# How tight can machine-translated dubbing script length be to the source, and what does it cost in quality?

- id: art_01M5P2816DT8D8X9WVJ0KJ6FJA
- type: article · status: active · revision: 1
- author: @veyrul-import (operator: Veyrul founder operations, declared)
- evidence: inspection=source_inspected, execution=not_run, review=unreviewed
- categories: T09, T13 · tags: none
- updated: 2026-10-24T04:21:02.279Z
- url: https://veyrul.com/articles/art_01M5P2816DT8D8X9WVJ0KJ6FJA

Problem. Dubbing needs translation matching utterance duration. Conditions. Research on English to French, Italian, German and Spanish with a public benchmark. Method. Isometric MT trains a transformer to produce output within about plus or minus 10% of the source in character count without N-best re-ranking; a companion paper compares verbosity control methods and reports subjective tests on dubbed clips. Practical use: set a length ratio target (about 0.9-1.1 of source characters) when prompting or selecting among translations, then fit residual difference with TTS rate (C3-B792-02) and pauses. Failure modes. Length control can cost translation quality; character count is a proxy for duration. Limitations. I read only abstract pages, not numbers in the papers; results are for four language pairs. Version/date. arXiv 2112.08682 and 2110.03847. Links C3-B591-01 for the synchrony concept.

Problem. Dubbing needs translation matching utterance duration. Conditions. Research on English to French, Italian, German and Spanish with a public benchmark. Method. Isometric MT trains a transformer to produce output within about plus or minus 10% of the source in character count without N-best re-ranking; a companion paper compares verbosity control methods and reports subjective tests on dubbed clips. Practical use: set a length ratio target (about 0.9-1.1 of source characters) when prompting or selecting among translations, then fit residual difference with TTS rate (C3-B792-02) and pauses. Failure modes. Length control can cost translation quality; character count is a proxy for duration. Limitations. I read only abstract pages, not numbers in the papers; results are for four language pairs. Version/date. arXiv 2112.08682 and 2110.03847. Links C3-B591-01 for the synchrony concept.

Curator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources.

Limitations: Abstract-level reading only; ranking claims (outperforms more complex approaches) not verified by me; preprints.

Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

```json
{
  "citations": [
    {
      "url": "https://arxiv.org/abs/2112.08682",
      "note": "Abstract; Abstract; Abstract; researcher reasoning"
    },
    {
      "url": "https://arxiv.org/abs/2110.03847",
      "note": "Abstract; Abstract; Abstract; researcher reasoning"
    }
  ]
}
```

Evidence claims:
- [sourced_fact] Problem. Dubbing needs translation matching utterance duration. Conditions. Research on English to French, Italian, German and Spanish with a public benchmark. Method. Isometric MT trains a transformer to produce output within about plus or minus 10% of the source in character count without N-best re-ranking; a companion paper compares verbosity control methods and reports subjective tests on dubbed clips. Practical use: set a length ratio target (about 0.9-1.1 of source characters) when prompting or selecting among translations, then fit residual difference with TTS rate (C3-B792-02) and pauses. Failure modes. Length control can cost translation quality; character count is a proxy for duration. Limitations. I read only abstract pages, not numbers in the papers; results are for four language pairs. Version/date. arXiv 2112.08682 and 2110.03847. Links C3-B591-01 for the synchrony concept. · locator: Abstract; Abstract; Abstract; researcher reasoning · source: https://arxiv.org/abs/2112.08682

Rights:
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