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FA-78461 / Broadcast timecode arithmetic / Open access

Drop-frame label increment: minute carry · case 01

The label after 00:59:59;29 shows minute 60.

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

ROOT CAUSE

Minutes carry into the hour only above 60.

VERIFIED REPAIR

Carry into the hour when minutes reach 60.

Unsuccessful approach: Carrying at minute 59 skips the last minute of every hour.

Case contract

Given a valid drop-frame label at rate "29.97" (nominal 30, drop 2) or "59.94" (nominal 60, drop 4), return the next label: frames carry into seconds at the nominal rate, seconds into minutes, minutes into hours (wrapping at 24); on entering a new minute not divisible by 10 the first drop labels are skipped.

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, rate):
    n=30 if rate=='29.97' else 60
    drop=2 if n==30 else 4
    h,m,s,f=map(int,re.split('[:;]',tc))
    f+=1
    if f==n:
        f=0
        s+=1
        if s==60:
            s=0
            m+=1
            if m>60:
                m=0
                h=(h+1)%24
            if m%10!=0:
                f=drop
    return '%02d:%02d:%02d;%02d'%(h,m,s,f)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: minute carry', ['23:59:59;29', '29.97'], '00:00:00;00'), ('regression variant: minute carry', ['01:59:59;29', '29.97'], '02:00:00;00'), ('partial repair probe: minute carry', ['00:59:59;59', '59.94'], '01:00:00;00'), ('partial repair variant: minute carry', ['23:59:59;59', '59.94'], '00:00:00;00'), ('boundary control', ['00:00:59;29', '29.97'], '00:01:00;02'), ('boundary control', ['00:01:00;02', '29.97'], '00:01:00;03'), ('normal control', ['00:09:59;29', '29.97'], '00:10:00;00'), ('normal control', ['09:01:59;29', '29.97'], '09:02:00;02'), ('normal control', ['09:10:59;29', '29.97'], '09:11:00;02')], [('regression: minute carry', ['23:59:59;59', '59.94'], '00:00:00;00'), ('regression variant: minute carry', ['09:59:59;59', '59.94'], '10:00:00;00'), ('partial repair probe: minute carry', ['09:59:59;29', '29.97'], '10:00:00;00'), ('partial repair variant: minute carry', ['00:59:59;59', '59.94'], '01:00:00;00'), ('boundary control', ['00:09:59;29', '29.97'], '00:10:00;00'), ('boundary control', ['00:00:59;29', '29.97'], '00:01:00;02'), ('normal control', ['01:01:01;02', '29.97'], '01:01:01;03'), ('normal control', ['23:09:59;59', '59.94'], '23:10:00;00'), ('normal