch 10000
 ```
 
 **Parameters:**

examples/tutorial/async-inf/robot_client.py

@@ -30,6 +30,7 @@ def main():
         robot=robot_cfg,
         server_address=server_address,
         policy_device="mps",
+        client_device="cpu",
         policy_type="act",
         pretrained_name_or_path="<user>/robot_learning_tutorial_act",
         chunk_size_threshold=0.5,  # g

src/lerobot/async_inference/configs.py

@@ -126,6 +126,12 @@ class RobotClientConfig:
 
     # Device configuration
     policy_device: str = field(default="cpu", metadata={"help": "Device for policy inference"})
+    client_device: str = field(
+        default="cpu",
+        metadata={
+            "help": "Device to move actions to after receiving from server (e.g., for downstream planners)"
+        },
+    )
 
     # Control behavior configuration
     chunk_size_threshold: float = field(default=0.5, metadata={"help": "Threshold for chunk size control"})
@@ -161,6 +167,9 @@ class RobotClientConfig:
         if not self.policy_device:
             raise ValueError("policy_device cannot be empty")
 
+        if not self.client_device:
+            raise ValueError("client_device cannot be empty")
+
         if self.chunk_size_threshold < 0 or self.chunk_size_threshold > 1:
             raise ValueError(f"chunk_size_threshold must be between 0 and 1, got {self.chunk_size_threshold}")
 
@@ -184,6 +193,7 @@ class RobotClientConfig:
             "policy_type": self.policy_type,
             "pretrained_name_or_path": self.pretrained_name_or_path,
             "policy_device": self.policy_device,
+            "client_device": self.client_device,
             "chunk_size_threshold": self.chunk_size_threshold,
             "fps": self.fps,
             "actions_per_chunk": self.actions_per_chunk,

src/lerobot/async_inference/constants.py

@@ -23,7 +23,7 @@ DEFAULT_INFERENCE_LATENCY = 1 / DEFAULT_FPS
 DEFAULT_OBS_QUEUE_TIMEOUT = 2
 
 # All action chunking policies
-SUPPORTED_POLICIES = ["act", "smolvla", "diffusion", "tdmpc", "vqbet", "pi0", "pi05"]
+SUPPORTED_POLICIES = ["act", "smolvla", "diffusion", "tdmpc", "vqbet", "pi0", "pi05", "groot"]
 
 # TODO: Add all other robots
 SUPPORTED_ROBOTS = ["so100_follower", "so101_follower", "bi_so_follower", "omx_follower"]

src/lerobot/async_inference/helpers.py

@@ -18,6 +18,7 @@ import os
 import time
 from dataclasses import dataclass, field
 from pathlib import Path
+from typing import Any
 
 import torch
 
@@ -39,8 +40,8 @@ from lerobot.utils.utils import init_logging
 
 Action = torch.Tensor
 
-# observation as received from the robot
+# observation as received from the robot (can be numpy arrays, floats, etc.)
-RawObservation = dict[str, torch.Tensor]
+RawObservation = dict[str, Any]
 
 # observation as those recorded in LeRobot dataset (keys are different)
 LeRobotObservation = dict[str, torch.Tensor]

src/lerobot/async_inference/policy_server.py

@@ -381,6 +381,8 @@ class PolicyServer(services_pb2_grpc.AsyncInferenceServicer):
         action_tensor = torch.stack(processed_actions, dim=1).squeeze(0)
         self.logger.debug(f"Postprocessed action shape: {action_tensor.shape}")
 
+        action_tensor = action_tensor.detach().cpu()
+
         """5. Convert to TimedAction list"""
         action_chunk = self._time_action_chunk(
             observation_t.get_timestamp(), list(action_tensor), observation_t.get_timestep()

src/lerobot/async_inference/robot_client.py

@@ -25,6 +25,7 @@ python src/lerobot/async_inference/robot_client.py \
     --policy_type=act \
     --pretrained_name_or_path=user/model \
     --policy_device=mps \
+    --client_device=cpu \
     --actions_per_chunk=50 \
     --chunk_size_threshold=0.5 \
     --aggregate_fn_name=weighted_average \
@@ -40,6 +41,7 @@ from collections.abc import Callable
 from dataclasses import asdict
 from pprint import pformat
 from queue import Queue
+from typing import Any
 
 import draccus
 import grpc
@@ -47,7 +49,6 @@ import torch
 
 from lerobot.cameras.opencv.configuration_opencv import OpenCVCameraConfig  # noqa: F401
 from lerobot.cameras.realsense.configuration_realsense import RealSenseCameraConfig  # noqa: F401
-from lerobot.processor import RobotAction
 from lerobot.robots import (  # noqa: F401
     Robot,
     RobotConfig,
@@ -285,6 +286,21 @@ class RobotClient:
                 timed_actions = pickle.loads(actions_chunk.data)  # nosec
                 deserialize_time = time.perf_counter() - deserialize_start
 
+                # Log device type of received actions
+                if len(timed_actions) > 0:
+                    received_device = timed_actions[0].get_action().device.type
+                    self.logger.debug(f"Received actions on device: {received_device}")
+
+                # Move actions to client_device (e.g., for downstream planners that need GPU)
+                client_device = self.config.client_device
+                if client_device != "cpu":
+                    for timed_action in timed_actions:
+                        if timed_action.get_action().device.type != client_device:
+                            timed_action.action = timed_action.get_action().to(client_device)
+                    self.logger.debug(f"Converted actions to device: {client_device}")
+                else:
+                    self.logger.debug(f"Actions kept on device: {client_device}")
+
                 self.action_chunk_size = max(self.action_chunk_size, len(timed_actions))
 
                 # Calculate network latency if we have matching observations
@@ -351,7 +367,7 @@ class RobotClient:
         action = {key: action_tensor[i].item() for i, key in enumerate(self.robot.action_features)}
         return action
 
-    def control_loop_action(self, verbose: bool = False) -> RobotAction:
+    def control_loop_action(self, verbose: bool = False) -> dict[str, Any]:
         """Reading and performing actions in local queue"""
 
         # Lock only for queue operations

src/lerobot/datasets/aggregate.py

@@ -19,6 +19,7 @@ import logging
 import shutil
 from pathlib import Path
 
+import datasets
 import pandas as pd
 import tqdm
 
@@ -32,6 +33,7 @@ from lerobot.datasets.utils import (
     DEFAULT_VIDEO_FILE_SIZE_IN_MB,
     DEFAULT_VIDEO_PATH,
     get_file_size_in_mb,
+    get_hf_features_from_features,
     get_parquet_file_size_in_mb,
     to_parquet_with_hf_images,
     update_chunk_file_indices,
@@ -402,12 +404,21 @@ def aggregate_data(src_meta, dst_meta, data_idx, data_files_size_in_mb, chunk_si
     }
 
     unique_chunk_file_ids = sorted(unique_chunk_file_ids)
+    contains_images = len(dst_meta.image_keys) > 0
+
+    # retrieve features schema for proper image typing in parquet
+    hf_features = get_hf_features_from_features(dst_meta.features) if contains_images else None
 
     for src_chunk_idx, src_file_idx in unique_chunk_file_ids:
         src_path = src_meta.root / DEFAULT_DATA_PATH.format(
             chunk_index=src_chunk_idx, file_index=src_file_idx
         )
-        df = pd.read_parquet(src_path)
+        if contains_images:
+            # Use HuggingFace datasets to read source data to preserve image format
+            src_ds = datasets.Dataset.from_parquet(str(src_path))
+            df = src_ds.to_pandas()
+        else:
+            df = pd.read_parquet(src_path)
         df = update_data_df(df, src_meta, dst_meta)
 
         data_idx = append_or_create_parquet_file(
@@ -417,8 +428,9 @@ def aggregate_data(src_meta, dst_meta, data_idx, data_files_size_in_mb, chunk_si
             data_files_size_in_mb,
             chunk_size,
             DEFAULT_DATA_PATH,
-            contains_images=len(dst_meta.image_keys) > 0,
+            contains_images=contains_images,
             aggr_root=dst_meta.root,
+            hf_features=hf_features,
         )
 
     return data_idx
@@ -488,6 +500,7 @@ def append_or_create_parquet_file(
     default_path: str,
     contains_images: bool = False,
     aggr_root: Path = None,
+    hf_features: datasets.Features | None = None,
 ):
     """Appends data to an existing parquet file or creates a new one based on size constraints.
 
@@ -503,6 +516,7 @@ def append_or_create_parquet_file(
         default_path: Format string for generating file paths.
         contains_images: Whether the data contains images requiring special handling.
         aggr_root: Root path for the aggregated dataset.
+        hf_features: Optional HuggingFace Features schema for proper image typing.
 
     Returns:
         dict: Updated index dictionary with current chunk and file indices.
