FAILURE MAP
← Case archive

FA-78361 / Broadcast timecode arithmetic / Open access

Non-drop timecode label parsing: separator policy · case 01

Drop-frame labels are silently parsed as non-drop counts, shifting events by up to 108 frames per hour.

Verified by executionVariant 1 · 9 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The parser normalizes the drop-frame semicolon to a colon.

VERIFIED REPAIR

Split on colons only so drop-frame labels are refused.

Unsuccessful approach: Normalizing the period separator still accepts a drop-frame spelling.

Case contract

Parse a non-drop label HH:MM:SS:FF (exactly two digits per field, colons only) at integer fps to a frame count from midnight. Hours 0-23, minutes and seconds 0-59, frames below fps; anything else, including drop-frame separators, returns None.

Why this case matters

Timecode arithmetic errors misplace edits, commercial breaks and captions against the broadcast clock.

1 / The failure

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

N = 1
observations = []
def solve(tc, fps):
    f=tc.replace(';',':').split(':')
    if len(f)!=4 or not all(len(x)==2 and x.isdigit() for x in f):
        return None
    h,m,s,fr=map(int,f)
    if h>23:
        return None
    if m>59 or s>59:
        return None
    if fr>=fps:
        return None
    return ((h*60+m)*60+s)*fps+fr
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: separator policy', ['01:00:00;00', 30], None), ('regression variant: separator policy', ['23:00:59;00', 30], None), ('partial repair probe: separator policy', ['23:59:59.00', 24], None), ('partial repair variant: separator policy', ['00:07:00.24', 25], None), ('boundary control', ['00:00:00:00', 25], 0), ('boundary control', ['00:00:00:25', 25], None), ('normal control', ['23:59:59:24', 25], 2159999), ('normal control', ['1:59:59:24', 30], None), ('normal control', ['23:07:60.30', 30], None)], [('regression: separator policy', ['01:59:59;25', 30], None), ('regression variant: separator policy', ['01:07:59;24', 25], None), ('partial repair probe: separator policy', ['01:00:00.24', 25], None), ('partial repair variant: separator policy', ['01:00:00.00', 24], None), ('boundary control', ['23:59:59:24', 25], 2159999), ('boundary control', ['00:00:00:00', 25], 0), ('normal control', ['24:07:59:30', 30], None), ('normal control', ['24:07:60:30', 30], None), ('normal control', ['00:07:60:30', 30], None)], [('regression: separator policy', ['00:00:59;00', 24], None), ('regression variant: separator policy', ['00:07:59;00', 25], None), ('partial repair probe: separator policy', ['00:00:59.24', 30], None), ('partial repair variant: separator policy', ['23:59:59.00', 24], None), ('boundary control', ['24:00:00:00', 25], None), ('boundary control', ['23:59:59:24', 25], 2159999), ('normal control', ['99:07:00:30', 25], None), ('normal control', ['00:59:59:24', 25], 89999), ('normal control', ['01:07:00:25', 24], None)], [('regression: separator policy', ['01:00:59;24', 25], None), ('regression variant: separator policy', ['00:07:59;29', 30], None), ('partial repair probe: separator policy', ['23:59:59.29', 30], None), ('partial repair variant: separator policy', ['01:00:00.24', 25], None), ('boundary control', ['00:00:00:25', 25], None), ('boundary control', ['24:00:00:00', 25], None), ('normal control', ['01:00:60:29', 24], None), ('normal control', ['23:59:5:29', 25], None), ('normal control', ['1:59:00;25', 25], None)], [('regression: separator policy', ['23:59:00;24', 25], None), ('regression variant: separator policy', ['01:00:00;00', 30], None), ('partial repair probe: separator policy', ['23:59:59.00', 30], None), ('partial repair variant: separator policy', ['00:00:59.24', 30], None), ('boundary control', ['00:00:00:00', 25], 0), ('boundary control', ['00:00:00:25', 25], None), ('normal control', ['99:60:59:25', 25], None), ('normal control', ['24:00:60:25', 30], None), ('normal control', ['24:60:5.00', 30], None)]]
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: separator policy108000NoneFailed
regression variant: separator policy2485770NoneFailed
partial repair probe: separator policyNoneNonePassed
partial repair variant: separator policyNoneNonePassed
boundary control00Passed
boundary controlNoneNonePassed
normal control21599992159999Passed
normal controlNoneNonePassed
normal controlNoneNonePassed