control', ['09:19:59;58', '59.94'], '09:19:59;59')], [('regression: minute carry', ['00:59:59;59', '59.94'], '01:00:00;00'), ('regression variant: minute carry', ['01:59:59;59', '59.94'], '02:00:00;00'), ('partial repair probe: minute carry', ['00:59:59;29', '29.97'], '01:00:00;00'), ('partial repair variant: minute carry', ['09:59:59;29', '29.97'], '10:00:00;00'), ('boundary control', ['00:00:59;59', '59.94'], '00:01:00;04'), ('boundary control', ['00:09:59;29', '29.97'], '00:10:00;00'), ('normal control', ['23:09:59;29', '29.97'], '23:10:00;00'), ('normal control', ['09:19:00;04', '59.94'], '09:19:00;05'), ('normal control', ['09:01:01;00', '29.97'], '09:01:01;01')], [('regression: minute carry', ['09:59:59;29', '29.97'], '10:00:00;00'), ('regression variant: minute carry', ['23:59:59;29', '29.97'], '00:00:00;00'), ('partial repair probe: minute carry', ['01:59:59;29', '29.97'], '02:00:00;00'), ('partial repair variant: minute carry', ['00:59:59;29', '29.97'], '01:00:00;00'), ('boundary control', ['00:01:00;02', '29.97'], '00:01:00;03'), ('boundary control', ['00:00:59;59', '59.94'], '00:01:00;04'), ('normal control', ['01:29:58;58', '59.94'], '01:29:58;59'), ('normal control', ['23:00:00;00', '59.94'], '23:00:00;01'), ('normal control', ['00:00:01;58', '59.94'], '00:00:01;59')], [('regression: minute carry', ['00:59:59;29', '29.97'], '01:00:00;00'), ('regression variant: minute carry', ['23:59:59;59', '59.94'], '00:00:00;00'), ('partial repair probe: minute carry', ['09:59:59;59', '59.94'], '10:00:00;00'), ('partial repair variant: minute carry', ['01:59:59;29', '29.97'], '02:00:00;00'), ('boundary control', ['00:00:59;29', '29.97'], '00:01:00;02'), ('boundary control', ['00:01:00;02', '29.97'], '00:01:00;03'), ('normal control', ['01:01:59;29', '29.97'], '01:02:00;02'), ('normal control', ['23:29:01;15', '29.97'], '23:29:01;16'), ('normal control', ['23:29:00;04', '59.94'], '23:29:00;05')]]
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: minute carry23:60:00;0000:00:00;00Failed
regression variant: minute carry01:60:00;0002:00:00;00Failed
partial repair probe: minute carry00:60:00;0001:00:00;00Failed
partial repair variant: minute carry23:60:00;0000:00:00;00Failed
boundary control00:01:00;0200:01:00;02Passed
boundary control00:01:00;0300:01:00;03Passed
normal control00:10:00;0000:10:00;00Passed
normal control09:02:00;0209:02:00;02Passed
normal control09:11:00;0209:11:00;02Passed

