chore(fromat): formatting code

docs/source/_toctree.yml

@@ -33,6 +33,8 @@
     title: Using the Dataset Tools
   - local: dataset_subtask
     title: Using Subtasks in the Dataset
+  - local: video_encoding_parameters
+    title: Video encoding parameters
   - local: streaming_video_encoding
     title: Streaming Video Encoding
   title: "Datasets"

docs/source/streaming_video_encoding.mdx

@@ -14,22 +14,12 @@ This makes `save_episode()` near-instant (the video is already encoded by the ti
 
 ## 2. Tuning Parameters
 
-All encoding parameters are grouped under `camera_encoder_config` (a `VideoEncoderConfig` dataclass), accessible from the CLI via `--dataset.camera_encoder_config.<field>`.
-
-| Parameter               | CLI Flag                                      | Type          | Default       | Description                                                         |
-| ----------------------- | --------------------------------------------- | ------------- | ------------- | ------------------------------------------------------------------- |
-| `streaming_encoding`    | `--dataset.streaming_encoding`                | `bool`        | `True`        | Enable real-time encoding during capture                            |
-| `vcodec`                | `--dataset.camera_encoder_config.vcodec`      | `str`         | `"libsvtav1"` | Video codec. `"auto"` detects best HW encoder                       |
-| `pix_fmt`               | `--dataset.camera_encoder_config.pix_fmt`     | `str`         | `"yuv420p"`   | Pixel format                                                        |
-| `g`                     | `--dataset.camera_encoder_config.g`           | `int \| None` | `2`           | GOP size (keyframe interval)                                        |
-| `crf`                   | `--dataset.camera_encoder_config.crf`         | `int \| None` | `30`          | Quality level (mapped to codec-specific parameter)                  |
-| `preset`                | `--dataset.camera_encoder_config.preset`      | `int \| None` | `12`          | Speed preset (libsvtav1 only, 0 = slowest … 13 = fastest)           |
-| `fast_decode`           | `--dataset.camera_encoder_config.fast_decode` | `int`         | `0`           | Fast-decode tuning level                                            |
-| `encoder_threads`       | `--dataset.encoder_threads`                   | `int \| None` | `None` (auto) | Threads per encoder instance (global). `None` lets the codec decide |
-| `encoder_queue_maxsize` | `--dataset.encoder_queue_maxsize`             | `int`         | `60`          | Max buffered frames per camera (~2s at 30fps). Consumes RAM         |
-
-> [!TIP]
-> Not all parameters apply to every codec. `VideoEncoderConfig` will warn at startup if you set a parameter that your chosen codec ignores (e.g. `preset` with `h264_nvenc`).
+| Parameter               | CLI Flag                                 | Type          | Default       | Description                                                       |
+| ----------------------- | ---------------------------------------- | ------------- | ------------- | ----------------------------------------------------------------- |
+| `streaming_encoding`    | `--dataset.streaming_encoding`           | `bool`        | `True`        | Enable real-time encoding during capture                          |
+| `vcodec`                | `--dataset.camera_encoder_config.vcodec` | `str`         | `"libsvtav1"` | Video codec. `"auto"` detects best HW encoder                     |
+| `encoder_threads`       | `--dataset.encoder_threads`              | `int \| None` | `None` (auto) | Threads per encoder instance. `None` will leave the vcoded decide |
+| `encoder_queue_maxsize` | `--dataset.encoder_queue_maxsize`        | `int`         | `60`          | Max buffered frames per camera (~2s at 30fps). Consumes RAM       |
 
 ## 3. Performance Considerations
 
@@ -50,7 +40,7 @@ Streaming encoding means the CPU is encoding video **during** the capture loop,
 
 ### `encoder_threads` Tuning
 
-This parameter (`--dataset.encoder_threads`) controls how many threads each encoder instance uses internally:
+This parameter controls how many threads each encoder instance uses internally:
 
 - **Higher values** (e.g., 4-5): Faster encoding, but uses more CPU cores per camera. Good for high-end systems with many cores.
 - **Lower values** (e.g., 1-2): Less CPU per camera, freeing cores for capture and visualization. Good for low-res images and capable CPUs.
@@ -58,7 +48,7 @@ This parameter (`--dataset.encoder_threads`) controls how many threads each enco
 
 ### Backpressure and Frame Dropping
 
-Each camera has a bounded queue (`encoder_queue_maxsize`, default 60 frames). When the encoder can't keep up:
+Each camera has a bounded queue (`encoder_queue_maxsize`, default 30 frames). When the encoder can't keep up:
 
 1. The queue fills up (consuming RAM)
 2. New frames are **dropped** (not blocked) — the capture loop continues uninterrupted
@@ -162,4 +152,4 @@ lerobot-record --dataset.camera_encoder_config.vcodec=h264 --dataset.streaming_e
 ## 7. Closing note
 
