# Overtone releases tool to cut captions for any screen shape

Digest AI · Agents & Tools · published 2026-10-29T17:48:17Z

Canonical: https://digestai.news/story/overtone-releases-tool-to-cut-captions-for-any-screen-shape

## Summary

Overtone is a new open-source tool that transcribes, corrects, and formats video captions for multiple screen shapes from a single file. It stores each spoken word once with its timestamp and speaker, then generates separate caption cuts for different aspect ratios, such as 16:9 for desktop and 9:16 for social media. The tool uses a CLI to process subtitles, audio, or video, and includes a video.js plugin for playback.

The system combines multiple speech engines, including OpenAI and Azure AI Speech, to improve accuracy. It uses an LLM to correct misheard words and names based on context, while ensuring timestamps remain accurate by relying on the speech engines for timing. Benchmarks show Overtone achieves a 5.3% word error rate, outperforming individual engines like gpt-transcribe (6.2%) and Azure Speech (7.7%). It also significantly reduces line breaks ending on weak words, with only 0.3% of breaks ending on words like "the" or "of", compared to 28.8% for standard line-filling methods.

The tool is designed for offline use without API keys for recutting existing subtitles, though full transcription requires provider keys. It supports languages including English, Dutch, German, French, Spanish, Italian, and Portuguese, with specific rules for line breaking and number handling. The project is public, with full method details and caveats available in its documentation.

## Key points

- Overtone cuts captions for 16:9 and 9:16 screens from one file, storing words once.
- Benchmarks show 5.3% word error rate, better than gpt-transcribe's 6.2% and Azure's 7.7%.
- Only 0.3% of line breaks end on weak words, compared to 28.8% for standard methods.

## Why it matters

Solves a common pain point for video creators needing captions for both desktop and mobile. Improves accessibility and viewer experience by ensuring clean, readable captions across all devices without manual reformatting.

## Sources

1. [Show HN: Overtone – Transcribe, correct and cut captions for any screen shape](https://github.com/lonthq/overtone-captions) (github.com, 2026-10-29, primary source)

## Cite

Digest AI, "Overtone releases tool to cut captions for any screen shape", 29 October 2026, https://digestai.news/story/overtone-releases-tool-to-cut-captions-for-any-screen-shape

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