FAILURE MAP
← Case archive

FA-78121 / Subtitle cue timing / Open access

Proportional cue splitting: cumulative weight · case 01

Split pieces overlap and the final piece does not end at the cue end.

Verified by executionVariant 1 · 7 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

Boundaries use only the current part weight instead of the running total.

VERIFIED REPAIR

Accumulate the weights before computing each boundary.

Unsuccessful approach: Accumulating raw lengths disagrees with the trimmed total and misplaces later boundaries.

Case contract

Split cue [start,end] into len(parts) consecutive cues. Each part weighs max(1, len(part.strip())). Boundary after part k is start + floor(dur * cumulative_weight_k / total_weight); pieces are contiguous and the last ends at end. Output [s,e,part.strip()].

Why this case matters

Subtitle timing defects shift, hide or overlap captions that viewers depend on for comprehension and accessibility.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(cue, parts):
    start,end=cue
    w=[max(1,len(p.strip())) for p in parts]
    total=sum(w)
    dur=end-start
    out=[]
    acc=0
    prev=start
    for p,x in zip(parts,w):
        acc=x
        b=start+dur*acc//total
        out.append([prev,b,p.strip()])
        prev=b
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: cumulative weight', [[0, 1000], ['ab', 'cd']], [[0, 500, 'ab'], [500, 1000, 'cd']]), ('regression variant: cumulative weight', [[1000, 1007], ['a', 'xyz', 'friend', 'a']], [[1000, 1000, 'a'], [1000, 1002, 'xyz'], [1002, 1006, 'friend'], [1006, 1007, 'a']]), ('partial repair probe: cumulative weight', [[0, 100], ['friend', 'ok ', 'ok ']], [[0, 60, 'friend'], [60, 80, 'ok'], [80, 100, 'ok']]), ('partial repair variant: cumulative weight', [[1000, 1100], [' there ', 'ok ', 'Longer chunk of text']], [[1000, 1018, 'there'], [1018, 1025, 'ok'], [1025, 1100, 'Longer chunk of text']]), ('normal control', [[0, 2500], ['xyz']], [[0, 2500, 'xyz']]), ('normal control', [[1000, 1999], ['friend']], [[1000, 1999, 'friend']]), ('normal control', [[0, 3001], ['a']], [[0, 3001, 'a']])], [('regression: cumulative weight', [[0, 1000], ['a', '']], [[0, 500, 'a'], [500, 1000, '']]), ('regression variant: cumulative weight', [[1000, 1999], ['Longer chunk of text', 'xyz']], [[1000, 1868, 'Longer chunk of text'], [1868, 1999, 'xyz']]), ('partial repair probe: cumulative weight', [[0, 7], [' there ']], [[0, 7, 'there']]), ('partial repair variant: cumulative weight', [[1000, 1999], ['  ']], [[1000, 1999, '']]), ('normal control', [[12345, 15346], ['Hello']], [[12345, 15346, 'Hello']]), ('normal control', [[12345, 13345], ['xyz']], [[12345, 13345, 'xyz']]), ('normal control', [[12345, 13345], ['friend']], [[12345, 13345, 'friend']])], [('regression: cumulative weight', [[0, 7], ['abc', 'de', 'f']], [[0, 3, 'abc'], [3, 5, 'de'], [5, 7, 'f']]), ('regression variant: cumulative weight', [[0, 100], ['friend', 'ok ', 'ok ']], [[0, 60, 'friend'], [60, 