 Performance ultimately depends on your exact setup — frames-per-second, resolution, CPU cores and load, available memory, episode length, and the encoder you choose. Always test with your target workload, be mindful about your CPU & system capabilities and tune `encoder_threads`, `encoder_queue_maxsize`, and
-`camera_encoder_config.vcodec` reasonably. That said, a common practical configuration (for many applications) is three cameras at 640×480x3 @30fps; this usually runs fine with the default streaming video encoding settings in modern systems. Always verify your recorded dataset is healthy by comparing the video duration to the CLI episode duration and confirming the row count equals FPS × CLI duration.
+`vcodec` reasonably. That said, a common practical configuration (for many applications) is three cameras at 640×480x3 @30fps; this usually runs fine with the default streaming video encoding settings in modern systems. Always verify your recorded dataset is healthy by comparing the video duration to the CLI episode duration and confirming the row count equals FPS × CLI duration.

docs/source/using_dataset_tools.mdx

@@ -147,14 +147,7 @@ lerobot-edit-dataset \
 **Parameters:**
 
 - `output_dir`: Custom output directory (optional - by default uses `new_repo_id` or `{repo_id}_video`)
-- `camera_encoder_config`: Video encoder settings — all sub-fields accessible via `--operation.camera_encoder_config.<field>`:
-  - `vcodec`: Video codec — `h264`, `hevc`, `libsvtav1`, `auto`, or hardware codecs (default: `libsvtav1`)
-  - `pix_fmt`: Pixel format — `yuv420p`, `yuv444p` (default: `yuv420p`)
-  - `g`: GOP size — lower values give better quality but larger files (default: 2)
-  - `crf`: Quality level — lower is better, 0 is lossless (default: 30)
-  - `preset`: Speed preset, libsvtav1 only (default: 12)
-  - `fast_decode`: Fast-decode tuning (default: 0)
-  - `encoder_threads`: Threads per encoder instance — global setting, separate from `camera_encoder_config` (default: None)
+- `camera_encoder_config`: Video encoder settings — all sub-fields accessible via `--operation.camera_encoder_config.<field>. See [Video Encoding Parameters](./video_encoding_parameters) for more details.
 - `episode_indices`: List of specific episodes to convert (default: all episodes)
 - `num_workers`: Number of parallel workers for processing (default: 4)
 

