lacing.adapters.webvtt#

WebVTT (W3C TimedText) adapter.

WebVTT is a flat caption format: one stream of cues, no tier hierarchy. Cues have a start time, an end time, optional id and settings, and a payload (text with limited inline markup).

We map cues to a single tier named cues (override with tier=). Each cue becomes one Annotation whose body holds:

{“text”: str, “id”: str | None, “settings”: dict[str, str]}

Lossy fields on dump:

Provenance, confidence, schema URIs, and tier metadata are dropped. Only the text, id (if present), and settings are emitted.

Time discipline:

WebVTT timestamps are HH:MM:SS.mmm or MM:SS.mmm (with milliseconds). Parsing goes through string fractions to avoid float ingestion. Default rate is 1000 (millisecond precision); override with rate= if your project uses a different canonical rate.

Spec: https://www.w3.org/TR/webvtt1/

Functions

dump(store[, target, tier])

Write annotations as WebVTT.

load(source, *[, rate, asset_id, ...])

Parse a WebVTT file or string/bytes into a MemoryStore.
lacing.adapters.webvtt.dump(store, target=None, *, tier=None, **_kwargs)[source]#

Write annotations as WebVTT.

Parameters:

  • store (IntervalAnnotationStore) – Source store. Only annotations from tier (default: all tiers) with a MediaRef interval are emitted, sorted by start.

  • target (str | PathLike | None) – Output path. If None, returns bytes (UTF-8).

  • tier (str | None) – Restrict export to this tier. None = export all annotations.

Return type:

bytes | None

lacing.adapters.webvtt.load(source, *, rate=1000, asset_id='webvtt:unspecified', attribution='anonymous', tier='cues', **_kwargs)[source]#

Parse a WebVTT file or string/bytes into a MemoryStore.

Return type:

IntervalAnnotationStore