80, 'ok'], [80, 100, 'ok']]), ('partial repair probe: cumulative weight', [[0, 3001], ['ok ', ' there ']], [[0, 857, 'ok'], [857, 3001, 'there']]), ('partial repair variant: cumulative weight', [[1000, 4001], ['friend', 'a', ' there ', 'a']], [[1000, 2385, 'friend'], [2385, 2615, 'a'], [2615, 3770, 'there'], [3770, 4001, 'a']]), ('normal control', [[1000, 1007], ['friend']], [[1000, 1007, 'friend']]), ('normal control', [[0, 1000], ['Longer chunk of text']], [[0, 1000, 'Longer chunk of text']]), ('normal control', [[12345, 15346], ['xyz']], [[12345, 15346, 'xyz']])], [('regression: cumulative weight', [[100, 1100], [' x ', 'y']], [[100, 600, 'x'], [600, 1100, 'y']]), ('regression variant: cumulative weight', [[0, 3001], ['ok ', ' there ']], [[0, 857, 'ok'], [857, 3001, 'there']]), ('partial repair probe: cumulative weight', [[1000, 1999], ['ok ', 'Hello']], [[1000, 1285, 'ok'], [1285, 1999, 'Hello']]), ('partial repair variant: cumulative weight', [[0, 7], ['  ', 'ok ', '  ', 'ok ']], [[0, 1, ''], [1, 3, 'ok'], [3, 4, ''], [4, 7, 'ok']]), ('normal control', [[1000, 3500], ['a']], [[1000, 3500, 'a']]), ('normal control', [[12345, 12352], ['a']], [[12345, 12352, 'a']]), ('normal control', [[12345, 12352], ['Longer chunk of text']], [[12345, 12352, 'Longer chunk of text']])], [('regression: cumulative weight', [[0, 7], ['friend', 'Hello', 'ok ']], [[0, 3, 'friend'], [3, 5, 'Hello'], [5, 7, 'ok']]), ('regression variant: cumulative weight', [[1000, 1999], ['ok ', 'Hello']], [[1000, 1285, 'ok'], [1285, 1999, 'Hello']]), ('partial repair probe: cumulative weight', [[1000, 1999], ['ok ', '  ', 'friend', 'ok ']], [[1000, 1181, 'ok'], [1181, 1272, ''], [1272, 1817, 'friend'], [1817, 1999, 'ok']]), ('partial repair variant: cumulative weight', [[1000, 2000], ['ok ', '', '']], [[1000, 1500, 'ok'], [1500, 1750, ''], [1750, 2000, '']]), ('normal control', [[12345, 13345], ['Hello']], [[12345, 13345, 'Hello']]), ('normal control', [[12345, 15346], ['friend']], [[12345, 15346, 'friend']]), ('normal control', [[0, 100], ['Hello']], [[0, 100, 'Hello']])]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
regression: cumulative weight[[0, 500, 'ab'], [500, 500, 'cd']][[0, 500, 'ab'], [500, 1000, 'cd']]Failed
regression variant: cumulative weight[[1000, 1000, 'a'], [1000, 1001, 'xyz'], [1001, 1003, 'friend'], [1003, 1000, 'a']][[1000, 1000, 'a'], [1000, 1002, 'xyz'], [1002, 1006, 'friend'], [1006, 1007, 'a']]Failed
partial repair probe: cumulative weight[[0, 60, 'friend'], [60, 20, 'ok'], [20, 20, 'ok']][[0, 60, 'friend'], [60, 80, 'ok'], [80, 100, 'ok']]Failed
partial repair variant: cumulative weight[[1000, 1018, 'there'], [1018, 1007, 'ok'], [1007, 1074, 'Longer chunk of text']][[1000, 1018, 'there'], [1018, 1025, 'ok'], [1025, 1100, 'Longer chunk of text']]Failed
normal control[[0, 2500, 'xyz']][[0, 2500, 'xyz']]Passed
normal control[[1000, 1999, 'friend']][[1000, 1999, 'friend']]Passed
normal control[[0, 3001, 'a']][[0, 3001, 'a']]Passed