docs/source/video_encoding_parameters.mdx

@@ -0,0 +1,81 @@
+# Video encoding parameters
+
+When **video storage** is on, LeRobot stores each camera stream as an **MP4** file rather than saving **every timestep as its own image file**. **Video encoding compress across time**, which usually cuts **dataset size and I/O** compared to heaps of PNGs, and MP4 stays a **familiar format** for players and loaders. Incoding frames into a MP4 file is a full FFmpeg pipeline: choice of encoder, pixel format, GOP/keyframes, quality vs speed, and
+optional extra encoder flags. **Many of those knobs are user-tunable** and are exposed on the dataset config as
+**`dataset.camera_encoder_config`** — a nested **`VideoEncoderConfig`** (`lerobot.datasets.video_utils.
+VideoEncoderConfig`) passed through **PyAV**.
+
+You can set these parameters from the CLI with **`--dataset.camera_encoder_config.<field>`** (e.g. `lerobot-record`, `lerobot-rollout`). The same block applies to **every** camera video stream in that run. **Video storage must be on** — **`use_videos=True`** in Python APIs or **`--dataset.video=true`** (recording default); with video off, inputs stay as images and **`camera_encoder_config` is ignored.**
+
+For **when** frames are written vs encoded (streaming vs post-episode), queues, and other top-level **`--dataset.*`** switches, see [Streaming Video Encoding](./streaming_video_encoding). For codec/size/speed experiments, see the [video-benchmark Space](https://huggingface.co/spaces/lerobot/video-benchmark).
+
+---
+
+## Tuning Parameters
+
+| Parameter       | CLI flag                                        | Type                 | Default       | Description                                                                                                                                             |
+| --------------- | ----------------------------------------------- | -------------------- | ------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| `vcodec`        | `--dataset.camera_encoder_config.vcodec`        | `str`                | `"libsvtav1"` | Video codec name. `"auto"` picks the first available hardware encoder from a fixed preference list, else `libsvtav1`.                                   |
+| `pix_fmt`       | `--dataset.camera_encoder_config.pix_fmt`       | `str`                | `"yuv420p"`   | Output pixel format; must be supported by the specified codec in your FFmpeg build.                                                                     |
+| `g`             | `--dataset.camera_encoder_config.g`             | `int \| None`        | `2`           | GOP size (keyframes every `g` frames). Emitted as FFmpeg option `g`.                                                                                    |
+| `crf`           | `--dataset.camera_encoder_config.crf`           | `int \| None`        | `30`          | Abstract **quality**; mapped per codec in the table below (CRF, QP, `q:v`, etc.). Lower → higher quality / larger output where the mapping is monotone. |
+| `preset`        | `--dataset.camera_encoder_config.preset`        | `int \| str \| None` | `12`\*        | Video encoding speed preset; meaning depends on the specified codec. \*Unset + `libsvtav1` → LeRobot sets `12`.                                         |
+| `fast_decode`   | `--dataset.camera_encoder_config.fast_decode`   | `int`                | `0`           | `libsvtav1`: `0–2` passed in `svtav1-params`; `h264` / `hevc` (software): if `>0`, sets `tune=fastdecode`; other codecs: often unused.                  |
+| `video_backend` | `--dataset.camera_encoder_config.video_backend` | `str`                | `"pyav"`      | Only `"pyav"` is implemented for video encoding today.                                                                                                  |
+| `extra_options` | (nested config / non-scalar)                    | `dict`               | `{}`          | Extra FFmpeg options merged after the built-in mapping; **cannot** override keys already set from structured fields above.                              |
+
+---
+
+## Validation
+
+| What                 | Behavior                                                                                                                                                                                        |
+| -------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| Video codec presence | `vcodec` must exist as a video encoder in the local FFmpeg build (after resolving `"auto"`).                                                                                                    |
+| Pixel format         | `pix_fmt` is checked against the encoder’s reported pixel formats when available.                                                                                                               |
+| Options              | `get_codec_options()` output (including values originating from `extra_options`) is checked against PyAV/FFmpeg option metadata (ranges, integer constraints, string choices) where applicable. |
+
+---
+
+## Mapping: `VideoEncoderConfig` → FFmpeg options
+
+From **`get_codec_options()`** after `vcodec` resolution. Only fields on `camera_encoder_config` are listed here (no global thread / queue flags).
+
+| Resolved `vcodec`                        | `g` | Quality from `crf`          | `preset` | `fast_decode`                              |
+| ---------------------------------------- | --- | --------------------------- | -------- | ------------------------------------------ |
+| `libsvtav1`                              | `g` | `crf`                       | `preset` | `svtav1-params` includes `fast-decode=0…2` |
+| `h264`, `hevc` (software)                | `g` | `crf`                       | `preset` | `tune=fastdecode` if `fast_decode > 0`     |
+| `h264_videotoolbox`, `hevc_videotoolbox` | `g` | `q:v` (derived from `crf`)  | —        | —                                          |
+| `h264_nvenc`, `hevc_nvenc`               | `g` | `rc=constqp` + `qp` ← `crf` | `preset` | —                                          |
+| `h264_vaapi`                             | `g` | `qp` ← `crf`                | —        | —                                          |
+| `h264_qsv`                               | `g` | `global_quality` ← `crf`    | `preset` | —                                          |
+
+---
+
+## `extra_options`
+
+- Merged **after** structured options; keys **already** set by `g`, `crf`, `preset`, etc. are **not** replaced by `extra_options`.
+- Values are strings or numbers as FFmpeg expects; numeric values are validated when the codec exposes option metadata.
+
+---
+
+## Example
+
+```bash
+lerobot-record \
+    --robot.type=so100_follower \
+    --robot.port=/dev/tty.usbmodem58760431541 \
+    --robot.cameras="{laptop: {type: opencv, index_or_path: 0, width: 640, height: 480, fps: 30}}" \
+    --robot.id=black \
+    --teleop.type=so100_leader \
+    --teleop.port=/dev/tty.usbmodem58760431551 \
+    --teleop.id=blue \
+    --dataset.repo_id=<my_username>/<my_dataset_name> \
+    --dataset.num_episodes=2 \
+    --dataset.single_task="Grab the cube" \
+    --dataset.streaming_encoding=true \
+    --dataset.encoder_threads=2 \
+    --dataset.camera_encoder_config.vcodec=h264 \
+    --dataset.camera_encoder_config.preset=fast \
+    --dataset.camera_encoder_config.extra_options={"tune": "film", "profile:v": "high", "bf": 2} \
+    --display_data=true
+```

src/lerobot/configs/dataset.py

@@ -14,10 +14,12 @@
 
 """Shared dataset recording configuration used by both ``lerobot-record`` and ``lerobot-rollout``."""
 
-from dataclasses import dataclass
+from dataclasses import dataclass, field
 from datetime import datetime
 from pathlib import Path
 
+from lerobot.datasets.video_utils import VideoEncoderConfig, camera_encoder_defaults
+
 
 @dataclass
 class DatasetRecordConfig:
@@ -55,10 +57,9 @@ class DatasetRecordConfig:
     # Number of episodes to record before batch encoding videos
     # Set to 1 for immediate encoding (default behavior), or higher for batched encoding
     video_encoding_batch_size: int = 1
-    # Video codec for encoding videos. Options: 'h264', 'hevc', 'libsvtav1', 'auto',
-    # or hardware-specific: 'h264_videotoolbox', 'h264_nvenc', 'h264_vaapi', 'h264_qsv'.
-    # Use 'auto' to auto-detect the best available hardware encoder.
-    vcodec: str = "libsvtav1"
+    # Video encoder settings for camera MP4s (codec, quality, GOP, etc.). Tuned via CLI nested keys,
+    # e.g. ``--dataset.camera_encoder_config.vcodec=h264`` (see ``VideoEncoderConfig``).
+    camera_encoder_config: VideoEncoderConfig = field(default_factory=camera_encoder_defaults)
     # Enable streaming video encoding: encode frames in real-time during capture instead
     # of writing PNG images first. Makes save_episode() near-instant. More info in the documentation: https://huggingface.co/docs/lerobot/streaming_video_encoding
     streaming_encoding: bool = False