@@ -512,7 +526,7 @@ def append_or_create_parquet_file(
     if not dst_path.exists():
         dst_path.parent.mkdir(parents=True, exist_ok=True)
         if contains_images:
-            to_parquet_with_hf_images(df, dst_path)
+            to_parquet_with_hf_images(df, dst_path, features=hf_features)
         else:
             df.to_parquet(dst_path)
         return idx
@@ -527,12 +541,17 @@ def append_or_create_parquet_file(
         final_df = df
         target_path = new_path
     else:
-        existing_df = pd.read_parquet(dst_path)
+        if contains_images:
+            # Use HuggingFace datasets to read existing data to preserve image format
+            existing_ds = datasets.Dataset.from_parquet(str(dst_path))
+            existing_df = existing_ds.to_pandas()
+        else:
+            existing_df = pd.read_parquet(dst_path)
         final_df = pd.concat([existing_df, df], ignore_index=True)
         target_path = dst_path
 
     if contains_images:
-        to_parquet_with_hf_images(final_df, target_path)
+        to_parquet_with_hf_images(final_df, target_path, features=hf_features)
     else:
         final_df.to_parquet(target_path)
 

src/lerobot/datasets/dataset_tools.py

@@ -26,6 +26,7 @@ This module provides utilities for:
 import logging
 import shutil
 from collections.abc import Callable
+from concurrent.futures import ThreadPoolExecutor, as_completed
 from pathlib import Path
 
 import datasets
@@ -51,7 +52,8 @@ from lerobot.datasets.utils import (
     write_stats,
     write_tasks,
 )
-from lerobot.utils.constants import HF_LEROBOT_HOME
+from lerobot.datasets.video_utils import encode_video_frames, get_video_info
+from lerobot.utils.constants import HF_LEROBOT_HOME, OBS_IMAGE
 
 
 def _load_episode_with_stats(src_dataset: LeRobotDataset, episode_idx: int) -> dict:
@@ -1083,3 +1085,561 @@ def _copy_episodes_metadata_and_stats(
     else:
         if src_dataset.meta.stats:
             write_stats(src_dataset.meta.stats, dst_meta.root)
+
+
+def _save_episode_images_for_video(
+    dataset: LeRobotDataset,
+    imgs_dir: Path,
+    img_key: str,
+    episode_index: int,
+    num_workers: int = 4,
+) -> None:
+    """Save images from a specific episode and camera to disk for video encoding.
+
+    Args:
+        dataset: The LeRobot dataset to extract images from
+        imgs_dir: Directory to save images to
+        img_key: The image key (camera) to extract
+        episode_index: Index of the episode to save
+        num_workers: Number of threads for parallel image saving
+    """
+    # Create directory
+    imgs_dir.mkdir(parents=True, exist_ok=True)
+
+    # Get dataset without torch format for PIL image access
+    hf_dataset = dataset.hf_dataset.with_format(None)
+
+    # Select only this camera's images
+    imgs_dataset = hf_dataset.select_columns(img_key)
+
+    # Get episode start and end indices
+    from_idx = dataset.meta.episodes["dataset_from_index"][episode_index]
+    to_idx = dataset.meta.episodes["dataset_to_index"][episode_index]
+
+    # Get all items for this episode
+    episode_dataset = imgs_dataset.select(range(from_idx, to_idx))
+
+    # Define function to save a single image
+    def save_single_image(i_item_tuple):
+        i, item = i_item_tuple
+        img = item[img_key]
+        # Use frame-XXXXXX.png format to match encode_video_frames expectations
+        img.save(str(imgs_dir / f"frame-{i:06d}.png"), quality=100)
+        return i
+
+    # Save images with proper naming convention for encode_video_frames (frame-XXXXXX.png)
+    items = list(enumerate(episode_dataset))
+
+    with ThreadPoolExecutor(max_workers=num_workers) as executor:
+        futures = [executor.submit(save_single_image, item) for item in items]
+        for future in as_completed(futures):
+            future.result()  # This will raise any exceptions that occurred
+
+
+def _save_batch_episodes_images(
+    dataset: LeRobotDataset,
+    imgs_dir: Path,
+    img_key: str,
+    episode_indices: list[int],
+    num_workers: int = 4,
+) -> list[float]:
+    """Save images from multiple episodes to disk for batch video encoding.
+
+    Args:
+        dataset: The LeRobot dataset to extract images from
+        imgs_dir: Directory to save images to
+        img_key: The image key (camera) to extract
+        episode_indices: List of episode indices to save
+        num_workers: Number of threads for parallel image saving
+
+    Returns:
+        List of episode durations in seconds
+    """
+    imgs_dir.mkdir(parents=True, exist_ok=True)
+    hf_dataset = dataset.hf_dataset.with_format(None)
+    imgs_dataset = hf_dataset.select_columns(img_key)
+
+    # Define function to save a single image with global frame index
+    # Defined once outside the loop to avoid repeated closure creation
+    def save_single_image(i_item_tuple, base_frame_idx, img_key_param):
+        i, item = i_item_tuple
+        img = item[img_key_param]
+        # Use global frame index for naming
+        img.save(str(imgs_dir / f"frame-{base_frame_idx + i:06d}.png"), quality=100)
+        return i
+
+    episode_durations = []
+    frame_idx = 0
+
+    for ep_idx in episode_indices:
+        # Get episode range
+        from_idx = dataset.meta.episodes["dataset_from_index"][ep_idx]
+        to_idx = dataset.meta.episodes["dataset_to_index"][ep_idx]
+        episode_length = to_idx - from_idx
+        episode_durations.append(episode_length / dataset.fps)
+
+        # Get episode images
+        episode_dataset = imgs_dataset.select(range(from_idx, to_idx))
+
+        # Save images
+        items = list(enumerate(episode_dataset))
+        with ThreadPoolExecutor(max_workers=num_workers) as executor:
+            futures = [executor.submit(save_single_image, item, frame_idx, img_key) for item in items]
+            for future in as_completed(futures):
+                future.result()
+
+        frame_idx += episode_length
+
+    return episode_durations
+
+
+def _iter_episode_batches(
+    episode_indices: list[int],
+    episode_lengths: dict[int, int],
+    size_per_frame_mb: float,
+    video_file_size_limit: float,
+    max_episodes: int | None,
+    max_frames: int | None,
+):
+    """Generator that yields batches of episode indices for video encoding.
+
+    Groups episodes into batches that respect size and memory constraints:
+    - Stays under video file size limit
+    - Respects maximum episodes per batch (if specified)
+    - Respects maximum frames per batch (if specified)
+
+    Args:
+        episode_indices: List of episode indices to batch
+        episode_lengths: Dictionary mapping episode index to episode length
+        size_per_frame_mb: Estimated size per frame in MB
+        video_file_size_limit: Maximum video file size in MB
+        max_episodes: Maximum number of episodes per batch (None = no limit)
+        max_frames: Maximum number of frames per batch (None = no limit)
+
+    Yields:
+        List of episode indices for each batch
+    """
+    batch_episodes = []
+    estimated_size = 0.0
+    total_frames = 0
+
+    for ep_idx in episode_indices:
+        ep_length = episode_lengths[ep_idx]
+        ep_estimated_size = ep_length * size_per_frame_mb
+
+        # we check if adding this episode would exceed any constraint
+        would_exceed_size = estimated_size > 0 and estimated_size + ep_estimated_size >= video_file_size_limit
+        would_exceed_episodes = max_episodes is not None and len(batch_episodes) >= max_episodes
+        would_exceed_frames = max_frames is not None and total_frames + ep_length > max_frames
+
+        if batch_episodes and (would_exceed_size or would_exceed_episodes or would_exceed_frames):
+            # yield current batch before adding this episode
+            yield batch_episodes
+            # start a new batch with current episode
+            batch_episodes = [ep_idx]
+            estimated_size = ep_estimated_size
+            total_frames = ep_length
+        else:
+            # add to current batch
+            batch_episodes.append(ep_idx)
+            estimated_size += ep_estimated_size
+            total_frames += ep_length
+
+    # yield final batch if not empty
+    if batch_episodes:
+        yield batch_episodes
+
+
+def _estimate_frame_size_via_calibration(
+    dataset: LeRobotDataset,
+    img_key: str,
+    episode_indices: list[int],
+    temp_dir: Path,
+    fps: int,
+    vcodec: str,
+    pix_fmt: str,
+    g: int,
+    crf: int,
+    fast_decode: int,
+    num_calibration_frames: int = 30,
+) -> float:
+    """Estimate MB per frame by encoding a small calibration sample.
+
+    Encodes a representative sample of frames using the exact codec parameters
+    to measure actual compression ratio, which is more accurate than heuristics.
+
+    Args:
+        dataset: Source dataset with images.
+        img_key: Image key to calibrate (e.g., "observation.images.top").
+        episode_indices: List of episode indices being processed.
