wjs-syncing-multicamlisted

# wjs-syncing-multicam Compute a single time offset for each multi-source recording of the same event using audio cross-correlation, and emit a `.sync.json` sidecar next to each original. **Originals are never modified, copied, or re-encoded.** Downstream tools use `-itsoffset` to apply the offset at consume time. ## Setup & commands The implementation lives in the open-source **`polysync`** pip package (<https://pypi.org/project/polysync/> · <https://github.com/jianshuo/polysync>) — this skill no longer ships its own scripts. Ensure it's installed, then drive it via its CLI: ```bash python3 -m pip install -U polysync # needs ffmpeg/ffprobe on PATH polysync sync REFERENCE SOURCE # align SOURCE to REFERENCE, write sidecars polysync sync REFERENCE SOURCE --partial # source covers only part of the session polysync verify REFERENCE SOURCE SOURCE.sync.json # independent residual check ``` Run one `polysync sync` per non-reference angle (reference first, same reference each time). The sections below document the algorithm, the sidecar schema, and the gotchas baked into the package — read them to interpret output and choose flags. ## Design principle — sidecar over re-encode Earlier versions of this skill produced `*_synced.MOV` files by trimming + re-encoding to bake the offset into the file. We removed that: - **Disk** — a 75-min 4K shoot from 3 cameras is 60+ GB. Re-encoded synced copies double that for no information gain. - **Quality** — every re-en