src/lerobot/datasets/dataset_tools.py

@@ -62,7 +62,12 @@ from .utils import (
     DEFAULT_EPISODES_PATH,
     update_chunk_file_indices,
 )
-from .video_utils import VideoEncoderConfig, encode_video_frames, get_video_info
+from .video_utils import (
+    VideoEncoderConfig,
+    camera_encoder_defaults,
+    encode_video_frames,
+    get_video_info,
+)
 
 
 def _load_episode_with_stats(src_dataset: LeRobotDataset, episode_idx: int) -> dict:
@@ -101,7 +106,8 @@ def delete_episodes(
         episode_indices: List of episode indices to delete.
         output_dir: Root directory where the edited dataset will be stored. If not specified, defaults to $HF_LEROBOT_HOME/repo_id. Equivalent to new_root in EditDatasetConfig.
         repo_id: Edited dataset identifier. Equivalent to new_repo_id in EditDatasetConfig.
-        camera_encoder_config: Video encoder settings used when re-encoding video segments (default: :class:`VideoEncoderConfig()`).
+        camera_encoder_config: Video encoder settings used when re-encoding video segments
+            (``None`` uses :func:`~lerobot.datasets.video_utils.camera_encoder_defaults`).
     """
     if not episode_indices:
         raise ValueError("No episodes to delete")
@@ -165,7 +171,8 @@ def split_dataset(
         splits: Either a dict mapping split names to episode indices, or a dict mapping
                 split names to fractions (must sum to <= 1.0).
         output_dir: Root directory where the split datasets will be stored. If not specified, defaults to $HF_LEROBOT_HOME/repo_id.
-        camera_encoder_config: Video encoder settings used when re-encoding video segments (default: :class:`VideoEncoderConfig()`).
+        camera_encoder_config: Video encoder settings used when re-encoding video segments
+            (``None`` uses :func:`~lerobot.datasets.video_utils.camera_encoder_defaults`).
 
     Examples:
       Split by specific episodes
@@ -598,10 +605,11 @@ def _keep_episodes_from_video_with_av(
             Ranges are half-open intervals: [start_frame, end_frame), where start_frame
             is inclusive and end_frame is exclusive.
         fps: Frame rate of the video.
-        camera_encoder_config: Video encoder settings (default: :class:`VideoEncoderConfig()`).
+        camera_encoder_config: Video encoder settings
+            (``None`` uses :func:`~lerobot.datasets.video_utils.camera_encoder_defaults`).
     """
     if camera_encoder_config is None:
-        camera_encoder_config = VideoEncoderConfig()
+        camera_encoder_config = camera_encoder_defaults()
     from fractions import Fraction
 
     import av
@@ -705,13 +713,14 @@ def _copy_and_reindex_videos(
         src_dataset: Source dataset to copy from
         dst_meta: Destination metadata object
         episode_mapping: Mapping from old episode indices to new indices
-        camera_encoder_config: Video encoder settings used when re-encoding segments (default: :class:`VideoEncoderConfig()`).
+        camera_encoder_config: Video encoder settings used when re-encoding segments
+            (``None`` uses :func:`~lerobot.datasets.video_utils.camera_encoder_defaults`).
 
     Returns:
         dict mapping episode index to its video metadata (chunk_index, file_index, timestamps)
     """
     if camera_encoder_config is None:
-        camera_encoder_config = VideoEncoderConfig()
+        camera_encoder_config = camera_encoder_defaults()
     if src_dataset.meta.episodes is None:
         src_dataset.meta.episodes = load_episodes(src_dataset.meta.root)
 
@@ -1654,7 +1663,8 @@ def convert_image_to_video_dataset(
         dataset: The source LeRobot dataset with images
         output_dir: Root directory where the edited dataset will be stored. If not specified, defaults to $HF_LEROBOT_HOME/repo_id. Equivalent to new_root in EditDatasetConfig.
         repo_id: Edited dataset identifier. Equivalent to new_repo_id in EditDatasetConfig.
-        camera_encoder_config: Video encoder settings (default: :class:`VideoEncoderConfig()`).
+        camera_encoder_config: Video encoder settings
+            (``None`` uses :func:`~lerobot.datasets.video_utils.camera_encoder_defaults`).
         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)
@@ -1664,7 +1674,7 @@ def convert_image_to_video_dataset(
         New LeRobotDataset with images encoded as videos
     """
     if camera_encoder_config is None:
-        camera_encoder_config = VideoEncoderConfig()
+        camera_encoder_config = camera_encoder_defaults()
 