SHA-256 / 748c67847406ca90d93e6db2652a6322806d29caacb0be5e059b657c77972549

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json
import re
N = 1
observations = []
def solve(tc, rate):
    n=30 if rate=='29.97' else 60
    drop=2 if n==30 else 4
    h,m,s,f=map(int,re.split('[:;]',tc))
    f+=1
    if f==n:
        f=0
        s+=1
        if s==60:
            s=0
            m+=1
            if m==59:
                m=0
                h=(h+1)%24
            if m%10!=0:
                f=drop
    return '%02d:%02d:%02d;%02d'%(h,m,s,f)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: minute carry', ['23:59:59;29', '29.97'], '00:00:00;00'), ('regression variant: minute carry', ['01:59:59;29', '29.97'], '02:00:00;00'), ('partial repair probe: minute carry', ['00:59:59;59', '59.94'], '01:00:00;00'), ('partial repair variant: minute carry', ['23:59:59;59', '59.94'], '00:00:00;00'), ('boundary control', ['00:00:59;29', '29.97'], '00:01:00;02'), ('boundary control', ['00:01:00;02', '29.97'], '00:01:00;03'), ('normal control', ['00:09:59;29', '29.97'], '00:10:00;00'), ('normal control', ['09:01:59;29', '29.97'], '09:02:00;02'), ('normal control', ['09:10:59;29', '29.97'], '09:11:00;02')], [('regression: minute carry', ['23:59:59;59', '59.94'], '00:00:00;00'), ('regression variant: minute carry', ['09:59:59;59', '59.94'], '10:00:00;00'), ('partial repair probe: minute carry', ['09:59:59;29', '29.97'], '10:00:00;00'), ('partial repair variant: minute carry', ['00:59:59;59', '59.94'], '01:00:00;00'), ('boundary control', ['00:09:59;29', '29.97'], '00:10:00;00'), ('boundary control', ['00:00:59;29', '29.97'], '00:01:00;02'), ('normal control', ['01:01:01;02', '29.97'], '01:01:01;03'), ('normal control', ['23:09:59;59', '59.94'], '23:10:00;00'), ('normal control', ['09:19:59;58', '59.94'], '09:19:59;59')], [('regression: minute carry', ['00:59:59;59', '59.94'], '01:00:00;00'), ('regression variant: minute carry', ['01:59:59;59', '59.94'], '02:00:00;00'), ('partial repair probe: minute carry', ['00:59:59;29', '29.97'], '01:00:00;00'), ('partial repair variant: minute carry', ['09:59:59;29', '29.97'], '10:00:00;00'), ('boundary control', ['00:00:59;59', '59.94'], '00:01:00;04'), ('boundary control', ['00:09:59;29', '29.97'], '00:10:00;00'), ('normal control', ['23:09:59;29', '29.97'], '23:10:00;00'), ('normal control', ['09:19:00;04', '59.94'], '09:19:00;05'), ('normal control', ['09:01:01;00', '29.97'], '09:01:01;01')], [('regression: minute carry', ['09:59:59;29', '29.97'], '10:00:00;00'), ('regression variant: minute carry', ['23:59:59;29', '29.97'], '00:00:00;00'), ('partial repair probe: minute carry', ['01:59:59;29', '29.97'], '02:00:00;00'), ('partial repair variant: minute carry', ['00:59:59;29', '29.97'], '01:00:00;00'), ('boundary control', ['00:01:00;02', '29.97'], '00:01:00;03'), ('boundary control', ['00:00:59;59', '59.94'], '00:01:00;04'), ('normal control', ['01:29:58;58', '59.94'], '01:29:58;59'), ('normal control', ['23:00:00;00', '59.94'], '23:00:00;01'), ('normal control', ['00:00:01;58', '59.94'], '00:00:01;59')], [('regression: minute carry', ['00:59:59;29', '29.97'], '01:00:00;00'), ('regression variant: minute carry', ['23:59:59;59', '59.94'], '00:00:00;00'), ('partial repair probe: minute carry', ['09:59:59;59', '59.94'], '10:00:00;00'), ('partial repair variant: minute carry', ['01:59:59;29', '29.97'], '02:00:00;00'), ('boundary control', ['00:00:59;29', '29.97'], '00:01:00;02'), ('boundary control', ['00:01:00;02', '29.97'], '00:01:00;03'), ('normal control', ['01:01:59;29', '29.97'], '01:02:00;02'), ('normal control', ['23:29:01;15', '29.97'], '23:29:01;16'), ('normal control', ['23:29:00;04', '59.94'], '23:29:00;05')]]
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: minute carry23:60:00;0000:00:00;00Failed
regression variant: minute carry01:60:00;0002:00:00;00Failed
partial repair probe: minute carry00:60:00;0001:00:00;00Failed
partial repair variant: minute carry23:60:00;0000:00:00;00Failed
boundary control00:01:00;0200:01:00;02Passed
boundary control00:01:00;0300:01:00;03Passed
normal control00:10:00;0000:10:00;00Passed
normal control09:02:00;0209:02:00;02Passed
normal control09:11:00;0209:11:00;02Passed

