FA-78001 / Subtitle cue timing / Open access

Minimum cue duration extension: never shorten · case 01

Short cues crowded by a close neighbour get even shorter or inverted.

Verified by executionVariant 1 · 8 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The neighbour-limited target is assigned even when it lies before the current end.

THE FAILURE

The neighbour-limited target is assigned even when it lies before the current end.

Unsuccessful approach: Taking the minimum never extends anything and can shorten crowded cues.

Case contract

Cues [start,end] may be unsorted; the neighbour of a cue is the next cue in (start, input index) order. A cue shorter than min_dur has its end extended to start+min_dur, limited to neighbour_start - min_gap; an end is never shortened. Output keeps input order.

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(cues, min_dur, min_gap):
    out=[list(c) for c in cues]
    order=sorted(range(len(out)),key=lambda k:(out[k][0],k))
    for pos,i in enumerate(order):
        c=out[i]
        if c[1]-c[0]>=min_dur:
            continue
        target=c[0]+min_dur
        if pos+1<len(order):
            target=min(target,out[order[pos+1]][0]-min_gap)
        c[1]=target
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: never shorten', [[[1000, 1960], [2000, 2300], [3000, 3999], [3000, 3001]], 1000, 40], [[1000, 1960], [2000, 2960], [3000, 3999], [3000, 4000]]), ('regression variant: never shorten', [[[0, 2000], [200, 1160], [500, 1499], [1186, 1187], [2429, 3430]], 1000, 40], [[0, 2000], [200, 1160], [500, 1499], [1186, 2186], [2429, 3430]]), ('partial repair probe: never shorten', [[[500, 600], [0, 100]], 700, 40], [[500, 1200], [0, 460]]), ('partial repair variant: never shorten', [[[500, 800], [500, 2500], [800, 1799], [1000, 1001], [1000, 3000]], 1000, 40], [[500, 800], [500, 2500], [800, 1799], [1000, 1001], [1000, 3000]]), ('boundary control', [[[0, 1000]], 1000, 0], [[0, 1000]]), ('normal control', [[[1000, 3000]], 1200, 0], [[1000, 3000]]), ('normal control', [[[200, 1201], [2000, 3001], [1000, 2000], [800, 1800]], 1000, 0], [[200, 1201], [2000, 3001], [1000, 2000], [800, 1800]]), ('normal control', [[[1500, 3500]], 700, 0], [[1500, 3500]])], [('regression: never shorten', [[[200, 500], [500, 800], [1500, 3500], [1500, 2699], [2000, 2001]], 1200, 40], [[200, 500], [500, 1460], [1500, 3500], [1500, 2699], [2000, 3200]]), ('regression variant: never shorten', [[[2000, 4000], [1500, 1600], [1500, 2699]], 1200, 80], [[2000, 4000], [1500, 1600], [1500, 2699]]), ('partial repair probe: never shorten', [[[1000, 2120], [200, 1400]], 1200, 80], [[1000, 2200], [200, 1400]]), ('partial repair variant: never shorten', [[[479, 2479], [2000, 2300], [1000, 2120], [800, 2001]], 1200, 80], [[479, 2479], [2000, 3200], [1000, 2120], [800, 2001]]), ('boundary control', [[[0, 1000]], 1000, 0], [[0, 1000]]), ('normal control', [[[1000, 3000], [3000, 4200]], 1200, 80], [[1000, 3000], [3000, 4200]]), ('normal control', [[[800, 1800], [800, 1800]], 1000, 80], [[800, 1800], [800, 1800]]), ('normal control', [[[200, 2200], [500, 1500], [1000, 3000], [1500, 2500], [1500, 2501]], 1000, 0], [[200, 2200], [500, 1500], [1000, 3000], [1500, 2500], [1500, 2501]])], [('regression: never shorten', [[[500, 800], [500, 2500], [800, 1799], [1000, 1001], [1000, 3000]], 1000, 40], [[500, 800], [500, 