[shobhitagnihotri69]

Summary

Fixes #743. In hflow.importers.lerobot._transcode_mp4_to_h264, replace custom _split_h264_by_aud with canonical hflow.video.split_annex_b_stream.

Why

_split_h264_by_aud used offset = boundary_index + 5 which stripped the start code (00 00 00 01) and NAL type byte (09) from each access unit, leaving the primary picture type byte dangling at the front of each frame. This produced non-conforming Annex B payloads that failed split_annex_b_stream validation with ValueError: no access-unit delimiter (AUD, NAL type 9) found.

Using the existing, spec-compliant hflow.video.split_annex_b_stream keeps the full AUD intact and produces valid, decodable H.264 access units matching the canonical video convention.

Validation

• Added test_transcode_mp4_to_h264_preserves_aud_and_annex_b_structure in tests/test_lerobot_converter.py.
• uv run pytest tests/test_lerobot_converter.py tests/test_lerobot_workflow.py tests/test_lerobot_export.py (110 passed).
• uv run ruff check (All checks passed).
• uv run ruff format --check (323 files already formatted).
• uv run ty check (All checks passed).

Checklist

• I added or updated outcome-focused tests for changed business logic.
• I updated documentation for changed behavior, flags, formats, or requirements.
• I ran uv run ruff check --fix, uv run ruff format, and uv run ty check.
• I ran the relevant pytest suite.
• I did not add recordings, generated media, credentials, private URLs, or runtime artifacts.
• I preserved stored-data compatibility or documented an explicit version change.

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[greptile-apps]

Confidence Score: 5/5

[Medium impact] The PR appears safe to merge, with the previous finding fully addressed and no new issues found.

Summary

The PR uses split_annex_b_stream to preserve complete AUD markers in transcoded H.264 frames.

• LeRobot video imports keep each AUD with its H.264 frame.

_{Reviews (2) · Last reviewed commit: "test(lerobot): add _requires_system_ffmp..." · Reviewed by Greptile}