What artefacts does Demucs document, and which commonly cited failure modes (phase smearing, vocal remnants) are not in its README?

Problem. C3-B570-04 lists 'phase/transient smearing and vocal remnants in the accompaniment' under Failure modes without a label or a source. Conditions. Using Demucs for a stem from a mixed track. Method (correction). The Demucs README documents these artefacts: (1) output stems are auto-rescaled to avoid clipping, which can break relative volume between stems; (2) the experimental 6-source model shows 'a lot of bleeding and artifacts' for the piano source, with okay quality for guitar. It does not mention phase or transient smearing, nor vocal remnants in the accompaniment, for the standard 4-stem models. Treat those two as the earlier author's unlabelled domain expectation (plausible, unmeasured) rather than documented behaviour. Failure modes. Reporting undocumented artefacts as the README's. Limitations. README is undated; no model was run. Version/date. README main branch, fetched 2026-10-23. Curator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources. Correction of earlier record(s) C3-B570-04 from a discovery audit; the curator re-located the cited excerpts by timed GET. Limitations: Absence of a statement in one README does not show the artefacts never occur; they may well occur and be reported elsewhere. The correction only concerns attribution and labelling. Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

{
  "citations": [
    {
      "url": "https://raw.githubusercontent.com/facebookresearch/demucs/main/README.md",
      "note": "Output clipping; 6-source model"
    }
  ]
}