GoKawiilNew open-source tool Overtone cuts video captions separately for each screen aspect ratio
A developer released Overtone, an open-source captioning system that stores transcribed words with timing and speaker data once, then generates separate caption cuts optimized for different screen shapes like 16:9 and 9:16 from a single file. It ships as a CLI for creating or re-cutting caption files from subtitles, audio, or video, plus a video.js player plugin that displays the caption version matching the player's shape. The tool supports offline re-cutting of existing subtitles, and can transcribe audio using OpenAI or Azure APIs, or run fully offline via whisper.cpp and Ollama.
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The project targets a common pain point for creators repurposing horizontal video for vertical social platforms, where traditional captions cut for one aspect ratio often produce awkwardly broken lines or crowd multiple speakers into one caption. By keeping per-shape caption cuts in a single structured file, Overtone could simplify workflows for creators publishing the same footage across formats like YouTube and TikTok. As a freshly shown open-source Show HN project, its adoption and real-world robustness remain unproven.
- Overtone generates aspect-ratio-specific caption cuts (e.g., 16:9 and 9:16) from one source file.
- It offers offline re-cutting of existing subtitles and optional cloud or local (whisper.cpp/Ollama) transcription.
- A video.js plugin displays the caption variant matching the player's screen shape automatically.
Source: github.com, 2026-10-29
Published there as: “Show HN: Overtone – Transcribe, correct and cut captions for any screen shape”
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