+        temp_dir: Temporary directory for calibration files.
+        fps: Frames per second for video encoding.
+        vcodec: Video codec (libsvtav1, h264, hevc).
+        pix_fmt: Pixel format (yuv420p, etc.).
+        g: GOP size (group of pictures).
+        crf: Constant Rate Factor (quality).
+        fast_decode: Fast decode tuning parameter.
+        num_calibration_frames: Number of frames to use for calibration (default: 30).
+
+    Returns:
+        Estimated size in MB per frame based on actual encoding.
+    """
+    calibration_dir = temp_dir / "calibration" / img_key
+    calibration_dir.mkdir(parents=True, exist_ok=True)
+
+    try:
+        # Select a representative episode (prefer middle episode if available)
+        calibration_ep_idx = episode_indices[len(episode_indices) // 2]
+
+        # Get episode range
+        from_idx = dataset.meta.episodes["dataset_from_index"][calibration_ep_idx]
+        to_idx = dataset.meta.episodes["dataset_to_index"][calibration_ep_idx]
+        episode_length = to_idx - from_idx
+
+        # Use up to num_calibration_frames from this episode
+        num_frames = min(num_calibration_frames, episode_length)
+
+        # Get frames from dataset
+        hf_dataset = dataset.hf_dataset.with_format(None)
+        sample_indices = range(from_idx, from_idx + num_frames)
+
+        # Save calibration frames
+        for i, idx in enumerate(sample_indices):
+            img = hf_dataset[idx][img_key]
+            img.save(str(calibration_dir / f"frame-{i:06d}.png"), quality=100)
+
+        # Encode calibration video
+        calibration_video_path = calibration_dir / "calibration.mp4"
+        encode_video_frames(
+            imgs_dir=calibration_dir,
+            video_path=calibration_video_path,
+            fps=fps,
+            vcodec=vcodec,
+            pix_fmt=pix_fmt,
+            g=g,
+            crf=crf,
+            fast_decode=fast_decode,
+            overwrite=True,
+        )
+
+        # Measure actual compressed size
+        video_size_bytes = calibration_video_path.stat().st_size
+        video_size_mb = video_size_bytes / BYTES_PER_MIB
+        size_per_frame_mb = video_size_mb / num_frames
+
+        logging.info(
+            f"  Calibration: {num_frames} frames -> {video_size_mb:.2f} MB "
+            f"= {size_per_frame_mb:.4f} MB/frame for {img_key}"
+        )
+
+        return size_per_frame_mb
+
+    finally:
+        # Clean up calibration files
+        if calibration_dir.exists():
+            shutil.rmtree(calibration_dir)
+
+
+def _copy_data_without_images(
+    src_dataset: LeRobotDataset,
+    dst_meta: LeRobotDatasetMetadata,
+    episode_indices: list[int],
+    img_keys: list[str],
+) -> None:
+    """Copy data files without image columns.
+
+    Args:
+        src_dataset: Source dataset
+        dst_meta: Destination metadata
+        episode_indices: Episodes to include
+        img_keys: Image keys to remove
+    """
+    from lerobot.datasets.utils import DATA_DIR
+
+    data_dir = src_dataset.root / DATA_DIR
+    parquet_files = sorted(data_dir.glob("*/*.parquet"))
+
+    if not parquet_files:
+        raise ValueError(f"No parquet files found in {data_dir}")
+
+    episode_set = set(episode_indices)
+
+    for src_path in tqdm(parquet_files, desc="Processing data files"):
+        df = pd.read_parquet(src_path).reset_index(drop=True)
+
+        # Filter to only include selected episodes
+        df = df[df["episode_index"].isin(episode_set)].copy()
+
+        if len(df) == 0:
+            continue
+
+        # Remove image columns
+        columns_to_drop = [col for col in img_keys if col in df.columns]
+        if columns_to_drop:
+            df = df.drop(columns=columns_to_drop)
+
+        # Get chunk and file indices from path
+        relative_path = src_path.relative_to(src_dataset.root)
+        chunk_dir = relative_path.parts[1]
+        file_name = relative_path.parts[2]
+        chunk_idx = int(chunk_dir.split("-")[1])
+        file_idx = int(file_name.split("-")[1].split(".")[0])
+
+        # Write to destination without pandas index
+        dst_path = dst_meta.root / f"data/chunk-{chunk_idx:03d}/file-{file_idx:03d}.parquet"
+        dst_path.parent.mkdir(parents=True, exist_ok=True)
+        df.to_parquet(dst_path, index=False)
+
+
+# Video conversion constants
+BYTES_PER_KIB = 1024
+BYTES_PER_MIB = BYTES_PER_KIB * BYTES_PER_KIB
+
+
+def convert_image_to_video_dataset(
+    dataset: LeRobotDataset,
+    output_dir: Path,
+    repo_id: str | None = None,
+    vcodec: str = "libsvtav1",
+    pix_fmt: str = "yuv420p",
+    g: int = 2,
+    crf: int = 30,
+    fast_decode: int = 0,
+    episode_indices: list[int] | None = None,
+    num_workers: int = 4,
+    max_episodes_per_batch: int | None = None,
+    max_frames_per_batch: int | None = None,
+) -> LeRobotDataset:
+    """Convert image-to-video dataset.
+
+    Creates a new LeRobotDataset with images encoded as videos, following the proper
+    LeRobot dataset structure with videos stored in chunked MP4 files.
+
+    Args:
+        dataset: The source LeRobot dataset with images
+        output_dir: Directory to save the new video dataset
+        repo_id: Repository ID for the new dataset (default: original_id + "_video")
+        vcodec: Video codec (default: libsvtav1)
+        pix_fmt: Pixel format (default: yuv420p)
+        g: Group of pictures size (default: 2)
+        crf: Constant rate factor (default: 30)
+        fast_decode: Fast decode tuning (default: 0)
+        episode_indices: List of episode indices to convert (None = all episodes)
+        num_workers: Number of threads for parallel processing (default: 4)
+        max_episodes_per_batch: Maximum episodes per video batch to avoid memory issues (None = no limit)
+        max_frames_per_batch: Maximum frames per video batch to avoid memory issues (None = no limit)
+
+    Returns:
+        New LeRobotDataset with images encoded as videos
+    """
+    # Check that it's an image dataset
+    if len(dataset.meta.video_keys) > 0:
+        raise ValueError(
+            f"This operation is for image datasets only. Video dataset provided: {dataset.repo_id}"
+        )
+
+    # Get all image keys
+    hf_dataset = dataset.hf_dataset.with_format(None)
+    img_keys = [key for key in hf_dataset.features if key.startswith(OBS_IMAGE)]
+
+    if len(img_keys) == 0:
+        raise ValueError(f"No image keys found in dataset {dataset.repo_id}")
+
+    # Determine which episodes to process
+    if episode_indices is None:
+        episode_indices = list(range(dataset.meta.total_episodes))
+
+    if repo_id is None:
+        repo_id = f"{dataset.repo_id}_video"
+
+    logging.info(
+        f"Converting {len(episode_indices)} episodes with {len(img_keys)} cameras from {dataset.repo_id}"
+    )
+    logging.info(f"Video codec: {vcodec}, pixel format: {pix_fmt}, GOP: {g}, CRF: {crf}")
+
+    # Create new features dict, converting image features to video features
+    new_features = {}
+    for key, value in dataset.meta.features.items():
+        if key not in img_keys:
+            new_features[key] = value
+        else:
+            # Convert image key to video format
+            new_features[key] = value.copy()
+            new_features[key]["dtype"] = "video"  # Change dtype from "image" to "video"
+            # Video info will be updated after episodes are encoded
+
+    # Create new metadata for video dataset
+    new_meta = LeRobotDatasetMetadata.create(
+        repo_id=repo_id,
+        fps=dataset.meta.fps,
+        features=new_features,
+        robot_type=dataset.meta.robot_type,
+        root=output_dir,
+        use_videos=True,
+        chunks_size=dataset.meta.chunks_size,
+        data_files_size_in_mb=dataset.meta.data_files_size_in_mb,
+        video_files_size_in_mb=dataset.meta.video_files_size_in_mb,
+    )
+
+    # Create temporary directory for image extraction
+    temp_dir = output_dir / "temp_images"
+    temp_dir.mkdir(parents=True, exist_ok=True)
+
+    # Process all episodes and batch encode videos
+    # Use dictionary for O(1) episode metadata lookups instead of O(n) linear search
+    all_episode_metadata = {}
+    fps = int(dataset.fps)
+
+    try:
+        # Build episode metadata entries first
+        logging.info("Building episode metadata...")