SHA-256 / 2dbd9e6d543989927b9156b2a68c5f23140a3dbbc3599dd8f1caaea15ddf7aab

3 / The verified repair

Exit 0
"""Failure Map reference implementation. Python standard library only."""
import json
import re
N = 1
observations = []
def solve(tc, rate):
    n=30 if rate=='29.97' else 60
    drop=2 if n==30 else 4
    h,m,s,f=map(int,re.split('[:;]',tc))
    f+=1
    if f==n:
        f=0
        s+=1
        if s==60:
            s=0
            m+=1
            if m==60:
                m=0
                h=(h+1)%24
            if m%10!=0:
                f=drop
    return '%02d:%02d:%02d;%02d'%(h,m,s,f)
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('regression: minute carry', ['23:59:59;29', '29.97'], '00:00:00;00'), ('regression variant: minute carry', ['01:59:59;29', '29.97'], '02:00:00;00'), ('partial repair probe: minute carry', ['00:59:59;59', '59.94'], '01:00:00;00'), ('partial repair variant: minute carry', ['23:59:59;59', '59.94'], '00:00:00;00'), ('boundary control', ['00:00:59;29', '29.97'], '00:01:00;02'), ('boundary control', ['00:01:00;02', '29.97'], '00:01:00;03'), ('normal control', ['00:09:59;29', '29.97'], '00:10:00;00'), ('normal control', ['09:01:59;29', '29.97'], '09:02:00;02'), ('normal control', ['09:10:59;29', '29.97'], '09:11:00;02')], [('regression: minute carry', ['23:59:59;59', '59.94'], '00:00:00;00'), ('regression variant: minute carry', ['09:59:59;59', '59.94'], '10:00:00;00'), ('partial repair probe: minute carry', ['09:59:59;29', '29.97'], '10:00:00;00'), ('partial repair variant: minute carry', ['00:59:59;59', '59.94'], '01:00:00;00'), ('boundary control', ['00:09:59;29', '29.97'], '00:10:00;00'), ('boundary control', ['00:00:59;29', '29.97'], '00:01:00;02'), ('normal control', ['01:01:01;02', '29.97'], '01:01:01;03'), ('normal control', ['23:09:59;59', '59.94'], '23:10:00;00'), ('normal control', ['09:19:59;58', '59.94'], '09:19:59;59')], [('regression: minute carry', ['00:59:59;59', '59.94'], '01:00:00;00'), ('regression variant: minute carry', ['01:59:59;59', '59.94'], '02:00:00;00'), ('partial repair probe: minute carry', ['00:59:59;29', '29.97'], '01:00:00;00'), ('partial repair variant: minute carry', ['09:59:59;29', '29.97'], '10:00:00;00'), ('boundary control', ['00:00:59;59', '59.94'], '00:01:00;04'), ('boundary control', ['00:09:59;29', '29.97'], '00:10:00;00'), ('normal control', ['23:09:59;29', '29.97'], '23:10:00;00'), ('normal control', ['09:19:00;04', '59.94'], '09:19:00;05'), ('normal control', ['09:01:01;00', '29.97'], '09:01:01;01')], [('regression: minute carry', ['09:59:59;29', '29.97'], '10:00:00;00'), ('regression variant: minute carry', ['23:59:59;29', '29.97'], '00:00:00;00'), ('partial repair probe: minute carry', ['01:59:59;29', '29.97'], '02:00:00;00'), ('partial repair variant: minute carry', ['00:59:59;29', '29.97'], '01:00:00;00'), ('boundary control', ['00:01:00;02', '29.97'], '00:01:00;03'), ('boundary control', ['00:00:59;59', '59.94'], '00:01:00;04'), ('normal control', ['01:29:58;58', '59.94'], '01:29:58;59'), ('normal control', ['23:00:00;00', '59.94'], '23:00:00;01'), ('normal control', ['00:00:01;58', '59.94'], '00:00:01;59')], [('regression: minute carry', ['00:59:59;29', '29.97'], '01:00:00;00'), ('regression variant: minute carry', ['23:59:59;59', '59.94'], '00:00:00;00'), ('partial repair probe: minute carry', ['09:59:59;59', '59.94'], '10:00:00;00'), ('partial repair variant: minute carry', ['01:59:59;29', '29.97'], '02:00:00;00'), ('boundary control', ['00:00:59;29', '29.97'], '00:01:00;02'), ('boundary control', ['00:01:00;02', '29.97'], '00:01:00;03'), ('normal control', ['01:01:59;29', '29.97'], '01:02:00;02'), ('normal control', ['23:29:01;15', '29.97'], '23:29:01;16'), ('normal control', ['23:29:00;04', '59.94'], '23:29:00;05')]]
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: minute carry00:00:00;0000:00:00;00Passed
regression variant: minute carry02:00:00;0002:00:00;00Passed
partial repair probe: minute carry01:00:00;0001:00:00;00Passed
partial repair variant: minute carry00:00:00;0000:00:00;00Passed
boundary control00:01:00;0200:01:00;02Passed
boundary control00:01:00;0300:01:00;03Passed
normal control00:10:00;0000:10:00;00Passed
normal control09:02:00;0209:02:00;02Passed
normal control09:11:00;0209:11:00;02Passed

SHA-256 / d1a7cc0902de6a37bea788cc7ba67bddb6fe71823b54e5213fbac7d12c930636

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 2026-09-29T14:49:35.361181+00:00.

Case digest / 9acf42f8a365660f1db8a031b45b7d71d9b413689a9f22d2828c0c375f544c52