     # Check that it's an image dataset
     if len(dataset.meta.video_keys) > 0:

src/lerobot/datasets/dataset_writer.py

@@ -53,6 +53,7 @@ from .utils import (
 from .video_utils import (
     StreamingVideoEncoder,
     VideoEncoderConfig,
+    camera_encoder_defaults,
     concatenate_video_files,
     encode_video_frames,
     get_video_duration_in_s,
@@ -95,7 +96,7 @@ class DatasetWriter:
         self,
         meta: LeRobotDatasetMetadata,
         root: Path,
-        camera_encoder_config: VideoEncoderConfig,
+        camera_encoder_config: VideoEncoderConfig | None,
         encoder_threads: int | None,
         batch_encoding_size: int,
         streaming_encoder: StreamingVideoEncoder | None = None,
@@ -108,6 +109,7 @@ class DatasetWriter:
                 settings, and episode persistence).
             root: Local dataset root directory.
             camera_encoder_config: Video encoder settings applied to all cameras.
+                ``None`` uses :func:`~lerobot.datasets.video_utils.camera_encoder_defaults`.
             encoder_threads: Number of encoder threads (global). ``None``
                 lets the codec decide.
             batch_encoding_size: Number of episodes to accumulate before
@@ -118,7 +120,7 @@ class DatasetWriter:
         """
         self._meta = meta
         self._root = root
-        self._camera_encoder_config = camera_encoder_config
+        self._camera_encoder_config = camera_encoder_config or camera_encoder_defaults()
         self._encoder_threads = encoder_threads
         self._batch_encoding_size = batch_encoding_size
         self._streaming_encoder = streaming_encoder

src/lerobot/datasets/lerobot_dataset.py

@@ -178,8 +178,8 @@ class LeRobotDataset(torch.utils.data.Dataset):
             batch_encoding_size (int, optional): Number of episodes to accumulate before batch encoding videos.
                 Set to 1 for immediate encoding (default), or higher for batched encoding. Defaults to 1.
             camera_encoder_config (VideoEncoderConfig | None, optional): Video encoder settings for cameras
-                (codec, quality, etc.). Defaults to
-                :class:`~lerobot.datasets.video_utils.VideoEncoderConfig` defaults when ``None``.
+                (codec, quality, etc.). When ``None``, :func:`~lerobot.datasets.video_utils.camera_encoder_defaults`
+                is used by the writer.
             encoder_threads (int | None, optional): Number of encoder threads (global). ``None`` lets the
                 codec decide.
             streaming_encoding (bool, optional): If True, encode video frames in real-time during capture
@@ -204,9 +204,6 @@ class LeRobotDataset(torch.utils.data.Dataset):
         self._video_backend = video_backend if video_backend else get_safe_default_video_backend()
         self._return_uint8 = return_uint8
         self._batch_encoding_size = batch_encoding_size
-        if camera_encoder_config is None:
-            camera_encoder_config = VideoEncoderConfig()
-        self._camera_encoder_config = camera_encoder_config
         self._encoder_threads = encoder_threads
 
         if self._requested_root is not None:
@@ -253,15 +250,15 @@ class LeRobotDataset(torch.utils.data.Dataset):
             if streaming_encoding and len(self.meta.video_keys) > 0:
                 streaming_enc = self._build_streaming_encoder(
                     self.meta.fps,
-                    self._camera_encoder_config,
-                    self._encoder_threads,
+                    camera_encoder_config,
                     encoder_queue_maxsize,
+                    encoder_threads,
                 )
             self.writer = DatasetWriter(
                 meta=self.meta,
                 root=self.root,
-                camera_encoder_config=self._camera_encoder_config,
-                encoder_threads=self._encoder_threads,
+                camera_encoder_config=camera_encoder_config,
+                encoder_threads=encoder_threads,
                 batch_encoding_size=batch_encoding_size,
                 streaming_encoder=streaming_enc,
                 initial_frames=self.meta.total_frames,
@@ -302,15 +299,15 @@ class LeRobotDataset(torch.utils.data.Dataset):
     @staticmethod
     def _build_streaming_encoder(
         fps: int,
-        camera_encoder_config: VideoEncoderConfig,
-        encoder_threads: int | None,
+        camera_encoder_config: VideoEncoderConfig | None,
         encoder_queue_maxsize: int,
+        encoder_threads: int | None,
     ) -> StreamingVideoEncoder:
         return StreamingVideoEncoder(
             fps=fps,
             camera_encoder_config=camera_encoder_config,
-            encoder_threads=encoder_threads,
             queue_maxsize=encoder_queue_maxsize,
+            encoder_threads=encoder_threads,
         )
 
     # ── Metadata properties ───────────────────────────────────────────
@@ -656,9 +653,8 @@ class LeRobotDataset(torch.utils.data.Dataset):
             video_backend: Video decoding backend (used when reading back).
             batch_encoding_size: Number of episodes to accumulate before
                 batch-encoding videos. ``1`` means encode immediately.
-            camera_encoder_config: Video encoder settings for cameras; defaults
-                match :class:`~lerobot.datasets.video_utils.VideoEncoderConfig`
-                when ``None``.
+            camera_encoder_config: Video encoder settings for cameras (codec, quality, etc.).
+                When ``None``, :func:`~lerobot.datasets.video_utils.camera_encoder_defaults` is used.
             encoder_threads: Number of encoder threads (global). ``None``
                 lets the codec decide.
             metadata_buffer_size: Number of episode metadata records to buffer
@@ -671,8 +667,6 @@ class LeRobotDataset(torch.utils.data.Dataset):
         Returns:
             A new :class:`LeRobotDataset` in write mode.
         """
-        if camera_encoder_config is None:
-            camera_encoder_config = VideoEncoderConfig()
         obj = cls.__new__(cls)
         obj.meta = LeRobotDatasetMetadata.create(
             repo_id=repo_id,
@@ -696,7 +690,6 @@ class LeRobotDataset(torch.utils.data.Dataset):
         obj._video_backend = video_backend if video_backend is not None else get_safe_default_video_backend()
         obj._return_uint8 = False
         obj._batch_encoding_size = batch_encoding_size
-        obj._camera_encoder_config = camera_encoder_config
         obj._encoder_threads = encoder_threads
 