+        cumulative_frame_idx = 0
+        for ep_idx in episode_indices:
+            src_episode = dataset.meta.episodes[ep_idx]
+            ep_length = src_episode["length"]
+            ep_meta = {
+                "episode_index": ep_idx,
+                "length": ep_length,
+                "dataset_from_index": cumulative_frame_idx,
+                "dataset_to_index": cumulative_frame_idx + ep_length,
+            }
+            if "data/chunk_index" in src_episode:
+                ep_meta["data/chunk_index"] = src_episode["data/chunk_index"]
+                ep_meta["data/file_index"] = src_episode["data/file_index"]
+            all_episode_metadata[ep_idx] = ep_meta
+            cumulative_frame_idx += ep_length
+
+        # Process each camera and batch encode multiple episodes together
+        video_file_size_limit = new_meta.video_files_size_in_mb
+
+        # Pre-compute episode lengths for batching
+        episode_lengths = {ep_idx: dataset.meta.episodes["length"][ep_idx] for ep_idx in episode_indices}
+
+        for img_key in tqdm(img_keys, desc="Processing cameras"):
+            # Estimate size per frame by encoding a small calibration sample
+            # This provides accurate compression ratio for the specific codec parameters
+            size_per_frame_mb = _estimate_frame_size_via_calibration(
+                dataset=dataset,
+                img_key=img_key,
+                episode_indices=episode_indices,
+                temp_dir=temp_dir,
+                fps=fps,
+                vcodec=vcodec,
+                pix_fmt=pix_fmt,
+                g=g,
+                crf=crf,
+                fast_decode=fast_decode,
+            )
+
+            logging.info(f"Processing camera: {img_key}")
+            chunk_idx, file_idx = 0, 0
+            cumulative_timestamp = 0.0
+
+            # Process episodes in batches to stay under size limit
+            for batch_episodes in _iter_episode_batches(
+                episode_indices=episode_indices,
+                episode_lengths=episode_lengths,
+                size_per_frame_mb=size_per_frame_mb,
+                video_file_size_limit=video_file_size_limit,
+                max_episodes=max_episodes_per_batch,
+                max_frames=max_frames_per_batch,
+            ):
+                total_frames_in_batch = sum(episode_lengths[idx] for idx in batch_episodes)
+                logging.info(
+                    f"  Encoding batch of {len(batch_episodes)} episodes "
+                    f"({batch_episodes[0]}-{batch_episodes[-1]}) = {total_frames_in_batch} frames"
+                )
+
+                # Save images for all episodes in this batch
+                imgs_dir = temp_dir / f"batch_{chunk_idx}_{file_idx}" / img_key
+                episode_durations = _save_batch_episodes_images(
+                    dataset=dataset,
+                    imgs_dir=imgs_dir,
+                    img_key=img_key,
+                    episode_indices=batch_episodes,
+                    num_workers=num_workers,
+                )
+
+                # Encode all batched episodes into single video
+                video_path = new_meta.root / new_meta.video_path.format(
+                    video_key=img_key, chunk_index=chunk_idx, file_index=file_idx
+                )
+                video_path.parent.mkdir(parents=True, exist_ok=True)
+
+                encode_video_frames(
+                    imgs_dir=imgs_dir,
+                    video_path=video_path,
+                    fps=fps,
+                    vcodec=vcodec,
+                    pix_fmt=pix_fmt,
+                    g=g,
+                    crf=crf,
+                    fast_decode=fast_decode,
+                    overwrite=True,
+                )
+
+                # Clean up temporary images
+                shutil.rmtree(imgs_dir)
+
+                # Update metadata for each episode in the batch
+                for ep_idx, duration in zip(batch_episodes, episode_durations, strict=True):
+                    from_timestamp = cumulative_timestamp
+                    to_timestamp = cumulative_timestamp + duration
+                    cumulative_timestamp = to_timestamp
+
+                    # Find episode metadata entry and add video metadata (O(1) dictionary lookup)
+                    ep_meta = all_episode_metadata[ep_idx]
+                    ep_meta[f"videos/{img_key}/chunk_index"] = chunk_idx
+                    ep_meta[f"videos/{img_key}/file_index"] = file_idx
+                    ep_meta[f"videos/{img_key}/from_timestamp"] = from_timestamp
+                    ep_meta[f"videos/{img_key}/to_timestamp"] = to_timestamp
+
+                # Move to next video file for next batch
+                chunk_idx, file_idx = update_chunk_file_indices(chunk_idx, file_idx, new_meta.chunks_size)
+                cumulative_timestamp = 0.0
+
+        # Copy and transform data files (removing image columns)
+        _copy_data_without_images(dataset, new_meta, episode_indices, img_keys)
+
+        # Save episode metadata
+        episodes_df = pd.DataFrame(list(all_episode_metadata.values()))
+        episodes_path = new_meta.root / "meta" / "episodes" / "chunk-000" / "file-000.parquet"
+        episodes_path.parent.mkdir(parents=True, exist_ok=True)
+        episodes_df.to_parquet(episodes_path, index=False)
+
+        # Update metadata info
+        new_meta.info["total_episodes"] = len(episode_indices)
+        new_meta.info["total_frames"] = sum(ep["length"] for ep in all_episode_metadata.values())
+        new_meta.info["total_tasks"] = dataset.meta.total_tasks
+        new_meta.info["splits"] = {"train": f"0:{len(episode_indices)}"}
+
+        # Update video info for all image keys (now videos)
+        # We need to manually set video info since update_video_info() checks video_keys first
+        for img_key in img_keys:
+            if not new_meta.features[img_key].get("info", None):
+                video_path = new_meta.root / new_meta.video_path.format(
+                    video_key=img_key, chunk_index=0, file_index=0
+                )
+                new_meta.info["features"][img_key]["info"] = get_video_info(video_path)
+
+        write_info(new_meta.info, new_meta.root)
+
+        # Copy stats and tasks
+        if dataset.meta.stats is not None:
+            # Remove image stats
+            new_stats = {k: v for k, v in dataset.meta.stats.items() if k not in img_keys}
+            write_stats(new_stats, new_meta.root)
+
+        if dataset.meta.tasks is not None:
+            write_tasks(dataset.meta.tasks, new_meta.root)
+
+    finally:
+        # Clean up temporary directory
+        if temp_dir.exists():
+            shutil.rmtree(temp_dir)
+
+    logging.info(f"Completed converting {dataset.repo_id} to video format")
+    logging.info(f"New dataset saved to: {output_dir}")
+
+    # Return new dataset
+    return LeRobotDataset(repo_id=repo_id, root=output_dir)

src/lerobot/datasets/utils.py

@@ -1172,12 +1172,21 @@ def validate_episode_buffer(episode_buffer: dict, total_episodes: int, features:
         )
 
 
-def to_parquet_with_hf_images(df: pandas.DataFrame, path: Path) -> None:
+def to_parquet_with_hf_images(
+    df: pandas.DataFrame, path: Path, features: datasets.Features | None = None
+) -> None:
     """This function correctly writes to parquet a panda DataFrame that contains images encoded by HF dataset.
     This way, it can be loaded by HF dataset and correctly formatted images are returned.
+
+    Args:
+        df: DataFrame to write to parquet.
+        path: Path to write the parquet file.
+        features: Optional HuggingFace Features schema. If provided, ensures image columns
+                  are properly typed as Image() in the parquet schema.
     """
     # TODO(qlhoest): replace this weird synthax by `df.to_parquet(path)` only
-    datasets.Dataset.from_dict(df.to_dict(orient="list")).to_parquet(path)
+    ds = datasets.Dataset.from_dict(df.to_dict(orient="list"), features=features)
+    ds.to_parquet(path)
 
 
 def item_to_torch(item: dict) -> dict:

src/lerobot/motors/feetech/tables.py

@@ -205,6 +205,7 @@ MODEL_BAUDRATE_TABLE = {
 
 # Sign-Magnitude encoding bits
 STS_SMS_SERIES_ENCODINGS_TABLE = {
+    "Present_Load": 10,
     "Homing_Offset": 11,
     "Goal_Position": 15,
     "Goal_Velocity": 15,

src/lerobot/policies/groot/modeling_groot.py

@@ -32,16 +32,22 @@ Notes:
   from LeRobot, see `GrootPolicy.finetune_with_groot_runner` below.
 """
 
+import builtins
 import os
 from collections import deque
+from pathlib import Path
+from typing import TypeVar
 
 import torch
 from torch import Tensor
 
+from lerobot.configs.types import FeatureType, PolicyFeature
 from lerobot.policies.groot.configuration_groot import GrootConfig
 from lerobot.policies.groot.groot_n1 import GR00TN15
 from lerobot.policies.pretrained import PreTrainedPolicy
-from lerobot.utils.constants import ACTION
+from lerobot.utils.constants import ACTION, OBS_IMAGES
+
+T = TypeVar("T", bound="GrootPolicy")
 
 
 class GrootPolicy(PreTrainedPolicy):
@@ -90,6 +96,129 @@ class GrootPolicy(PreTrainedPolicy):
         """Reset policy state when environment resets."""
         self._action_queue = deque([], maxlen=self.config.n_action_steps)
 
+    @classmethod
+    def from_pretrained(
+        cls: builtins.type[T],
+        pretrained_name_or_path: str | Path,
+        *,
+        config: GrootConfig | None = None,
+        force_download: bool = False,
+        resume_download: bool | None = None,
+        proxies: dict | None = None,
+        token: str | bool | None = None,
+        cache_dir: str | Path | None = None,
+        local_files_only: bool = False,
+        revision: str | None = None,
+        strict: bool = True,
+        **kwargs,
+    ) -> T:
+        """Load Groot policy from pretrained model.