2500], [800, 1799], [1000, 1001], [1000, 3000]]), ('regression variant: never shorten', [[[800, 1760], [800, 1800], [1000, 1100], [1000, 1999]], 1000, 40], [[800, 1760], [800, 1800], [1000, 1100], [1000, 2000]]), ('partial repair probe: never shorten', [[[0, 1], [200, 900], [2000, 4000]], 700, 0], [[0, 200], [200, 900], [2000, 4000]]), ('partial repair variant: never shorten', [[[0, 2000], [200, 500]], 700, 80], [[0, 2000], [200, 900]]), ('boundary control', [[[0, 1000]], 1000, 0], [[0, 1000]]), ('normal control', [[[1000, 1701]], 700, 40], [[1000, 1701]]), ('normal control', [[[200, 1201], [0, 1001]], 1000, 0], [[200, 1201], [0, 1001]]), ('normal control', [[[4377, 5078]], 700, 40], [[4377, 5078]])], [('regression: never shorten', [[[479, 2479], [2000, 2300], [1000, 2120], [800, 2001]], 1200, 80], [[479, 2479], [2000, 3200], [1000, 2120], [800, 2001]]), ('regression variant: never shorten', [[[500, 2500], [500, 1120], [1000, 1699], [2000, 2701], [2766, 3465]], 700, 80], [[500, 2500], [500, 1120], [1000, 1700], [2000, 2701], [2766, 3466]]), ('partial repair probe: never shorten', [[[2000, 2001], [800, 1100]], 1000, 80], [[2000, 3000], [800, 1800]]), ('partial repair variant: never shorten', [[[3000, 3700], [500, 501]], 700, 0], [[3000, 3700], [500, 1200]]), ('boundary control', [[[0, 1000]], 1000, 0], [[0, 1000]]), ('normal control', [[[3000, 4200]], 1200, 0], [[3000, 4200]]), ('normal control', [[[800, 2800]], 1200, 0], [[800, 2800]]), ('normal control', [[[200, 1400]], 1200, 80], [[200, 1400]])], [('regression: never shorten', [[[200, 500], [496, 1497], [800, 1799], [3000, 3999]], 1000, 40], [[200, 500], [496, 1497], [800, 1800], [3000, 4000]]), ('regression variant: never shorten', [[[500, 501], [200, 1160], [0, 1], [500, 1460]], 1000, 40], [[500, 501], [200, 1160], [0, 160], [500, 1500]]), ('partial repair probe: never shorten', [[[1000, 1960], [2000, 2300], [3000, 3999], [3000, 3001]], 1000, 40], [[1000, 1960], [2000, 2960], [3000, 3999], [3000, 4000]]), ('partial repair variant: never shorten', [[[2000, 2999], [500, 1501]], 1000, 80], [[2000, 3000], [500, 1501]]), ('boundary control', [[[0, 1000]], 1000, 0], [[0, 1000]]), ('normal control', [[[200, 1400], [500, 1700]], 1200, 0], [[200, 1400], [500, 1700]]), ('normal control', [[[500, 1700]], 1200, 0], [[500, 1700]]), ('normal control', [[[1500, 2500]], 1000, 0], [[1500, 2500]])]]
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 fixture	Actual	Expected	Outcome
regression: never shorten	`[[1000, 1960], [2000, 2960], [3000, 2960], [3000, 4000]]`	`[[1000, 1960], [2000, 2960], [3000, 3999], [3000, 4000]]`	Failed
regression variant: never shorten	`[[0, 2000], [200, 460], [500, 1146], [1186, 2186], [2429, 3430]]`	`[[0, 2000], [200, 1160], [500, 1499], [1186, 2186], [2429, 3430]]`	Failed
partial repair probe: never shorten	`[[500, 1200], [0, 460]]`	`[[500, 1200], [0, 460]]`	Passed
partial repair variant: never shorten	`[[500, 460], [500, 2500], [800, 960], [1000, 960], [1000, 3000]]`	`[[500, 800], [500, 2500], [800, 1799], [1000, 1001], [1000, 3000]]`	Failed
boundary control	`[[0, 1000]]`	`[[0, 1000]]`	Passed
normal control	`[[1000, 3000]]`	`[[1000, 3000]]`	Passed
normal control	`[[200, 1201], [2000, 3001], [1000, 2000], [800, 1800]]`	`[[200, 1201], [2000, 3001], [1000, 2000], [800, 1800]]`	Passed
normal control	`[[1500, 3500]]`	`[[1500, 3500]]`	Passed