         # Reader is lazily created on first access (write-only mode)
@@ -705,7 +698,7 @@ class LeRobotDataset(torch.utils.data.Dataset):
         streaming_enc = None
         if streaming_encoding and len(obj.meta.video_keys) > 0:
             streaming_enc = cls._build_streaming_encoder(
-                fps, camera_encoder_config, encoder_threads, encoder_queue_maxsize
+                fps, camera_encoder_config, encoder_queue_maxsize, encoder_threads
             )
         obj.writer = DatasetWriter(
             meta=obj.meta,
@@ -761,9 +754,8 @@ class LeRobotDataset(torch.utils.data.Dataset):
             video_backend: Video decoding backend for reading back data.
             batch_encoding_size: Number of episodes to accumulate before
                 batch-encoding videos.
-            camera_encoder_config: Video encoder settings for cameras; defaults
-                match :class:`~lerobot.datasets.video_utils.VideoEncoderConfig`
-                when ``None``.
+            camera_encoder_config: Video encoder settings for cameras (codec, quality, etc.).
+                When ``None``, :func:`~lerobot.datasets.video_utils.camera_encoder_defaults` is used.
             encoder_threads: Number of encoder threads (global). ``None``
                 lets the codec decide.
             image_writer_processes: Subprocesses for async image writing.
@@ -801,9 +793,6 @@ class LeRobotDataset(torch.utils.data.Dataset):
             obj.repo_id, obj._requested_root, obj.revision, force_cache_sync=force_cache_sync
         )
 
-        if camera_encoder_config is None:
-            camera_encoder_config = VideoEncoderConfig()
-        obj._camera_encoder_config = camera_encoder_config
         obj._encoder_threads = encoder_threads
         obj.root = obj.meta.root
 
@@ -813,7 +802,7 @@ class LeRobotDataset(torch.utils.data.Dataset):
         streaming_enc = None
         if streaming_encoding and len(obj.meta.video_keys) > 0:
             streaming_enc = cls._build_streaming_encoder(
-                obj.meta.fps, camera_encoder_config, encoder_threads, encoder_queue_maxsize
+                obj.meta.fps, camera_encoder_config, encoder_queue_maxsize, encoder_threads
             )
         obj.writer = DatasetWriter(
             meta=obj.meta,

src/lerobot/datasets/pyav_utils.py

@@ -28,7 +28,7 @@ from typing import TYPE_CHECKING, Any
 import av
 
 if TYPE_CHECKING:
-    from lerobot.datasets.video_utils import VideoEncoderConfig
+    from .video_utils import VideoEncoderConfig
 
 logger = logging.getLogger(__name__)
 
@@ -177,10 +177,6 @@ def check_video_encoder_config_pyav(config: VideoEncoderConfig) -> None:
     vcodec = config.vcodec
     options = _get_codec_options_by_name(vcodec)
     if not options:
-        logger.warning(
-            "Codec %r is not available in the bundled FFmpeg build; ",
-            vcodec,
-        )
-        return
+        raise ValueError(f"Codec {vcodec!r} is not available in the bundled FFmpeg build")
     _check_pixel_format(config.vcodec, config.pix_fmt)
     _check_codec_options(config.vcodec, config.get_codec_options(), config)

src/lerobot/datasets/video_utils.py

@@ -37,17 +37,18 @@ import torchvision
 from datasets.features.features import register_feature
 from PIL import Image
 
-from lerobot.datasets.pyav_utils import (
+from lerobot.utils.import_utils import get_safe_default_video_backend
+
+from .pyav_utils import (
     check_video_encoder_config_pyav,
     detect_available_encoders_pyav,
 )
-from lerobot.utils.import_utils import get_safe_default_video_backend
 
 logger = logging.getLogger(__name__)
 
 # List of hardware encoders to probe for auto-selection. Availability depends on the platform and FFmpeg build.
 # Determines the order of preference for auto-selection when vcodec="auto" is used.
-HW_ENCODERS = [
+HW_VIDEO_CODECS = [
     "h264_videotoolbox",  # macOS
     "hevc_videotoolbox",  # macOS
     "h264_nvenc",  # NVIDIA GPU
@@ -56,7 +57,7 @@ HW_ENCODERS = [
     "h264_qsv",  # Intel Quick Sync
 ]
 
-VALID_VIDEO_CODECS = {"h264", "hevc", "libsvtav1", "auto"} | set(HW_ENCODERS)
+VALID_VIDEO_CODECS = {"h264", "hevc", "libsvtav1", "auto"} | set(HW_VIDEO_CODECS)
 
 LIBSVTAV1_DEFAULT_PRESET: int = 12
 
@@ -116,33 +117,33 @@ class VideoEncoderConfig:
             check_video_encoder_config_pyav(self)
 
     def resolve_vcodec(self) -> None:
-        """Validate vcodec and resolve 'auto' to best available HW encoder, fallback to libsvtav1.
+        """Check ``vcodec`` and, when it is ``"auto"``, pick a concrete encoder.
 