+
+        Handles two cases:
+        1. Base GR00T models (e.g., 'nvidia/GR00T-N1.5-3B') - loads the raw model
+        2. Fine-tuned LeRobot checkpoints - loads config and weights from safetensors
+
+        Args:
+            pretrained_name_or_path: Path to the GR00T model or fine-tuned checkpoint
+            config: Optional GrootConfig. If None, loads from checkpoint or creates default
+            force_download: Force download even if cached
+            resume_download: Resume interrupted download
+            proxies: Proxy settings
+            token: HuggingFace authentication token
+            cache_dir: Cache directory path
+            local_files_only: Only use local files
+            revision: Specific model revision
+            strict: Strict state dict loading
+            **kwargs: Additional arguments (passed to config)
+
+        Returns:
+            Initialized GrootPolicy instance with loaded model
+        """
+        from huggingface_hub import hf_hub_download
+        from huggingface_hub.constants import SAFETENSORS_SINGLE_FILE
+        from huggingface_hub.errors import HfHubHTTPError
+
+        print(
+            "The Groot policy is a wrapper around Nvidia's GR00T N1.5 model.\n"
+            f"Loading pretrained model from: {pretrained_name_or_path}"
+        )
+
+        model_id = str(pretrained_name_or_path)
+        is_finetuned_checkpoint = False
+
+        # Check if this is a fine-tuned LeRobot checkpoint (has model.safetensors)
+        try:
+            if os.path.isdir(model_id):
+                is_finetuned_checkpoint = os.path.exists(os.path.join(model_id, SAFETENSORS_SINGLE_FILE))
+            else:
+                # Try to download the safetensors file to check if it exists
+                try:
+                    hf_hub_download(
+                        repo_id=model_id,
+                        filename=SAFETENSORS_SINGLE_FILE,
+                        revision=revision,
+                        cache_dir=cache_dir,
+                        force_download=False,  # Just check, don't force download
+                        proxies=proxies,
+                        token=token,
+                        local_files_only=local_files_only,
+                    )
+                    is_finetuned_checkpoint = True
+                except HfHubHTTPError:
+                    is_finetuned_checkpoint = False
+        except Exception:
+            is_finetuned_checkpoint = False
+
+        if is_finetuned_checkpoint:
+            # This is a fine-tuned LeRobot checkpoint - use parent class loading
+            print("Detected fine-tuned LeRobot checkpoint, loading with state dict...")
+            return super().from_pretrained(
+                pretrained_name_or_path=pretrained_name_or_path,
+                config=config,
+                force_download=force_download,
+                resume_download=resume_download,
+                proxies=proxies,
+                token=token,
+                cache_dir=cache_dir,
+                local_files_only=local_files_only,
+                revision=revision,
+                strict=strict,
+                **kwargs,
+            )
+
+        # This is a base GR00T model - load it fresh
+        print("Detected base GR00T model, loading from HuggingFace...")
+
+        if config is None:
+            # Create default config with the pretrained path
+            config = GrootConfig(base_model_path=str(pretrained_name_or_path))
+
+            # Add minimal visual feature required for validation
+            # validate_features() will automatically add state and action features
+            # These are placeholders - actual robot features come from the preprocessor
+            if not config.input_features:
+                config.input_features = {
+                    f"{OBS_IMAGES}.camera": PolicyFeature(
+                        type=FeatureType.VISUAL,
+                        shape=(3, 224, 224),  # Default image size from config
+                    ),
+                }
+        else:
+            # Override the base_model_path with the provided path
+            config.base_model_path = str(pretrained_name_or_path)
+
+        # Pass through any additional config overrides from kwargs
+        for key, value in kwargs.items():
+            if hasattr(config, key):
+                setattr(config, key, value)
+
+        # Create a fresh policy instance - this will automatically load the GR00T model
+        # in __init__ via _create_groot_model()
+        policy = cls(config)
+
+        policy.eval()
+        return policy
+
     def get_optim_params(self) -> dict:
         return self.parameters()
 

src/lerobot/scripts/lerobot_edit_dataset.py

@@ -66,23 +66,23 @@ Remove camera feature:
         --operation.type remove_feature \
         --operation.feature_names "['observation.images.top']"
 
-Convert image dataset to video format (saves locally):
+Convert image dataset to video format and save locally:
     python -m lerobot.scripts.lerobot_edit_dataset \
         --repo_id lerobot/pusht_image \
-        --operation.type convert_to_video \
+        --operation.type convert_image_to_video \
         --operation.output_dir /path/to/output/pusht_video
 
-Convert image dataset and save with new repo_id:
+Convert image dataset to video format and save with new repo_id:
     python -m lerobot.scripts.lerobot_edit_dataset \
         --repo_id lerobot/pusht_image \
         --new_repo_id lerobot/pusht_video \
-        --operation.type convert_to_video
+        --operation.type convert_image_to_video
 
-Convert and push to hub:
+Convert image dataset to video format and push to hub:
     python -m lerobot.scripts.lerobot_edit_dataset \
         --repo_id lerobot/pusht_image \
         --new_repo_id lerobot/pusht_video \
-        --operation.type convert_to_video \
+        --operation.type convert_image_to_video \
         --push_to_hub true
 
 Using JSON config file:
@@ -92,24 +92,19 @@ Using JSON config file:
 
 import logging
 import shutil
-from concurrent.futures import ThreadPoolExecutor, as_completed
 from dataclasses import dataclass
 from pathlib import Path
 
-import pandas as pd
-from tqdm import tqdm
-
 from lerobot.configs import parser
 from lerobot.datasets.dataset_tools import (
+    convert_image_to_video_dataset,
     delete_episodes,
     merge_datasets,
     remove_feature,
     split_dataset,
 )
-from lerobot.datasets.lerobot_dataset import LeRobotDataset, LeRobotDatasetMetadata
+from lerobot.datasets.lerobot_dataset import LeRobotDataset
-from lerobot.datasets.utils import write_stats, write_tasks
+from lerobot.utils.constants import HF_LEROBOT_HOME
-from lerobot.datasets.video_utils import encode_video_frames, get_video_info
-from lerobot.utils.constants import HF_LEROBOT_HOME, OBS_IMAGE
 from lerobot.utils.utils import init_logging
 
 
@@ -138,8 +133,8 @@ class RemoveFeatureConfig:
 
 
 @dataclass
-class ConvertToVideoConfig:
+class ConvertImageToVideoConfig:
-    type: str = "convert_to_video"
+    type: str = "convert_image_to_video"
     output_dir: str | None = None
     vcodec: str = "libsvtav1"
     pix_fmt: str = "yuv420p"
@@ -148,12 +143,16 @@ class ConvertToVideoConfig:
     fast_decode: int = 0
     episode_indices: list[int] | None = None
     num_workers: int = 4
+    max_episodes_per_batch: int | None = None
+    max_frames_per_batch: int | None = None
 
 
 @dataclass
 class EditDatasetConfig:
     repo_id: str
-    operation: DeleteEpisodesConfig | SplitConfig | MergeConfig | RemoveFeatureConfig | ConvertToVideoConfig
+    operation: (
+        DeleteEpisodesConfig | SplitConfig | MergeConfig | RemoveFeatureConfig | ConvertImageToVideoConfig
+    )
     root: str | None = None
     new_repo_id: str | None = None
     push_to_hub: bool = False
@@ -297,362 +296,7 @@ def handle_remove_feature(cfg: EditDatasetConfig) -> None:
         LeRobotDataset(output_repo_id, root=output_dir).push_to_hub()
 
 
-def save_episode_images_for_video(
+def handle_convert_image_to_video(cfg: EditDatasetConfig) -> None:
-    dataset: LeRobotDataset,
-    imgs_dir: Path,
-    img_key: str,
-    episode_index: int,
-    num_workers: int = 4,
-) -> None:
-    """Save images from a specific episode and camera to disk for video encoding.