SHA-256 / 713b296f0af1105c7c45fa6425bd2be6f08dead6bfe285427c083253e4afd642

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(cue, parts):
    start,end=cue
    w=[max(1,len(p.strip())) for p in parts]
    total=sum(w)
    dur=end-start
    out=[]
    acc=0
    prev=start
    for p,x in zip(parts,w):
        acc+=len(p)
        b=start+dur*acc//total
        out.append([prev,b,p.strip()])
        prev=b
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: cumulative weight', [[0, 1000], ['ab', 'cd']], [[0, 500, 'ab'], [500, 1000, 'cd']]), ('regression variant: cumulative weight', [[1000, 1007], ['a', 'xyz', 'friend', 'a']], [[1000, 1000, 'a'], [1000, 1002, 'xyz'], [1002, 1006, 'friend'], [1006, 1007, 'a']]), ('partial repair probe: cumulative weight', [[0, 100], ['friend', 'ok ', 'ok ']], [[0, 60, 'friend'], [60, 80, 'ok'], [80, 100, 'ok']]), ('partial repair variant: cumulative weight', [[1000, 1100], [' there ', 'ok ', 'Longer chunk of text']], [[1000, 1018, 'there'], [1018, 1025, 'ok'], [1025, 1100, 'Longer chunk of text']]), ('normal control', [[0, 2500], ['xyz']], [[0, 2500, 'xyz']]), ('normal control', [[1000, 1999], ['friend']], [[1000, 1999, 'friend']]), ('normal control', [[0, 3001], ['a']], [[0, 3001, 'a']])], [('regression: cumulative weight', [[0, 1000], ['a', '']], [[0, 500, 'a'], [500, 1000, '']]), ('regression variant: cumulative weight', [[1000, 1999], ['Longer chunk of text', 'xyz']], [[1000, 1868, 'Longer chunk of text'], [1868, 1999, 'xyz']]), ('partial repair probe: cumulative weight', [[0, 7], [' there ']], [[0, 7, 'there']]), ('partial repair variant: cumulative weight', [[1000, 1999], ['  ']], [[1000, 1999, '']]), ('normal control', [[12345, 15346], ['Hello']], [[12345, 15346, 'Hello']]), ('normal control', [[12345, 13345], ['xyz']], [[12345, 13345, 'xyz']]), ('normal control', [[12345, 13345], ['friend']], [[12345, 13345, 'friend']])], [('regression: cumulative weight', [[0, 7], ['abc', 'de', 'f']], [[0, 3, 'abc'], [3, 5, 'de'], [5, 7, 'f']]), ('regression variant: cumulative weight', [[0, 100], ['friend', 'ok ', 'ok ']], [[0, 60, 'friend'], [60, 80, 'ok'], [80, 100, 'ok']]), ('partial repair probe: cumulative weight', [[0, 3001], ['ok ', ' there ']], [[0, 857, 'ok'], [857, 3001, 'there']]), ('partial repair variant: cumulative weight', [[1000, 4001], ['friend', 'a', ' there ', 'a']], [[1000, 2385, 'friend'], [2385, 2615, 'a'], [2615, 3770, 'there'], [3770, 4001, 'a']]), ('normal control', [[1000, 1007], ['friend']], [[1000, 1007, 'friend']]), ('normal control', [[0, 1000], ['Longer chunk of text']], [[0, 1000, 'Longer chunk of text']]), ('normal control', [[12345, 15346], ['xyz']], [[12345, 15346, 'xyz']])], [('regression: cumulative weight', [[100, 1100], [' x ', 'y']], [[100, 600, 'x'], [600, 1100, 'y']]), ('regression variant: cumulative weight', [[0, 3001], ['ok ', ' there ']], [[0, 857, 'ok'], [857, 3001, 'there']]), ('partial repair probe: cumulative weight', [[1000, 1999], ['ok ', 'Hello']], [[1000, 1285, 'ok'], [1285, 1999, 'Hello']]), ('partial repair variant: cumulative weight', [[0, 7], ['  ', 'ok ', '  ', 'ok ']], [[0, 1, ''], [1, 3, 'ok'], [3, 4, ''], [4, 7, 'ok']]), ('normal control', [[1000, 3500], ['a']], [[1000, 3500, 'a']]), ('normal control', [[12345, 12352], ['a']], [[12345, 12352, 'a']]), ('normal control', [[12345, 12352], ['Longer chunk of text']], [[12345, 12352, 'Longer chunk of text']])], [('regression: cumulative weight', [[0, 7], ['friend', 'Hello', 'ok ']], [[0, 3, 'friend'], [3, 5, 'Hello'], [5, 7, 'ok']]), ('regression variant: cumulative weight', [[1000, 1999], ['ok ', 'Hello']], [[1000, 1285, 'ok'], [1285, 1999, 'Hello']]), ('partial repair probe: cumulative weight', [[1000, 1999], ['ok ', '  ', 'friend', 'ok ']], [[1000, 1181, 'ok'], [1181, 1272, ''], [1272, 1817, 'friend'], [1817, 1999, 'ok']]), ('partial repair variant: cumulative weight', [[1000, 2000], ['ok ', '', '']], [[1000, 1500, 'ok'], [1500, 1750, ''], [1750, 2000, '']]), ('normal control', [[12345, 13345], ['Hello']], [[12345, 13345, 'Hello']]), ('normal control', [[12345, 15346], ['friend']], [[12345, 15346, 'friend']]), ('normal control', [[0, 100], ['Hello']], [[0, 100, 'Hello']])]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
regression: cumulative weight[[0, 500, 'ab'], [500, 1000, 'cd']][[0, 500, 'ab'], [500, 1000, 'cd']]Passed
regression variant: cumulative weight[[1000, 1000, 'a'], [1000, 1002, 'xyz'], [1002, 1006, 'friend'], [1006, 1007, 'a']][[1000, 1000, 'a'], [1000, 1002, 'xyz'], [1002, 1006, 'friend'], [1006, 1007, 'a']]Passed
partial repair probe: cumulative weight[[0, 60, 'friend'], [60, 90, 'ok'], [90, 120, 'ok']][[0, 60, 'friend'], [60, 80, 'ok'], [80, 100, 'ok']]Failed
partial repair variant: cumulative weight[[1000, 1025, 'there'], [1025, 1037, 'ok'], [1037, 1111, 'Longer chunk of text']][[1000, 1018, 'there'], [1018, 1025, 'ok'], [1025, 1100, 'Longer chunk of text']]Failed
normal control[[0, 2500, 'xyz']][[0, 2500, 'xyz']]Passed
normal control[[1000, 1999, 'friend']][[1000, 1999, 'friend']]Passed
normal control[[0, 3001, 'a']][[0, 3001, 'a']]Passed

