Show HN: Overtone – Transcribe, correct and cut captions for any screen shape

Overtone is a captioning tool that stores transcribed words with timestamps in a single file and automatically generates optimized captions for different screen formats (16:9, 9:16, and custom aspect ratios) without requiring API keys or ffmpeg for basic use. The tool includes a CLI for creating caption files from subtitles, audio, or video, and a video.js plugin for displaying the appropriately formatted captions in any player. It improves upon traditional captioning by applying reading rules to keep names and numbers together and avoid ending lines on weak words.