-
-    Args:
-        dataset: The LeRobot dataset to extract images from
-        imgs_dir: Directory to save images to
-        img_key: The image key (camera) to extract
-        episode_index: Index of the episode to save
-        num_workers: Number of threads for parallel image saving
-    """
-    # Create directory
-    imgs_dir.mkdir(parents=True, exist_ok=True)
-
-    # Get dataset without torch format for PIL image access
-    hf_dataset = dataset.hf_dataset.with_format(None)
-
-    # Select only this camera's images
-    imgs_dataset = hf_dataset.select_columns(img_key)
-
-    # Get episode start and end indices
-    from_idx = dataset.meta.episodes["dataset_from_index"][episode_index]
-    to_idx = dataset.meta.episodes["dataset_to_index"][episode_index]
-
-    # Get all items for this episode
-    episode_dataset = imgs_dataset.select(range(from_idx, to_idx))
-
-    # Define function to save a single image
-    def save_single_image(i_item_tuple):
-        i, item = i_item_tuple
-        img = item[img_key]
-        # Use frame-XXXXXX.png format to match encode_video_frames expectations
-        img.save(str(imgs_dir / f"frame-{i:06d}.png"), quality=100)
-        return i
-
-    # Save images with proper naming convention for encode_video_frames (frame-XXXXXX.png)
-    items = list(enumerate(episode_dataset))
-
-    with ThreadPoolExecutor(max_workers=num_workers) as executor:
-        futures = [executor.submit(save_single_image, item) for item in items]
-        for future in as_completed(futures):
-            future.result()  # This will raise any exceptions that occurred
-
-
-def encode_episode_videos(
-    dataset: LeRobotDataset,
-    new_meta: LeRobotDatasetMetadata,
-    episode_index: int,
-    vcodec: str,
-    pix_fmt: str,
-    g: int,
-    crf: int,
-    fast_decode: int,
-    temp_dir: Path,
-    num_image_workers: int = 4,
-) -> dict[str, dict]:
-    """Encode videos for a single episode and return video metadata.
-
-    Args:
-        dataset: Source dataset with images
-        new_meta: Metadata object for the new video dataset
-        episode_index: Episode index to process
-        vcodec: Video codec
-        pix_fmt: Pixel format
-        g: Group of pictures size
-        crf: Constant rate factor
-        fast_decode: Fast decode tuning
-        temp_dir: Temporary directory for images
-        num_image_workers: Number of workers for saving images
-
-    Returns:
-        Dictionary mapping video keys to their metadata (chunk_index, file_index, timestamps)
-    """
-    hf_dataset = dataset.hf_dataset.with_format(None)
-    img_keys = [key for key in hf_dataset.features if key.startswith(OBS_IMAGE)]
-
-    video_metadata = {}
-    fps = int(dataset.fps)  # Convert to int for PyAV compatibility
-    episode_length = dataset.meta.episodes["length"][episode_index]
-    episode_duration = episode_length / dataset.fps  # Use original fps for duration calculation
-
-    for img_key in img_keys:
-        # Save images temporarily
-        imgs_dir = temp_dir / f"episode_{episode_index:06d}" / img_key
-        save_episode_images_for_video(dataset, imgs_dir, img_key, episode_index, num_image_workers)
-
-        # Determine chunk and file indices
-        # For simplicity, we'll put each episode in its own file
-        chunk_idx = episode_index // new_meta.chunks_size
-        file_idx = episode_index % new_meta.chunks_size
-
-        # Create video path in the new dataset structure
-        video_path = new_meta.root / new_meta.video_path.format(
-            video_key=img_key, chunk_index=chunk_idx, file_index=file_idx
-        )
-        video_path.parent.mkdir(parents=True, exist_ok=True)
-
-        # Encode video
-        encode_video_frames(
-            imgs_dir=imgs_dir,
-            video_path=video_path,
-            fps=fps,
-            vcodec=vcodec,
-            pix_fmt=pix_fmt,
-            g=g,
-            crf=crf,
-            fast_decode=fast_decode,
-            overwrite=True,
-        )
-
-        # Clean up temporary images
-        shutil.rmtree(imgs_dir)
-
-        # Store video metadata
-        video_metadata[img_key] = {
-            f"videos/{img_key}/chunk_index": chunk_idx,
-            f"videos/{img_key}/file_index": file_idx,
-            f"videos/{img_key}/from_timestamp": 0.0,
-            f"videos/{img_key}/to_timestamp": episode_duration,
-        }
-
-    return video_metadata
-
-
-def convert_dataset_to_videos(
-    dataset: LeRobotDataset,
-    output_dir: Path,
-    repo_id: str | None = None,
-    vcodec: str = "libsvtav1",
-    pix_fmt: str = "yuv420p",
-    g: int = 2,
-    crf: int = 30,
-    fast_decode: int = 0,
-    episode_indices: list[int] | None = None,
-    num_workers: int = 4,
-) -> LeRobotDataset:
-    """Convert image-based dataset to video-based dataset.
-
-    Creates a new LeRobotDataset with videos instead of images, following the proper
-    LeRobot dataset structure with videos stored in chunked MP4 files.
-
-    Args:
-        dataset: The source LeRobot dataset with images
-        output_dir: Directory to save the new video dataset
-        repo_id: Repository ID for the new dataset (default: original_id + "_video")
-        vcodec: Video codec (default: libsvtav1)
-        pix_fmt: Pixel format (default: yuv420p)
-        g: Group of pictures size (default: 2)
-        crf: Constant rate factor (default: 30)
-        fast_decode: Fast decode tuning (default: 0)
-        episode_indices: List of episode indices to convert (None = all episodes)
-        num_workers: Number of threads for parallel processing (default: 4)
-
-    Returns:
-        New LeRobotDataset with videos
-    """
-    # Check that it's an image dataset
-    if len(dataset.meta.video_keys) > 0:
-        raise ValueError(
-            f"This operation is for image datasets only. Video dataset provided: {dataset.repo_id}"
-        )
-
-    # Get all image keys
-    hf_dataset = dataset.hf_dataset.with_format(None)
-    img_keys = [key for key in hf_dataset.features if key.startswith(OBS_IMAGE)]
-
-    if len(img_keys) == 0:
-        raise ValueError(f"No image keys found in dataset {dataset.repo_id}")
-
-    # Determine which episodes to process
-    if episode_indices is None:
-        episode_indices = list(range(dataset.meta.total_episodes))
-
-    if repo_id is None:
-        repo_id = f"{dataset.repo_id}_video"
-
-    logging.info(
-        f"Converting {len(episode_indices)} episodes with {len(img_keys)} cameras from {dataset.repo_id}"
-    )
-    logging.info(f"Video codec: {vcodec}, pixel format: {pix_fmt}, GOP: {g}, CRF: {crf}")
-
-    # Create new features dict, converting image features to video features
-    new_features = {}
-    for key, value in dataset.meta.features.items():
-        if key not in img_keys:
-            new_features[key] = value
-        else:
-            # Convert image key to video format
-            new_features[key] = value.copy()
-            new_features[key]["dtype"] = "video"  # Change dtype from "image" to "video"
-            # Video info will be updated after episodes are encoded
-
-    # Create new metadata for video dataset
-    new_meta = LeRobotDatasetMetadata.create(
-        repo_id=repo_id,
-        fps=dataset.meta.fps,
-        features=new_features,
-        robot_type=dataset.meta.robot_type,
-        root=output_dir,
-        use_videos=True,
-        chunks_size=dataset.meta.chunks_size,
-        data_files_size_in_mb=dataset.meta.data_files_size_in_mb,
-        video_files_size_in_mb=dataset.meta.video_files_size_in_mb,
-    )
-
-    # Create temporary directory for image extraction
-    temp_dir = output_dir / "temp_images"
-    temp_dir.mkdir(parents=True, exist_ok=True)
-
-    # Process each episode
-    all_episode_metadata = []
-
-    try:
-        for ep_idx in tqdm(episode_indices, desc="Converting episodes to videos"):
-            # Get episode metadata from source
-            src_episode = dataset.meta.episodes[ep_idx]
-
-            # Encode videos for this episode
-            video_metadata = encode_episode_videos(
-                dataset=dataset,
-                new_meta=new_meta,
-                episode_index=ep_idx,
-                vcodec=vcodec,
-                pix_fmt=pix_fmt,
-                g=g,
-                crf=crf,
-                fast_decode=fast_decode,
-                temp_dir=temp_dir,
-                num_image_workers=num_workers,
-            )
-
-            # Build episode metadata
-            episode_meta = {
-                "episode_index": ep_idx,
-                "length": src_episode["length"],
-                "dataset_from_index": ep_idx * src_episode["length"],
-                "dataset_to_index": (ep_idx + 1) * src_episode["length"],
-            }
-
-            # Add video metadata
-            for img_key in img_keys:
-                episode_meta.update(video_metadata[img_key])
-
-            # Add data chunk/file info (using same structure as source)
-            if "data/chunk_index" in src_episode:
-                episode_meta["data/chunk_index"] = src_episode["data/chunk_index"]
-                episode_meta["data/file_index"] = src_episode["data/file_index"]
-
-            all_episode_metadata.append(episode_meta)
-
-        # Copy and transform data files (removing image columns)
-        _copy_data_without_images(dataset, new_meta, episode_indices, img_keys)
-
-        # Save episode metadata
-        episodes_df = pd.DataFrame(all_episode_metadata)
-        episodes_path = new_meta.root / "meta" / "episodes" / "chunk-000" / "file-000.parquet"
-        episodes_path.parent.mkdir(parents=True, exist_ok=True)
-        episodes_df.to_parquet(episodes_path, index=False)
-
-        # Update metadata info
-        new_meta.info["total_episodes"] = len(episode_indices)
-        new_meta.info["total_frames"] = sum(ep["length"] for ep in all_episode_metadata)
-        new_meta.info["total_tasks"] = dataset.meta.total_tasks
-        new_meta.info["splits"] = {"train": f"0:{len(episode_indices)}"}
-
-        # Update video info for all image keys (now videos)
-        # We need to manually set video info since update_video_info() checks video_keys first
-        for img_key in img_keys:
-            if not new_meta.features[img_key].get("info", None):
-                video_path = new_meta.root / new_meta.video_path.format(
-                    video_key=img_key, chunk_index=0, file_index=0
-                )
-                new_meta.info["features"][img_key]["info"] = get_video_info(video_path)
-
-        from lerobot.datasets.utils import write_info
-
-        write_info(new_meta.info, new_meta.root)
-
-        # Copy stats and tasks
-        if dataset.meta.stats is not None:
-            # Remove image stats
-            new_stats = {k: v for k, v in dataset.meta.stats.items() if k not in img_keys}
-            write_stats(new_stats, new_meta.root)
-
-        if dataset.meta.tasks is not None:
-            write_tasks(dataset.meta.tasks, new_meta.root)
-
-    finally:
-        # Clean up temporary directory
-        if temp_dir.exists():
-            shutil.rmtree(temp_dir)
-
-    logging.info(f"✓ Completed converting {dataset.repo_id} to video format")
-    logging.info(f"New dataset saved to: {output_dir}")
-
-    # Return new dataset
-    return LeRobotDataset(repo_id=repo_id, root=output_dir)
-
-
-def _copy_data_without_images(
-    src_dataset: LeRobotDataset,
-    dst_meta: LeRobotDatasetMetadata,
-    episode_indices: list[int],
-    img_keys: list[str],
-) -> None:
-    """Copy data files without image columns.