-        Any explicitly-requested codec that isn't in the local FFmpeg build is
-        also silently rewritten to ``libsvtav1`` so encoding never hard-fails on
-        a host missing the requested encoder.
+        For ``"auto"``, the first hardware encoder in the preference list that FFmpeg
+        exposes is chosen; if none are available, ``libsvtav1`` is used. If the
+        resolved codec (explicit or after auto-selection) is not present in the
+        local FFmpeg build, raises ``ValueError``.
         """
         if self.vcodec not in VALID_VIDEO_CODECS:
             raise ValueError(f"Invalid vcodec '{self.vcodec}'. Must be one of: {sorted(VALID_VIDEO_CODECS)}")
         if self.vcodec == "auto":
-            available = self.detect_available_encoders(HW_ENCODERS)
-            for encoder in HW_ENCODERS:
+            available = self.detect_available_encoders(HW_VIDEO_CODECS)
+            for encoder in HW_VIDEO_CODECS:
                 if encoder in available:
                     logger.info(f"Auto-selected video codec: {encoder}")
                     self.vcodec = encoder
                     return
-            logger.info("No hardware encoder available, falling back to software encoder 'libsvtav1'")
+            logger.warning("No hardware encoder available, falling back to software encoder 'libsvtav1'")
             self.vcodec = "libsvtav1"
 
         if self.detect_available_encoders(self.vcodec):
             logger.info(f"Using video codec: {self.vcodec}")
-            self.vcodec = self.vcodec
             return
         raise ValueError(f"Unsupported video codec: {self.vcodec} with video backend {self.video_backend}")
 
     def get_codec_options(
         self, encoder_threads: int | None = None, as_strings: bool = False
-    ) -> dict[str, str]:
+    ) -> dict[str, Any]:
         """Translate the tuning fields to codec-specific FFmpeg options.
 
         ``VideoEncoderConfig.extra_options`` are merged last but never override a structured field.
@@ -498,7 +499,7 @@ def encode_video_frames(
 ) -> None:
     """More info on ffmpeg arguments tuning on `benchmark/video/README.md`"""
     if camera_encoder_config is None:
-        camera_encoder_config = VideoEncoderConfig()
+        camera_encoder_config = camera_encoder_defaults()
     vcodec = camera_encoder_config.vcodec
     pix_fmt = camera_encoder_config.pix_fmt
 
@@ -794,22 +795,21 @@ class StreamingVideoEncoder:
         self,
         fps: int,
         camera_encoder_config: VideoEncoderConfig | None = None,
-        encoder_threads: int | None = None,
-        *,
         queue_maxsize: int = 30,
+        encoder_threads: int | None = None,
     ):
         """
         Args:
             fps: Frames per second for the output videos.
             camera_encoder_config: Video encoder settings applied to all cameras.
-                When ``None``, :class:`VideoEncoderConfig` defaults are used.
+                When ``None``, :func:`camera_encoder_defaults` is used.
             encoder_threads: Number of encoder threads (global setting).
                 ``None`` lets the codec decide.
             queue_maxsize: Max frames to buffer per camera before
                 back-pressure drops frames.
         """
         self.fps = fps
-        self._camera_encoder_config = camera_encoder_config or VideoEncoderConfig()
+        self._camera_encoder_config = camera_encoder_config or camera_encoder_defaults()
         self._encoder_threads = encoder_threads
         self.queue_maxsize = queue_maxsize
 

src/lerobot/rollout/context.py

@@ -332,7 +332,7 @@ def build_rollout_context(
                 cfg.dataset.repo_id,
                 root=cfg.dataset.root,
                 batch_encoding_size=cfg.dataset.video_encoding_batch_size,
-                vcodec=cfg.dataset.vcodec,
+                camera_encoder_config=cfg.dataset.camera_encoder_config,
                 streaming_encoding=cfg.dataset.streaming_encoding,
                 encoder_queue_maxsize=cfg.dataset.encoder_queue_maxsize,
                 encoder_threads=cfg.dataset.encoder_threads,
@@ -367,7 +367,7 @@ def build_rollout_context(
                 image_writer_threads=cfg.dataset.num_image_writer_threads_per_camera
                 * len(robot.cameras if hasattr(robot, "cameras") else []),
                 batch_encoding_size=cfg.dataset.video_encoding_batch_size,
-                vcodec=cfg.dataset.vcodec,
+                camera_encoder_config=cfg.dataset.camera_encoder_config,
                 streaming_encoding=cfg.dataset.streaming_encoding,
                 encoder_queue_maxsize=cfg.dataset.encoder_queue_maxsize,
                 encoder_threads=cfg.dataset.encoder_threads,

tests/datasets/test_video_encoding.py

@@ -298,7 +298,7 @@ class TestEncoderDetection:
 
     @require_videotoolbox
     def test_auto_picks_videotoolbox_when_available(self):
-        """``h264_videotoolbox`` sits at the top of ``HW_ENCODERS`` so it wins when present."""
+        """``h264_videotoolbox`` sits at the top of ``HW_VIDEO_CODECS`` so it wins when present."""
         cfg = VideoEncoderConfig(vcodec="auto")
         assert cfg.vcodec == "h264_videotoolbox"
 
