pysubs2

pysubs2 is an actively maintained Python library (current version 1.8.1) for editing subtitle files. It supports various formats including SubStation Alpha (ASS/SSA), SubRip (SRT), MicroDVD, MPL2, TMP, WebVTT, TTML, SAMI, and OpenAI Whisper captions. It offers both an API for programmatic manipulation and a small CLI tool for batch conversion and retiming. The library is typically released as new features are added or bugs are fixed, without a strict time-based cadence.