-
-    Args:
-        src_dataset: Source dataset
-        dst_meta: Destination metadata
-        episode_indices: Episodes to include
-        img_keys: Image keys to remove
-    """
-    from lerobot.datasets.utils import DATA_DIR
-
-    data_dir = src_dataset.root / DATA_DIR
-    parquet_files = sorted(data_dir.glob("*/*.parquet"))
-
-    if not parquet_files:
-        raise ValueError(f"No parquet files found in {data_dir}")
-
-    episode_set = set(episode_indices)
-
-    for src_path in tqdm(parquet_files, desc="Processing data files"):
-        df = pd.read_parquet(src_path).reset_index(drop=True)
-
-        # Filter to only include selected episodes
-        df = df[df["episode_index"].isin(episode_set)].copy()
-
-        if len(df) == 0:
-            continue
-
-        # Remove image columns
-        columns_to_drop = [col for col in img_keys if col in df.columns]
-        if columns_to_drop:
-            df = df.drop(columns=columns_to_drop)
-
-        # Get chunk and file indices from path
-        relative_path = src_path.relative_to(src_dataset.root)
-        chunk_dir = relative_path.parts[1]
-        file_name = relative_path.parts[2]
-        chunk_idx = int(chunk_dir.split("-")[1])
-        file_idx = int(file_name.split("-")[1].split(".")[0])
-
-        # Write to destination without pandas index
-        dst_path = dst_meta.root / f"data/chunk-{chunk_idx:03d}/file-{file_idx:03d}.parquet"
-        dst_path.parent.mkdir(parents=True, exist_ok=True)
-        df.to_parquet(dst_path, index=False)
-
-
-def handle_convert_to_video(cfg: EditDatasetConfig) -> None:
     # Note: Parser may create any config type with the right fields, so we access fields directly
     # instead of checking isinstance()
     dataset = LeRobotDataset(cfg.repo_id, root=cfg.root)
@@ -664,8 +308,12 @@ def handle_convert_to_video(cfg: EditDatasetConfig) -> None:
     if cfg.new_repo_id:
         # Use new_repo_id for both local storage and hub push
         output_repo_id = cfg.new_repo_id
-        output_dir = Path(cfg.root) / cfg.new_repo_id if cfg.root else HF_LEROBOT_HOME / cfg.new_repo_id
+        # Place new dataset as a sibling to the original dataset
-        logging.info(f"Saving to new dataset: {cfg.new_repo_id}")
+        # Get the parent of the actual dataset root (not cfg.root which might be the lerobot cache dir)
+        # Extract just the dataset name (after last slash) for the local directory
+        local_dir_name = cfg.new_repo_id.split("/")[-1]
+        output_dir = dataset.root.parent / local_dir_name
+        logging.info(f"Saving to new dataset: {cfg.new_repo_id} at {output_dir}")
     elif output_dir_config:
         # Use custom output directory for local-only storage
         output_dir = Path(output_dir_config)
@@ -675,12 +323,15 @@ def handle_convert_to_video(cfg: EditDatasetConfig) -> None:
     else:
         # Auto-generate name: append "_video" to original repo_id
         output_repo_id = f"{cfg.repo_id}_video"
-        output_dir = Path(cfg.root) / output_repo_id if cfg.root else HF_LEROBOT_HOME / output_repo_id
+        # Place new dataset as a sibling to the original dataset
+        # Extract just the dataset name (after last slash) for the local directory
+        local_dir_name = output_repo_id.split("/")[-1]
+        output_dir = dataset.root.parent / local_dir_name
         logging.info(f"Saving to auto-generated location: {output_dir}")
 
     logging.info(f"Converting dataset {cfg.repo_id} to video format")
 
-    new_dataset = convert_dataset_to_videos(
+    new_dataset = convert_image_to_video_dataset(
         dataset=dataset,
         output_dir=output_dir,
         repo_id=output_repo_id,
@@ -691,6 +342,8 @@ def handle_convert_to_video(cfg: EditDatasetConfig) -> None:
         fast_decode=getattr(cfg.operation, "fast_decode", 0),
         episode_indices=getattr(cfg.operation, "episode_indices", None),
         num_workers=getattr(cfg.operation, "num_workers", 4),
+        max_episodes_per_batch=getattr(cfg.operation, "max_episodes_per_batch", None),
+        max_frames_per_batch=getattr(cfg.operation, "max_frames_per_batch", None),
     )
 
     logging.info("Video dataset created successfully!")
@@ -718,8 +371,8 @@ def edit_dataset(cfg: EditDatasetConfig) -> None:
         handle_merge(cfg)
     elif operation_type == "remove_feature":
         handle_remove_feature(cfg)
-    elif operation_type == "convert_to_video":
+    elif operation_type == "convert_image_to_video":
-        handle_convert_to_video(cfg)
+        handle_convert_image_to_video(cfg)
     else:
         raise ValueError(
             f"Unknown operation type: {operation_type}\n"

tests/async_inference/test_e2e.py

@@ -144,12 +144,18 @@ def test_async_inference_e2e(monkeypatch):
     client = RobotClient(client_config)
     assert client.start(), "Client failed initial handshake with the server"
 
-    # Track action chunks received without modifying RobotClient
+    # Track action chunks received and verify device type
-    action_chunks_received = {"count": 0}
+    action_chunks_received = {"count": 0, "actions_on_cpu": True}
     original_aggregate = client._aggregate_action_queues
 
     def counting_aggregate(*args, **kwargs):
         action_chunks_received["count"] += 1
+        # Check that all received actions are on CPU
+        if args:
+            for timed_action in args[0]:  # args[0] is the list of TimedAction
+                action_tensor = timed_action.get_action()
+                if action_tensor.device.type != "cpu":
+                    action_chunks_received["actions_on_cpu"] = False
         return original_aggregate(*args, **kwargs)
 
     monkeypatch.setattr(client, "_aggregate_action_queues", counting_aggregate)

tests/datasets/test_aggregate.py

@@ -16,6 +16,7 @@
 
 from unittest.mock import patch
 
+import datasets
 import torch
 
 from lerobot.datasets.aggregate import aggregate_datasets
@@ -380,3 +381,147 @@ def test_video_timestamps_regression(tmp_path, lerobot_dataset_factory):
         for key in aggr_ds.meta.video_keys:
             assert key in item, f"Video key {key} missing from item {i}"
             assert item[key].shape[0] == 3, f"Expected 3 channels for video key {key}"
+
+
+def assert_image_schema_preserved(aggr_ds):
+    """Test that HuggingFace Image feature schema is preserved in aggregated parquet files.
