Local dataset viewer not compatible with libtorchcodec #3199
Description
Ticket Type
🐛 Bug Report
Environment & System Info
- LeRobot Version: 0.5.1 (autoinstall)
- OS: Ubuntu 24.04 LTS
- Python: 3.12 (Miniconda)
- PyTorch Version: 2.10.0+cu128
- GPU: NVIDIA GeForce RTX 5070 Laptop (Driver 580.126.09)
Description
Simply uploading a lerobot-record dataset using default methods causes the dataset to be unviewable by the dataset visualizer.
- The visualizer UI fails with:
"Something went wrong. Failed to fetch dataset info: 401"(or Error 404). - The CLI utility
lerobot-dataset-vizcrashes with aRuntimeErrorregardinglibtorchcodec.
It appears to be a library mismatch between the environment's FFmpeg/PyTorch version and what torchcodec expects.
Context & Reproduction
The crash occurs immediately after "Logging to Rerun" when the dataloader begins fetching frames.
Command:
lerobot-dataset-viz --repo-id thesimbotbro/eval_PickAndPlace_30Hz_Seth3 --episode-index 0Relevant Logs & Stack Trace
INFO 2026-03-21 23:10:12 aset_viz.py:115 Starting Rerun
[2026-03-22T03:10:12Z INFO re_grpc_server] Listening for gRPC connections on 0.0.0.0:9876.
...
Traceback (most recent call last):
File ".../lerobot/datasets/video_utils.py", line 152, in decode_video_frames
return decode_video_frames_torchcodec(video_path, timestamps, tolerance_s)
...
File ".../torchcodec/_core/ops.py", line 69, in load_torchcodec_shared_libraries
raise RuntimeError(
RuntimeError: Could not load libtorchcodec. Likely causes:
1. FFmpeg is not properly installed in your environment. We support versions 4, 5, 6 and 7.
2. The PyTorch version (2.10.0+cu128) is not compatible with this version of TorchCodec.
3. Another runtime dependency.
[start of libtorchcodec loading traceback]
FFmpeg version 7: Could not load this library: .../libtorchcodec_core7.so
FFmpeg version 6: Could not load this library: .../libtorchcodec_core6.so
FFmpeg version 5: Could not load this library: .../libtorchcodec_core5.so
FFmpeg version 4: Could not load this library: .../libtorchcodec_core4.so
[end of libtorchcodec loading traceback]
Checklist
- I have searched existing tickets to ensure this isn't a duplicate.
- I am using the latest version of the
mainbranch. - I have verified this is not an environment-specific problem.
Additional Info / Workarounds
It seems that torchcodec is unable to find the shared objects for FFmpeg versions 4-7 in the current environment path, or there is a version mismatch with PyTorch 2.10.0+cu128.