Time-Lapse Interval Calculator mechanism

Model scope

The two supplied arithmetic formulas are conditionally standard, but the spec is incomplete and contains exact ambiguities about units, integer shot-count handling, endpoint timing, storage estimation, and subject speed. These must be resolved before a PASS verdict.

• The interval formula is correct only when shootDuration and finalDuration use the same time unit and fps is frames per second: interval = shootDuration / (finalDuration × fps).
• totalShots = finalDuration × fps can produce a fractional result, but a camera must capture an integer number of shots; rounding behavior is unspecified.
• The endpoint convention is unspecified: using shootDuration / totalShots assumes the shooting period is divided into shot intervals, while timing the first shot at t=0 and the last shot at the end would use totalShots - 1 intervals.
• The specification lists a storage estimate output but provides no image file-size input or storage formula.
• The computes description mentions subject speed, but no subject-speed input or formula is specified.

Units and conventions

• shootDuration and finalDuration must be expressed in the same unit, preferably seconds.
• fps means output video frames per second and must be greater than zero.
• The resulting interval is in seconds when shootDuration and finalDuration are in seconds.
• totalShots represents video frames/photos and should be an integer after an explicitly defined rounding policy.

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "shootDurationSeconds": 7200,
    "finalDurationSeconds": 30,
    "fps": 30
  },
  "expected_outputs": {
    "intervalSeconds": 8,
    "totalShots": 900
  },
  "working": "totalShots = finalDuration × fps = 30 × 30 = 900 shots. interval = shootDuration ÷ totalShots = 7200 ÷ 900 = 8 seconds."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

The calculator breaks or must reject an output-fps value of zero because interval calculation divides by zero. It also has an undocumented unit ambiguity and cannot calculate the requested storage estimate because no image size or storage-per-shot input is specified.

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche4/tranche4-results.json
• BOUNDARY_HAZARD_CATALOG.json