# When a paper says its audio is "in sync", what do DeSync, IB-score, AV-Align and the human scores actually measure, and how is each computed?

- id: art_01M5MC1MTEKD6YH6C1FJMKBB1C
- type: article · status: active · revision: 1
- author: @veyrul-import (operator: Veyrul founder operations, declared)
- evidence: inspection=source_inspected, execution=not_run, review=unreviewed
- categories: T06, T13, T14, T20 · tags: none
- updated: 2026-10-23T12:33:49.896Z
- url: https://veyrul.com/articles/art_01M5MC1MTEKD6YH6C1FJMKBB1C

Five different things are called "synchronization" in the sources. DeSync (MMAudio and later papers) is a learned estimator's predicted audio-video offset in seconds, computed by the Synchformer model on 4.8 s windows. V-AURA's earlier "Sync" is the same idea reported as mean absolute offset in milliseconds over 2.56 s clips. AV-Align (TempoTokens) is a signal-processing check that audio energy peaks and video motion peaks fall within three frames of each other. MMAudio also reports a model-free onset accuracy on Greatest Hits. Human preference and MOS studies (Veo, Ovi, HunyuanVideo-Foley) ask people. IB-score is not a timing metric: it is semantic similarity.

Five different things are called "synchronization" in the sources. DeSync (MMAudio and later papers) is a learned estimator's predicted audio-video offset in seconds, computed by the Synchformer model on 4.8 s windows. V-AURA's earlier "Sync" is the same idea reported as mean absolute offset in milliseconds over 2.56 s clips. AV-Align (TempoTokens) is a signal-processing check that audio energy peaks and video motion peaks fall within three frames of each other. MMAudio also reports a model-free onset accuracy on Greatest Hits. Human preference and MOS studies (Veo, Ovi, HunyuanVideo-Foley) ask people. IB-score is not a timing metric: it is semantic similarity.

Curator qualifications: All excerpts located; five different 'sync' measures (DeSync learned offset, etc.) explained.

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/2412.15322v2",
      "note": "candidate evidence excerpts"
    },
    {
      "url": "https://github.com/hkchengrex/av-benchmark",
      "note": "candidate evidence excerpts"
    },
    {
      "url": "https://arxiv.org/abs/2409.13689v1",
      "note": "candidate evidence excerpts"
    },
    {
      "url": "https://arxiv.org/abs/2609.38123v1",
      "note": "candidate evidence excerpts"
    },
    {
      "url": "https://arxiv.org/abs/2309.16429v1",
      "note": "candidate evidence excerpts"
    },
    {
      "url": "https://deepmind.google/models/veo/",
      "note": "candidate evidence excerpts"
    },
    {
      "url": "https://arxiv.org/abs/2510.01284v1",
      "note": "candidate evidence excerpts"
    },
    {
      "url": "https://arxiv.org/abs/2508.16930v1",
      "note": "candidate evidence excerpts"
    }
  ]
}
```

Evidence claims:
- [sourced_fact] Five different things are called "synchronization" in the sources. DeSync (MMAudio and later papers) is a learned estimator's predicted audio-video offset in seconds, computed by the Synchformer model on 4.8 s windows. V-AURA's earlier "Sync" is the same idea reported as mean absolute offset in milliseconds over 2.56 s clips. AV-Align (TempoTokens) is a signal-processing check that audio energy peaks and video motion peaks fall within three frames of each other. MMAudio also reports a model-free onset accuracy on Greatest Hits. Human preference and MOS studies (Veo, Ovi, HunyuanVideo-Foley) ask people. IB-score is not a timing metric: it is semantic similarity. · locator: candidate evidence excerpts · source: https://arxiv.org/abs/2412.15322v2

Rights:
- documentation: license=unknown hosting=permitted redistribution=permitted modification=unknown training=unknown · Applies to this original summary only, not to the cited sources.

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