SHA-256 / ab7649d1d10cf3806a45440fbf7a096aa3f4ae3c1746aabf805c3b3ea42ca2fd

3 / The verified repair

Exit 0
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(cue, parts):
    start,end=cue
    w=[max(1,len(p.strip())) for p in parts]
    total=sum(w)
    dur=end-start
    out=[]
    acc=0
    prev=start
    for p,x in zip(parts,w):
        acc+=x
        b=start+dur*acc//total
        out.append([prev,b,p.strip()])
        prev=b
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: cumulative weight', [[0, 1000], ['ab', 'cd']], [[0, 500, 'ab'], [500, 1000, 'cd']]), ('regression variant: cumulative weight', [[1000, 1007], ['a', 'xyz', 'friend', 'a']], [[1000, 1000, 'a'], [1000, 1002, 'xyz'], [1002, 1006, 'friend'], [1006, 1007, 'a']]), ('partial repair probe: cumulative weight', [[0, 100], ['friend', 'ok ', 'ok ']], [[0, 60, 'friend'], [60, 80, 'ok'], [80, 100, 'ok']]), ('partial repair variant: cumulative weight', [[1000, 1100], [' there ', 'ok ', 'Longer chunk of text']], [[1000, 1018, 'there'], [1018, 1025, 'ok'], [1025, 1100, 'Longer chunk of text']]), ('normal control', [[0, 2500], ['xyz']], [[0, 2500, 'xyz']]), ('normal control', [[1000, 1999], ['friend']], [[1000, 1999, 'friend']]), ('normal control', [[0, 3001], ['a']], [[0, 3001, 'a']])], [('regression: cumulative weight', [[0, 1000], ['a', '']], [[0, 500, 'a'], [500, 1000, '']]), ('regression variant: cumulative weight', [[1000, 1999], ['Longer chunk of text', 'xyz']], [[1000, 1868, 'Longer chunk of text'], [1868, 1999, 'xyz']]), ('partial repair probe: cumulative weight', [[0, 7], [' there ']], [[0, 7, 'there']]), ('partial repair variant: cumulative weight', [[1000, 1999], ['  ']], [[1000, 1999, '']]), ('normal control', [[12345, 15346], ['Hello']], [[12345, 15346, 'Hello']]), ('normal control', [[12345, 13345], ['xyz']], [[12345, 13345, 'xyz']]), ('normal control', [[12345, 13345], ['friend']], [[12345, 13345, 'friend']])], [('regression: cumulative weight', [[0, 7], ['abc', 'de', 'f']], [[0, 3, 'abc'], [3, 5, 'de'], [5, 7, 'f']]), ('regression variant: cumulative weight', [[0, 100], ['friend', 'ok ', 'ok ']], [[0, 60, 'friend'], [60, 80, 'ok'], [80, 100, 'ok']]), ('partial repair probe: cumulative weight', [[0, 3001], ['ok ', ' there ']], [[0, 857, 'ok'], [857, 3001, 'there']]), ('partial repair variant: cumulative weight', [[1000, 4001], ['friend', 'a', ' there ', 'a']], [[1000, 2385, 'friend'], [2385, 2615, 'a'], [2615, 3770, 'there'], [3770, 4001, 'a']]), ('normal control', [[1000, 1007], ['friend']], [[1000, 1007, 'friend']]), ('normal control', [[0, 1000], ['Longer chunk of text']], [[0, 1000, 'Longer chunk of text']]), ('normal control', [[12345, 15346], ['xyz']], [[12345, 15346, 'xyz']])], [('regression: cumulative weight', [[100, 1100], [' x ', 'y']], [[100, 