SHA-256 / 312bfd00a199a7685fc7fc2ed23e0e9ecb5523096372a9b65059471008e235e1

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(tc, fps):
    f=tc.replace('.',':').split(':')
    if len(f)!=4 or not all(len(x)==2 and x.isdigit() for x in f):
        return None
    h,m,s,fr=map(int,f)
    if h>23:
        return None
    if m>59 or s>59:
        return None
    if fr>=fps:
        return None
    return ((h*60+m)*60+s)*fps+fr
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: separator policy', ['01:00:00;00', 30], None), ('regression variant: separator policy', ['23:00:59;00', 30], None), ('partial repair probe: separator policy', ['23:59:59.00', 24], None), ('partial repair variant: separator policy', ['00:07:00.24', 25], None), ('boundary control', ['00:00:00:00', 25], 0), ('boundary control', ['00:00:00:25', 25], None), ('normal control', ['23:59:59:24', 25], 2159999), ('normal control', ['1:59:59:24', 30], None), ('normal control', ['23:07:60.30', 30], None)], [('regression: separator policy', ['01:59:59;25', 30], None), ('regression variant: separator policy', ['01:07:59;24', 25], None), ('partial repair probe: separator policy', ['01:00:00.24', 25], None), ('partial repair variant: separator policy', ['01:00:00.00', 24], None), ('boundary control', ['23:59:59:24', 25], 2159999), ('boundary control', ['00:00:00:00', 25], 0), ('normal control', ['24:07:59:30', 30], None), ('normal control', ['24:07:60:30', 30], None), ('normal control', ['00:07:60:30', 30], None)], [('regression: separator policy', ['00:00:59;00', 24], None), ('regression variant: separator policy', ['00:07:59;00', 25], None), ('partial repair probe: separator policy', ['00:00:59.24', 30], None), ('partial repair variant: separator policy', ['23:59:59.00', 24], None), ('boundary control', ['24:00:00:00', 25], None), ('boundary control', ['23:59:59:24', 25], 2159999), ('normal control', ['99:07:00:30', 25], None), ('normal control', ['00:59:59:24', 25], 89999), ('normal control', ['01:07:00:25', 24], None)], [('regression: separator policy', ['01:00:59;24', 25], None), ('regression variant: separator policy', ['00:07:59;29', 30], None), ('partial repair probe: separator policy', ['23:59:59.29', 30], None), ('partial repair variant: separator policy', ['01:00:00.24', 25], None), ('boundary control', ['00:00:00:25', 25], None), ('boundary control', ['24:00:00:00', 25], None), ('normal control', ['01:00:60:29', 24], None), ('normal control', ['23:59:5:29', 25], None), ('normal control', ['1:59:00;25', 25], None)], [('regression: separator policy', ['23:59:00;24', 25], None), ('regression variant: separator policy', ['01:00:00;00', 30], None), ('partial repair probe: separator policy', ['23:59:59.00', 30], None), ('partial repair variant: separator policy', ['00:00:59.24', 30], None), ('boundary control', ['00:00:00:00', 25], 0), ('boundary control', ['00:00:00:25', 25], None), ('normal control', ['99:60:59:25', 25], None), ('normal control', ['24:00:60:25', 30], None), ('normal control', ['24:60:5.00', 30], None)]]
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: separator policyNoneNonePassed
regression variant: separator policyNoneNonePassed
partial repair probe: separator policy2073576NoneFailed
partial repair variant: separator policy10524NoneFailed
boundary control00Passed
boundary controlNoneNonePassed
normal control21599992159999Passed
normal controlNoneNonePassed
normal controlNoneNonePassed