+
+    This verifies the fix for a bug where image columns were written with a generic
+    struct schema {'bytes': Value('binary'), 'path': Value('string')} instead of
+    the proper Image() feature type, causing HuggingFace Hub viewer to display
+    raw dict objects instead of image thumbnails.
+    """
+    image_keys = aggr_ds.meta.image_keys
+    if not image_keys:
+        return
+
+    # Check that parquet files have proper Image schema
+    data_dir = aggr_ds.root / "data"
+    parquet_files = list(data_dir.rglob("*.parquet"))
+    assert len(parquet_files) > 0, "No parquet files found in aggregated dataset"
+
+    for parquet_file in parquet_files:
+        # Load with HuggingFace datasets to check schema
+        ds = datasets.Dataset.from_parquet(str(parquet_file))
+
+        for image_key in image_keys:
+            feature = ds.features.get(image_key)
+            assert feature is not None, f"Image key '{image_key}' not found in parquet schema"
+            assert isinstance(feature, datasets.Image), (
+                f"Image key '{image_key}' should have Image() feature type, "
+                f"but got {type(feature).__name__}: {feature}. "
+                "This indicates image schema was not preserved during aggregation."
+            )
+
+
+def assert_image_frames_integrity(aggr_ds, ds_0, ds_1):
+    """Test that image frames are correctly preserved after aggregation."""
+    image_keys = aggr_ds.meta.image_keys
+    if not image_keys:
+        return
+
+    def images_equal(img1, img2):
+        return torch.allclose(img1, img2)
+
+    # Test the section corresponding to the first dataset (ds_0)
+    for i in range(len(ds_0)):
+        assert aggr_ds[i]["index"] == i, (
+            f"Frame index at position {i} should be {i}, but got {aggr_ds[i]['index']}"
+        )
+        for key in image_keys:
+            assert images_equal(aggr_ds[i][key], ds_0[i][key]), (
+                f"Image frames at position {i} should be equal between aggregated and ds_0"
+            )
+
+    # Test the section corresponding to the second dataset (ds_1)
+    for i in range(len(ds_0), len(ds_0) + len(ds_1)):
+        assert aggr_ds[i]["index"] == i, (
+            f"Frame index at position {i} should be {i}, but got {aggr_ds[i]['index']}"
+        )
+        for key in image_keys:
+            assert images_equal(aggr_ds[i][key], ds_1[i - len(ds_0)][key]), (
+                f"Image frames at position {i} should be equal between aggregated and ds_1"
+            )
+
+
+def test_aggregate_image_datasets(tmp_path, lerobot_dataset_factory):
+    """Test aggregation of image-based datasets preserves HuggingFace Image schema.
+
+    This test specifically verifies that:
+    1. Image-based datasets can be aggregated correctly
+    2. The HuggingFace Image() feature type is preserved in parquet files
+    3. Image data integrity is maintained across aggregation
+    4. Images can be properly decoded after aggregation
+
+    This catches the bug where to_parquet_with_hf_images() was not passing
+    the features schema, causing image columns to be written as generic
+    struct types instead of Image() types.
+    """
+    ds_0_num_frames = 50
+    ds_1_num_frames = 75
+    ds_0_num_episodes = 2
+    ds_1_num_episodes = 3
+
+    # Create two image-based datasets (use_videos=False)
+    ds_0 = lerobot_dataset_factory(
+        root=tmp_path / "image_0",
+        repo_id=f"{DUMMY_REPO_ID}_image_0",
+        total_episodes=ds_0_num_episodes,
+        total_frames=ds_0_num_frames,
+        use_videos=False,  # Image-based dataset
+    )
+    ds_1 = lerobot_dataset_factory(
+        root=tmp_path / "image_1",
+        repo_id=f"{DUMMY_REPO_ID}_image_1",
+        total_episodes=ds_1_num_episodes,
+        total_frames=ds_1_num_frames,
+        use_videos=False,  # Image-based dataset
+    )
+
+    # Verify source datasets have image keys
+    assert len(ds_0.meta.image_keys) > 0, "ds_0 should have image keys"
+    assert len(ds_1.meta.image_keys) > 0, "ds_1 should have image keys"
+
+    # Aggregate the datasets
+    aggregate_datasets(
+        repo_ids=[ds_0.repo_id, ds_1.repo_id],
+        roots=[ds_0.root, ds_1.root],
+        aggr_repo_id=f"{DUMMY_REPO_ID}_image_aggr",
+        aggr_root=tmp_path / "image_aggr",
+    )
+
+    # Load the aggregated dataset
+    with (
+        patch("lerobot.datasets.lerobot_dataset.get_safe_version") as mock_get_safe_version,
+        patch("lerobot.datasets.lerobot_dataset.snapshot_download") as mock_snapshot_download,
+    ):
+        mock_get_safe_version.return_value = "v3.0"
+        mock_snapshot_download.return_value = str(tmp_path / "image_aggr")
+        aggr_ds = LeRobotDataset(f"{DUMMY_REPO_ID}_image_aggr", root=tmp_path / "image_aggr")
+
+    # Verify aggregated dataset has image keys
+    assert len(aggr_ds.meta.image_keys) > 0, "Aggregated dataset should have image keys"
+    assert aggr_ds.meta.image_keys == ds_0.meta.image_keys, "Image keys should match source datasets"
+
+    # Run standard aggregation assertions
+    expected_total_episodes = ds_0_num_episodes + ds_1_num_episodes
+    expected_total_frames = ds_0_num_frames + ds_1_num_frames
+
+    assert_episode_and_frame_counts(aggr_ds, expected_total_episodes, expected_total_frames)
+    assert_dataset_content_integrity(aggr_ds, ds_0, ds_1)
+    assert_metadata_consistency(aggr_ds, ds_0, ds_1)
+    assert_episode_indices_updated_correctly(aggr_ds, ds_0, ds_1)
+
+    # Image-specific assertions
+    assert_image_schema_preserved(aggr_ds)
+    assert_image_frames_integrity(aggr_ds, ds_0, ds_1)
+
+    # Verify images can be accessed and have correct shape
+    sample_item = aggr_ds[0]
+    for image_key in aggr_ds.meta.image_keys:
+        img = sample_item[image_key]
+        assert isinstance(img, torch.Tensor), f"Image {image_key} should be a tensor"
+        assert img.dim() == 3, f"Image {image_key} should have 3 dimensions (C, H, W)"
+        assert img.shape[0] == 3, f"Image {image_key} should have 3 channels"
+
+    assert_dataset_iteration_works(aggr_ds)

tests/datasets/test_dataset_tools.py

@@ -29,7 +29,7 @@ from lerobot.datasets.dataset_tools import (
     remove_feature,
     split_dataset,
 )
-from lerobot.scripts.lerobot_edit_dataset import convert_dataset_to_videos
+from lerobot.scripts.lerobot_edit_dataset import convert_image_to_video_dataset
 
 
 @pytest.fixture
@@ -1050,7 +1050,7 @@ def test_modify_features_preserves_file_structure(sample_dataset, tmp_path):
         assert "reward" in modified_dataset.meta.features
 
 
-def test_convert_dataset_to_videos(tmp_path):
+def test_convert_image_to_video_dataset(tmp_path):
     """Test converting lerobot/pusht_image dataset to video format."""
     from lerobot.datasets.lerobot_dataset import LeRobotDataset
 
@@ -1071,7 +1071,7 @@ def test_convert_dataset_to_videos(tmp_path):
         assert "observation.image" in source_dataset.meta.features
 
         # Convert to video dataset (only first 2 episodes for speed)
-        video_dataset = convert_dataset_to_videos(
+        video_dataset = convert_image_to_video_dataset(
             dataset=source_dataset,
             output_dir=output_dir,
             repo_id="lerobot/pusht_video",
@@ -1113,7 +1113,7 @@ def test_convert_dataset_to_videos(tmp_path):
             shutil.rmtree(output_dir)
 
 
-def test_convert_dataset_to_videos_subset_episodes(tmp_path):
+def test_convert_image_to_video_dataset_subset_episodes(tmp_path):
     """Test converting only specific episodes from lerobot/pusht_image to video format."""
     from lerobot.datasets.lerobot_dataset import LeRobotDataset
 
@@ -1132,7 +1132,7 @@ def test_convert_dataset_to_videos_subset_episodes(tmp_path):
         # Convert only episode 0 to video (subset of loaded episodes)
         episode_indices = [0]
 
-        video_dataset = convert_dataset_to_videos(
+        video_dataset = convert_image_to_video_dataset(
             dataset=source_dataset,
             output_dir=output_dir,
             repo_id="lerobot/pusht_video_subset",