@@ -312,7 +312,7 @@ class TestEncoderDetection:
         assert "h264_nvenc" in VALID_VIDEO_CODECS
 
 
-ARTIFACTS = Path(__file__).parent.parent / "fixtures" / "artifacts" / "videos"
+TEST_ARTIFACTS_DIR = Path(__file__).parent.parent / "artifacts" / "encoded_videos"
 
 # Default video feature set used by persistence tests.
 VIDEO_FEATURES = {
@@ -361,7 +361,7 @@ def _add_frames(dataset: LeRobotDataset, num_frames: int) -> None:
 
 class TestGetVideoInfo:
     def test_returns_all_stream_fields(self):
-        info = get_video_info(ARTIFACTS / "clip_4frames.mp4")
+        info = get_video_info(TEST_ARTIFACTS_DIR / "clip_4frames.mp4")
 
         assert info["video.height"] == 64
         assert info["video.width"] == 96
@@ -378,7 +378,7 @@ class TestGetVideoInfo:
     def test_merges_encoder_config_as_video_prefixed_entries(self):
         cfg = VideoEncoderConfig(vcodec="libsvtav1", g=2, crf=30, preset=12)
 
-        info = get_video_info(ARTIFACTS / "clip_4frames.mp4", camera_encoder_config=cfg)
+        info = get_video_info(TEST_ARTIFACTS_DIR / "clip_4frames.mp4", camera_encoder_config=cfg)
 
         assert info["video.g"] == 2
         assert info["video.crf"] == 30
@@ -391,7 +391,7 @@ class TestGetVideoInfo:
     def test_stream_derived_keys_take_precedence_over_config(self):
         cfg = VideoEncoderConfig(vcodec="libsvtav1", pix_fmt="yuv420p")
 
-        info = get_video_info(ARTIFACTS / "clip_4frames.mp4", camera_encoder_config=cfg)
+        info = get_video_info(TEST_ARTIFACTS_DIR / "clip_4frames.mp4", camera_encoder_config=cfg)
 
         assert info["video.codec"]  # populated from stream, not from config's vcodec
         assert info["video.pix_fmt"] == "yuv420p"
@@ -478,7 +478,9 @@ class TestConcatenateVideoFiles:
     def test_two_clips_frame_count(self, tmp_path):
         """Output frame count equals the sum of the two input frame counts."""
         out = tmp_path / "out.mp4"
-        concatenate_video_files([ARTIFACTS / "clip_6frames.mp4", ARTIFACTS / "clip_4frames.mp4"], out)
+        concatenate_video_files(
+            [TEST_ARTIFACTS_DIR / "clip_6frames.mp4", TEST_ARTIFACTS_DIR / "clip_4frames.mp4"], out
+        )
 
         with av.open(str(out)) as container:
             total = sum(1 for _ in container.decode(video=0))
@@ -486,7 +488,7 @@ class TestConcatenateVideoFiles:
 
     def test_three_clips_frame_count(self, tmp_path):
         out = tmp_path / "out.mp4"
-        clip = ARTIFACTS / "clip_5frames.mp4"
+        clip = TEST_ARTIFACTS_DIR / "clip_5frames.mp4"
         concatenate_video_files([clip, clip, clip], out)
 
         with av.open(str(out)) as container:
@@ -497,7 +499,9 @@ class TestConcatenateVideoFiles:
     def test_geometry_preserved(self, tmp_path):
         """Output resolution, fps, codec and pixel format must match the inputs."""
         out = tmp_path / "out.mp4"
-        concatenate_video_files([ARTIFACTS / "clip_4frames.mp4", ARTIFACTS / "clip_4frames.mp4"], out)
+        concatenate_video_files(
+            [TEST_ARTIFACTS_DIR / "clip_4frames.mp4", TEST_ARTIFACTS_DIR / "clip_4frames.mp4"], out
+        )
 
         info = get_video_info(out)
         assert info["video.height"] == 64
@@ -509,7 +513,7 @@ class TestConcatenateVideoFiles:
     def test_compatibility_check_raises_on_different_codec(self, tmp_path):
         with pytest.raises(ValueError):
             concatenate_video_files(
-                [ARTIFACTS / "clip_4frames.mp4", ARTIFACTS / "clip_h264.mp4"],
+                [TEST_ARTIFACTS_DIR / "clip_4frames.mp4", TEST_ARTIFACTS_DIR / "clip_h264.mp4"],
                 tmp_path / "out.mp4",
                 compatibility_check=True,
             )
@@ -517,7 +521,7 @@ class TestConcatenateVideoFiles:
     def test_compatibility_check_raises_on_different_resolution(self, tmp_path):
         with pytest.raises(ValueError):
             concatenate_video_files(
-                [ARTIFACTS / "clip_4frames.mp4", ARTIFACTS / "clip_32x48.mp4"],
+                [TEST_ARTIFACTS_DIR / "clip_4frames.mp4", TEST_ARTIFACTS_DIR / "clip_32x48.mp4"],
                 tmp_path / "out.mp4",
                 compatibility_check=True,
             )