FAILURE MAP
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FA-78391 / Broadcast timecode arithmetic / Open access

Drop-frame 29.97 label to frame count: drop separator set · case 01

Labels using the period or comma drop-frame spelling are rejected.

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

ROOT CAUSE

Only the semicolon is accepted as the drop-frame separator.

THE FAILURE

Only the semicolon is accepted as the drop-frame separator.

Unsuccessful approach: Accepting a colon instead admits non-drop labels while still refusing the period and comma forms.

Case contract

Parse HH:MM:SS;FF drop-frame 29.97 labels (the last separator may be ";", "," or "."). Labels ;00 and ;01 at second 00 of minutes not divisible by 10 do not exist and return None, as do out-of-range fields (hours 0-23, frames 0-29). Frame count = nominal 30 fps count minus 2 per elapsed minute except every tenth minute.

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
import re
N = 1
observations = []
def solve(tc):
    m=re.fullmatch(r'(\d{2}):(\d{2}):(\d{2});(\d{2})',tc)
    if not m:
        return None
    h,mi,s,f=map(int,m.groups())
    if h>23 or mi>59 or s>59:
        return None
    if f>29:
        return None
    if s==0 and f<2 and mi%10!=0:
        return None
    tm=h*60+mi
    return (tm*60+s)*30+f-2*(tm-tm//10)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: drop separator set', ['23:00:00.02'], 2481518), ('regression variant: drop separator set', ['23:20:00,00'], 2517480), ('partial repair probe: drop separator set', ['09:59:01.03'], 1077153), ('partial repair variant: drop separator set', ['01:01:00,02'], 109692), ('boundary control', ['00:01:00;02'], 1800), ('boundary control', ['01:00:00;00'], 107892), ('normal control', ['00:01:00;00'], None), ('normal control', ['00:00:59;29'], 1799), ('normal control', ['23:59:59;29'], 2589407)], [('regression: drop separator set', ['09:59:01.03'], 1077153), ('regression variant: drop separator set', ['01:01:00,02'], 109692), ('partial repair probe: drop separator set', ['23:10:01.01'], 2499529), ('partial repair variant: drop separator set', ['09:00:01,29'], 971087), ('boundary control', ['00:01:00;00'], None), ('boundary control', ['00:00:59;29'], 1799), ('normal control', ['24:00:00:31'], None), ('normal control', ['09:11:60.03'], None), ('normal control', ['24:20:59,31'], None)], [('regression: drop separator set', ['23:10:01.01'], 2499529), ('regression variant: drop separator set', ['09:00:01,29'], 971087), ('partial repair probe: drop separator set', ['00:11:00.03'], 19783), ('partial repair variant: drop separator set', ['23:09:00,15'], 2497713), ('boundary control', ['00:10:00;00'], 17982), ('boundary control', ['23:59:59;29'], 2589407), ('normal control', ['00:01:01;03'], 1831), ('normal control', ['01:60:00,02'], None), ('normal control', ['23:59:60,00'], None)], [('regression: drop separator set', ['00:11:00.03'], 19783), ('regression variant: drop separator set', ['23:09:00,15'], 2497713), ('partial repair probe: drop separator set', ['09:00:01.02'], 971060), ('partial repair variant: drop separator set', ['00:01:00.15'], 1813), ('boundary control', ['01:00:00;00'], 107892), ('boundary control', ['00:01:00;02'], 1800), ('normal control', ['23:11:59;00'], 2503066), ('normal control', ['01:20:60;00'], None), ('normal control', ['09:60:00:31'], None)], [('regression: drop separator set', ['09:00:01.02'], 971060), ('regression variant: drop separator set', ['00:01:00.15'], 1813), ('partial repair probe: drop separator set', ['23:00:01:29'], None), ('partial repair variant: drop separator set', ['09:10:00,02'], 989012), ('boundary control', ['00:00:59;29'], 1799), ('boundary control', ['00:01:00;00'], None), ('normal control', ['01:11:01;30'], None), ('normal control', ['24:60:01:02'], None), ('normal control', ['01:59:60;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: drop separator setNone2481518Failed
regression variant: drop separator setNone2517480Failed
partial repair probe: drop separator setNone1077153Failed
partial repair variant: drop separator setNone109692Failed
boundary control18001800Passed
boundary control107892107892Passed
normal controlNoneNonePassed
normal control17991799Passed
normal control25894072589407Passed

