comma.ai Video Compression Challenge
Ongoing video-compression research, with three submissions that have appeared on comma.ai’s leaderboard.
I’m working on comma.ai’s lossy video compression challenge: making a driving video smaller while preserving what the challenge’s segmentation and motion-estimation models see. That means testing both the file size and the effect of compression on those models.
I use comma-lab for experiments, decoders, evaluation tools, and research records. tac contains reusable training, compression, and validation code. I develop across Apple Silicon and Linux GPU environments and check submission archives with the challenge’s evaluator.
Leaderboard submissions
My submissions #107, #110, and #140 have all appeared on the official leaderboard:
- #107, Apogee: an HNeRV-based representation with a deterministic decoder.
- #110: per-frame-pair corrections selected against both segmentation and pose distortion, stored with fixed Huffman coding.
- #140: semantic edits and pose compensation, combined with improvements to lossless coding and the archive format.
These submissions build on credited public work. #110 uses #101’s HNeRV representation; #140 builds on the learned renderer and pose components in #130 and #135, including #133’s contributions. The pull requests describe my optimization, selection, coding, and validation work.
For a more visual introduction to related research, The Witness Machine is an interactive notebook about allocating compression error around what a perception model needs. Its demonstrations are separate from official challenge scores.
The research is ongoing. These leaderboard results apply to the challenge’s fixed video and evaluators.
Public submission reports · 600 samples each
What goes into the score?
The challenge charges for file size and for changes in two perception models’ outputs. Lower is better.
- Archive size
- 180,002 B
- Original video
- 37,545,489 B
- Score, approximately
- 0.1480
100 × SegNet distortion + √(10 × PoseNet distortion) + 25 × archive/original size. Recomputed from the rounded components in PR #140. Evaluation: CUDA · Tesla T4. Hardware differs between reports, and these values are not a live ranking.
A frame and the model’s segmentation


This reference pair comes from Witness Machine. Its cached segmentation was produced on macOS CPU and is a visual diagnostic, separate from the submission reports above. It does not show a reconstruction from any of these three archives.