SHA-256 / a9713417f3f972d48b855363018dd67b9eae899c2150cc6c7de6c95fc00e2978

3 / The verified repair

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

N = 1
observations = []
def solve(tc, fps):
    f=tc.split(':')
    if len(f)!=4 or not all(len(x)==2 and x.isdigit() for x in f):
        return None
    h,m,s,fr=map(int,f)
    if h>23:
        return None
    if m>59 or s>59:
        return None
    if fr>=fps:
        return None
    return ((h*60+m)*60+s)*fps+fr
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: separator policy', ['01:00:00;00', 30], None), ('regression variant: separator policy', ['23:00:59;00', 30], None), ('partial repair probe: separator policy', ['23:59:59.00', 24], None), ('partial repair variant: separator policy', ['00:07:00.24', 25], None), ('boundary control', ['00:00:00:00', 25], 0), ('boundary control', ['00:00:00:25', 25], None), ('normal control', ['23:59:59:24', 25], 2159999), ('normal control', ['1:59:59:24', 30], None), ('normal control', ['23:07:60.30', 30], None)], [('regression: separator policy', ['01:59:59;25', 30], None), ('regression variant: separator policy', ['01:07:59;24', 25], None), ('partial repair probe: separator policy', ['01:00:00.24', 25], None), ('partial repair variant: separator policy', ['01:00:00.00', 24], None), ('boundary control', ['23:59:59:24', 25], 2159999), ('boundary control', ['00:00:00:00', 25], 0), ('normal control', ['24:07:59:30', 30], None), ('normal control', ['24:07:60:30', 30], None), ('normal control', ['00:07:60:30', 30], None)], [('regression: separator policy', ['00:00:59;00', 24], None), ('regression variant: separator policy', ['00:07:59;00', 25], None), ('partial repair probe: separator policy', ['00:00:59.24', 30], None), ('partial repair variant: separator policy', ['23:59:59.00', 24], None), ('boundary control', ['24:00:00:00', 25], None), ('boundary control', ['23:59:59:24', 25], 2159999), ('normal control', ['99:07:00:30', 25], None), ('normal control', ['00:59:59:24', 25], 89999), ('normal control', ['01:07:00:25', 24], None)], [('regression: separator policy', ['01:00:59;24', 25], None), ('regression variant: separator policy', ['00:07:59;29', 30], None), ('partial repair probe: separator policy', ['23:59:59.29', 30], None), ('partial repair variant: separator policy', ['01:00:00.24', 25], None), ('boundary control', ['00:00:00:25', 25], None), ('boundary control', ['24:00:00:00', 25], None), ('normal control', ['01:00:60:29', 24], None), ('normal control', ['23:59:5:29', 25], None), ('normal control', ['1:59:00;25', 25], None)], [('regression: separator policy', ['23:59:00;24', 25], None), ('regression variant: separator policy', ['01:00:00;00', 30], None), ('partial repair probe: separator policy', ['23:59:59.00', 30], None), ('partial repair variant: separator policy', ['00:00:59.24', 30], None), ('boundary control', ['00:00:00:00', 25], 0), ('boundary control', ['00:00:00:25', 25], None), ('normal control', ['99:60:59:25', 25], None), ('normal control', ['24:00:60:25', 30], None), ('normal control', ['24:60:5.00', 30], None)]]
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: separator policyNoneNonePassed
regression variant: separator policyNoneNonePassed
partial repair probe: separator policyNoneNonePassed
partial repair variant: separator policyNoneNonePassed
boundary control00Passed
boundary controlNoneNonePassed
normal control21599992159999Passed
normal controlNoneNonePassed
normal controlNoneNonePassed

SHA-256 / 4fee335be459ea31f6b98e4a58b796dfafab8a73b621d93b853359f48dee61ed

Verification & scope

A deterministic bounded teaching model with a stipulated toy contract; it does not claim conformance to SMPTE or any broadcast 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 2026-09-29T14:49:34.680996+00:00.

Case digest / 71880f7a692f0bd9bd18b6ac91e617b2f140078b0b8feeb0fee83ee06de49f5f