SHA-256 / 7349c0fa202b48353cb6b29460f93967af56235f81e4d26e4c7ec7428bc1b839

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json
import re
N = 1
observations = []
def solve(tc):
    m=re.fullmatch(r'(\d{2}):(\d{2}):(\d{2})[;:](\d{2})',tc)
    if not m:
        return None
    h,mi,s,f=map(int,m.groups())
    if h>23 or mi>59 or s>59:
        return None
    if f>29:
        return None
    if s==0 and f<2 and mi%10!=0:
        return None
    tm=h*60+mi
    return (tm*60+s)*30+f-2*(tm-tm//10)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: drop separator set', ['23:00:00.02'], 2481518), ('regression variant: drop separator set', ['23:20:00,00'], 2517480), ('partial repair probe: drop separator set', ['09:59:01.03'], 1077153), ('partial repair variant: drop separator set', ['01:01:00,02'], 109692), ('boundary control', ['00:01:00;02'], 1800), ('boundary control', ['01:00:00;00'], 107892), ('normal control', ['00:01:00;00'], None), ('normal control', ['00:00:59;29'], 1799), ('normal control', ['23:59:59;29'], 2589407)], [('regression: drop separator set', ['09:59:01.03'], 1077153), ('regression variant: drop separator set', ['01:01:00,02'], 109692), ('partial repair probe: drop separator set', ['23:10:01.01'], 2499529), ('partial repair variant: drop separator set', ['09:00:01,29'], 971087), ('boundary control', ['00:01:00;00'], None), ('boundary control', ['00:00:59;29'], 1799), ('normal control', ['24:00:00:31'], None), ('normal control', ['09:11:60.03'], None), ('normal control', ['24:20:59,31'], None)], [('regression: drop separator set', ['23:10:01.01'], 2499529), ('regression variant: drop separator set', ['09:00:01,29'], 971087), ('partial repair probe: drop separator set', ['00:11:00.03'], 19783), ('partial repair variant: drop separator set', ['23:09:00,15'], 2497713), ('boundary control', ['00:10:00;00'], 17982), ('boundary control', ['23:59:59;29'], 2589407), ('normal control', ['00:01:01;03'], 1831), ('normal control', ['01:60:00,02'], None), ('normal control', ['23:59:60,00'], None)], [('regression: drop separator set', ['00:11:00.03'], 19783), ('regression variant: drop separator set', ['23:09:00,15'], 2497713), ('partial repair probe: drop separator set', ['09:00:01.02'], 971060), ('partial repair variant: drop separator set', ['00:01:00.15'], 1813), ('boundary control', ['01:00:00;00'], 107892), ('boundary control', ['00:01:00;02'], 1800), ('normal control', ['23:11:59;00'], 2503066), ('normal control', ['01:20:60;00'], None), ('normal control', ['09:60:00:31'], None)], [('regression: drop separator set', ['09:00:01.02'], 971060), ('regression variant: drop separator set', ['00:01:00.15'], 1813), ('partial repair probe: drop separator set', ['23:00:01:29'], None), ('partial repair variant: drop separator set', ['09:10:00,02'], 989012), ('boundary control', ['00:00:59;29'], 1799), ('boundary control', ['00:01:00;00'], None), ('normal control', ['01:11:01;30'], None), ('normal control', ['24:60:01:02'], None), ('normal control', ['01:59:60;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: drop separator setNone2481518Failed
regression variant: drop separator setNone2517480Failed
partial repair probe: drop separator setNone1077153Failed
partial repair variant: drop separator setNone109692Failed
boundary control18001800Passed
boundary control107892107892Passed
normal controlNoneNonePassed
normal control17991799Passed
normal control25894072589407Passed

SHA-256 / 960c390e8a5ae4202ae21f93ae5b6048ec4e8360d666133c031620c1b5ce7444

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 9 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.

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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 2026-09-29T14:49:34.726784+00:00.

Case digest / 33ac84ec72a5d7f5eba9d6a8605992696c7b5fb44d16ab3d9733a92c0cf37c3e