SHA-256 / d9682b3963281265488280b1174df6daa0181e3eb076e35ceb1fa458aa316980

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(cues, min_dur, min_gap):
    out=[list(c) for c in cues]
    order=sorted(range(len(out)),key=lambda k:(out[k][0],k))
    for pos,i in enumerate(order):
        c=out[i]
        if c[1]-c[0]>=min_dur:
            continue
        target=c[0]+min_dur
        if pos+1<len(order):
            target=min(target,out[order[pos+1]][0]-min_gap)
        c[1]=min(c[1],target)
    return out
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: never shorten', [[[1000, 1960], [2000, 2300], [3000, 3999], [3000, 3001]], 1000, 40], [[1000, 1960], [2000, 2960], [3000, 3999], [3000, 4000]]), ('regression variant: never shorten', [[[0, 2000], [200, 1160], [500, 1499], [1186, 1187], [2429, 3430]], 1000, 40], [[0, 2000], [200, 1160], [500, 1499], [1186, 2186], [2429, 3430]]), ('partial repair probe: never shorten', [[[500, 600], [0, 100]], 700, 40], [[500, 1200], [0, 460]]), ('partial repair variant: never shorten', [[[500, 800], [500, 2500], [800, 1799], [1000, 1001], [1000, 3000]], 1000, 40], [[500, 800], [500, 2500], [800, 1799], [1000, 1001], [1000, 3000]]), ('boundary control', [[[0, 1000]], 1000, 0], [[0, 1000]]), ('normal control', [[[1000, 3000]], 1200, 0], [[1000, 3000]]), ('normal control', [[[200, 1201], [2000, 3001], [1000, 2000], [800, 1800]], 1000, 0], [[200, 1201], [2000, 3001], [1000, 2000], [800, 1800]]), ('normal control', [[[1500, 3500]], 700, 0], [[1500, 3500]])], [('regression: never shorten', [[[200, 500], [500, 800], [1500, 3500], [1500, 2699], [2000, 2001]], 1200, 40], [[200, 500], [500, 1460], [1500, 3500], [1500, 2699], [2000, 3200]]), ('regression variant: never shorten', [[[2000, 4000], [1500, 1600], [1500, 2699]], 1200, 80], [[2000, 4000], [1500, 1600], [1500, 2699]]), ('partial repair probe: never shorten', [[[1000, 2120], [200, 1400]], 1200, 80], [[1000, 2200], [200, 1400]]), ('partial repair variant: never shorten', [[[479, 2479], [2000, 2300], [1000, 2120], [800, 2001]], 1200, 80], [[479, 2479], [2000, 3200], [1000, 2120], [800, 2001]]), ('boundary control', [[[0, 1000]], 1000, 0], [[0, 1000]]), ('normal control', [[[1000, 3000], [3000, 4200]], 1200, 80], [[1000, 3000], [3000, 4200]]), ('normal control', [[[800, 1800], [800, 1800]], 1000, 80], [[800, 1800], [800, 1800]]), ('normal control', [[[200, 2200], [500, 1500], [1000, 3000], [1500, 2500], [1500, 2501]], 1000, 0], [[200, 2200], [500, 1500], [1000, 3000], [1500, 2500], [1500, 2501]])], [('regression: never shorten', [[[500, 800], [500, 2500], [800, 1799], [1000, 1001], [1000, 3000]], 1000, 40], [[500, 800], [500, 2500], [800, 1799], [1000, 1001], [1000, 3000]]), ('regression variant: never shorten', [[[800, 1760], [800, 1800], [1000, 1100], [1000, 1999]], 1000, 40], [[800, 1760], [800, 1800], [1000, 1100], [1000, 2000]]), ('partial repair probe: never shorten', [[[0, 1], [200, 900], [2000, 4000]], 700, 0], [[0, 200], [200, 900], [2000, 4000]]), ('partial repair variant: never shorten', [[[0, 2000], [200, 500]], 700, 80], [[0, 2000], [200, 900]]), ('boundary control', [[[0, 1000]], 1000, 0], [[0, 1000]]), ('normal control', [[[1000, 1701]], 700, 40], [[1000, 1701]]), ('normal