600, 'x'], [600, 1100, 'y']]), ('regression variant: cumulative weight', [[0, 3001], ['ok ', ' there ']], [[0, 857, 'ok'], [857, 3001, 'there']]), ('partial repair probe: cumulative weight', [[1000, 1999], ['ok ', 'Hello']], [[1000, 1285, 'ok'], [1285, 1999, 'Hello']]), ('partial repair variant: cumulative weight', [[0, 7], ['  ', 'ok ', '  ', 'ok ']], [[0, 1, ''], [1, 3, 'ok'], [3, 4, ''], [4, 7, 'ok']]), ('normal control', [[1000, 3500], ['a']], [[1000, 3500, 'a']]), ('normal control', [[12345, 12352], ['a']], [[12345, 12352, 'a']]), ('normal control', [[12345, 12352], ['Longer chunk of text']], [[12345, 12352, 'Longer chunk of text']])], [('regression: cumulative weight', [[0, 7], ['friend', 'Hello', 'ok ']], [[0, 3, 'friend'], [3, 5, 'Hello'], [5, 7, 'ok']]), ('regression variant: cumulative weight', [[1000, 1999], ['ok ', 'Hello']], [[1000, 1285, 'ok'], [1285, 1999, 'Hello']]), ('partial repair probe: cumulative weight', [[1000, 1999], ['ok ', '  ', 'friend', 'ok ']], [[1000, 1181, 'ok'], [1181, 1272, ''], [1272, 1817, 'friend'], [1817, 1999, 'ok']]), ('partial repair variant: cumulative weight', [[1000, 2000], ['ok ', '', '']], [[1000, 1500, 'ok'], [1500, 1750, ''], [1750, 2000, '']]), ('normal control', [[12345, 13345], ['Hello']], [[12345, 13345, 'Hello']]), ('normal control', [[12345, 15346], ['friend']], [[12345, 15346, 'friend']]), ('normal control', [[0, 100], ['Hello']], [[0, 100, 'Hello']])]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(*args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
regression: cumulative weight[[0, 500, 'ab'], [500, 1000, 'cd']][[0, 500, 'ab'], [500, 1000, 'cd']]Passed
regression variant: cumulative weight[[1000, 1000, 'a'], [1000, 1002, 'xyz'], [1002, 1006, 'friend'], [1006, 1007, 'a']][[1000, 1000, 'a'], [1000, 1002, 'xyz'], [1002, 1006, 'friend'], [1006, 1007, 'a']]Passed
partial repair probe: cumulative weight[[0, 60, 'friend'], [60, 80, 'ok'], [80, 100, 'ok']][[0, 60, 'friend'], [60, 80, 'ok'], [80, 100, 'ok']]Passed
partial repair variant: cumulative weight[[1000, 1018, 'there'], [1018, 1025, 'ok'], [1025, 1100, 'Longer chunk of text']][[1000, 1018, 'there'], [1018, 1025, 'ok'], [1025, 1100, 'Longer chunk of text']]Passed
normal control[[0, 2500, 'xyz']][[0, 2500, 'xyz']]Passed
normal control[[1000, 1999, 'friend']][[1000, 1999, 'friend']]Passed
normal control[[0, 3001, 'a']][[0, 3001, 'a']]Passed

SHA-256 / 621d18f40e44e7d3345b72aacd373045b7c7490543d38a4c2a95798f39ed58ae

Verification & scope

A deterministic bounded teaching model with a stipulated toy contract; it does not claim conformance to any subtitle standard. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:49:32.100364+00:00.

Case digest / e0f04d6e0f190ae025c5ac310b50a999ae4ae582923583503969ef555942ceb9