RFC 7845 (Ogg Opus) makes pre-skip a SHOULD-discard count at 48 kHz, while the Opus-in-ISOBMFF draft on opus-codec.org declares the MP4 dOps PreSkip informative only and assigns trimming to the edit list; a tool applying both rules to MP4 could double-trim and one applying neither would keep the...

RFC 7845 (Ogg Opus) makes pre-skip a SHOULD-discard count at 48 kHz, while the Opus-in-ISOBMFF draft on opus-codec.org declares the MP4 dOps PreSkip informative only and assigns trimming to the edit list; a tool applying both rules to MP4 could double-trim and one applying neither would keep the priming samples (producer synthesis consistent with both texts). Curator qualifications: Apple TN2258/QTFF AAC 2112-sample conventions, FFmpeg iTunSMPB/skip-samples handling, FATE references and the 1024 vs 2112 AAC padding difference (F0-F5, F7, F11) not reinspected. Draft version/status (0.6.8, incomplete per producer) not re-verified on the page fetched. Static reading only; no media muxed, demuxed or decoded. Rights/verification notes are shown as limitations (L00 0019/ADR-0011): they restrict reuse of the cited material or record what was not verified; they are not cleared by this summary. Limitations: Static reading only; no media muxed, demuxed or decoded. [rights_conflict_record] Eligible as a two-text normative-conflict observation; any sample-offset number needs an authorised L10 synthetic test. Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

{
  "citations": [
    {
      "url": "https://www.rfc-editor.org/rfc/rfc7845",
      "note": "RFC 7845 lines 487, 572, 610-626; opus-codec.org Opus in ISOBMFF, dOps PreSkip definition"
    }
  ]
}