control', [[[200, 1201], [0, 1001]], 1000, 0], [[200, 1201], [0, 1001]]), ('normal control', [[[4377, 5078]], 700, 40], [[4377, 5078]])], [('regression: never shorten', [[[479, 2479], [2000, 2300], [1000, 2120], [800, 2001]], 1200, 80], [[479, 2479], [2000, 3200], [1000, 2120], [800, 2001]]), ('regression variant: never shorten', [[[500, 2500], [500, 1120], [1000, 1699], [2000, 2701], [2766, 3465]], 700, 80], [[500, 2500], [500, 1120], [1000, 1700], [2000, 2701], [2766, 3466]]), ('partial repair probe: never shorten', [[[2000, 2001], [800, 1100]], 1000, 80], [[2000, 3000], [800, 1800]]), ('partial repair variant: never shorten', [[[3000, 3700], [500, 501]], 700, 0], [[3000, 3700], [500, 1200]]), ('boundary control', [[[0, 1000]], 1000, 0], [[0, 1000]]), ('normal control', [[[3000, 4200]], 1200, 0], [[3000, 4200]]), ('normal control', [[[800, 2800]], 1200, 0], [[800, 2800]]), ('normal control', [[[200, 1400]], 1200, 80], [[200, 1400]])], [('regression: never shorten', [[[200, 500], [496, 1497], [800, 1799], [3000, 3999]], 1000, 40], [[200, 500], [496, 1497], [800, 1800], [3000, 4000]]), ('regression variant: never shorten', [[[500, 501], [200, 1160], [0, 1], [500, 1460]], 1000, 40], [[500, 501], [200, 1160], [0, 160], [500, 1500]]), ('partial repair probe: never shorten', [[[1000, 1960], [2000, 2300], [3000, 3999], [3000, 3001]], 1000, 40], [[1000, 1960], [2000, 2960], [3000, 3999], [3000, 4000]]), ('partial repair variant: never shorten', [[[2000, 2999], [500, 1501]], 1000, 80], [[2000, 3000], [500, 1501]]), ('boundary control', [[[0, 1000]], 1000, 0], [[0, 1000]]), ('normal control', [[[200, 1400], [500, 1700]], 1200, 0], [[200, 1400], [500, 1700]]), ('normal control', [[[500, 1700]], 1200, 0], [[500, 1700]]), ('normal control', [[[1500, 2500]], 1000, 0], [[1500, 2500]])]]
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 fixture	Actual	Expected	Outcome
regression: never shorten	`[[1000, 1960], [2000, 2300], [3000, 2960], [3000, 3001]]`	`[[1000, 1960], [2000, 2960], [3000, 3999], [3000, 4000]]`	Failed
regression variant: never shorten	`[[0, 2000], [200, 460], [500, 1146], [1186, 1187], [2429, 3430]]`	`[[0, 2000], [200, 1160], [500, 1499], [1186, 2186], [2429, 3430]]`	Failed
partial repair probe: never shorten	`[[500, 600], [0, 100]]`	`[[500, 1200], [0, 460]]`	Failed
partial repair variant: never shorten	`[[500, 460], [500, 2500], [800, 960], [1000, 960], [1000, 3000]]`	`[[500, 800], [500, 2500], [800, 1799], [1000, 1001], [1000, 3000]]`	Failed
boundary control	`[[0, 1000]]`	`[[0, 1000]]`	Passed
normal control	`[[1000, 3000]]`	`[[1000, 3000]]`	Passed
normal control	`[[200, 1201], [2000, 3001], [1000, 2000], [800, 1800]]`	`[[200, 1201], [2000, 3001], [1000, 2000], [800, 1800]]`	Passed
normal control	`[[1500, 3500]]`	`[[1500, 3500]]`	Passed

SHA-256 / 02cb3365df00a736d7e7f5322b120096e395bce926f30986c55ba3075de2e83c

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 8 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

Member access is invitation-based. Sign in with your invited account to inspect the repair.

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 2026-09-29T14:49:31.297096+00:00.

Case digest / 786894d4552c6e9d9bb9656ebcdf968f291208f16c566d8aadee4ebddf568c10