Safe Area / Title-Safe Overlay Calculator

Inspectable records

Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

Area

Audio, Music, Photography & Color

Tranche

tranche-4

Evidence ID

t4-296

Ledger rows

1

No ledger note is attached.

Review findings

Under the stated centered-frame interpretation, the formulas are standard legacy broadcast conventions: rectangle width = frame width × percentage, rectangle height = frame height × percentage, and each margin = (frame dimension − safe dimension) ÷ 2. These conventions are not a current universal broadcast compliance specification. The label should not imply that an overlay generated by this calculator satisfies all modern broadcaster, platform, or display requirements.

Formula and scope findings

• The 90% and 80% values are correct only when interpreted as the retained width and height of centered rectangles; the specification does not explicitly state whether the percentages apply independently to both dimensions or to area.
• Pixel-coordinate rounding is unspecified. Resolutions such as 720x576 produce fractional boundaries (for example, 28.8 pixels), so the integer-pixel rendering rule must be defined.
• Coordinate semantics are unspecified: right/bottom could be inclusive pixel indices or exclusive geometric boundaries.

Unit assumptions

• Resolution width and height are positive integers measured in display pixels.
• Safe-area percentages are dimensionless values expressed from 0 to 100, with 90 meaning 0.90 and 80 meaning 0.80.
• The retained percentage applies independently to both width and height, centered in the full frame.
• Test outputs treat right and bottom as exclusive geometric boundaries; no pixel rounding is applied.
• No physical units, DPI, aspect-ratio conversion, or device-pixel-ratio conversion is involved.

Boundary hardening

BREAK_CLAIMED · SELF_FLAGGED

The specification does not define validation for percentages outside 0-100, integer-resolution requirements, floating-point limits, or inclusive versus half-open pixel endpoints. A title percentage above 100% therefore produces an out-of-frame rectangle unless rejected, and extreme dimensions cause subpixel margin collapse and potentially inconsistent floating-point results.

Errata and corrections

No applied erratum is attached to this unique-name record.

Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

{
  "inputs": {
    "resolution": {
      "width_px": 1920,
      "height_px": 1080
    },
    "safe_area_percentages": {
      "action": 90,
      "title": 80
    }
  },
  "expected_outputs": {
    "action_safe": {
      "left": 96,
      "top": 54,
      "right": 1824,
      "bottom": 1026
    },
    "title_safe": {
      "left": 192,
      "top": 108,
      "right": 1728,
      "bottom": 972
    }
  },
  "working": "Action width = 1920 × 0.90 = 1728; action height = 1080 × 0.90 = 972; horizontal margin = (1920 − 1728) ÷ 2 = 96; vertical margin = (1080 − 972) ÷ 2 = 54; action rectangle = (96, 54) to (96 + 1728, 54 + 972) = (96, 54) to (1824, 1026). Title width = 1920 × 0.80 = 1536; title height = 1080 × 0.80 = 864; horizontal margin = (1920 − 1536) ÷ 2 = 192; vertical margin = (1080 − 864) ÷ 2 = 108; title rectangle = (192, 108) to (192 + 1536, 108 + 864) = (192, 108) to (1728, 972)."
}

Related workflows

Sources and evidence

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

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