{"abstract":"With a non-zero cadence phase the first film frame does not start at field 0.","category":"Broadcast timecode arithmetic","checks":9,"contract":"Film frames follow the A2 B3 C2 D3 field cadence (10 fields per 4 film frames). phase is the cadence position (0=A..3=D) of film frame 0, which starts at video field 0. Negative n returns None. For film frame n return [video frame of its first field, \"upper\" for an even field index else \"lower\", number of fields].","evaluation_group":"w2-broadcast-timecode-arithmetic-pulldown-film-to-video","failed_approach":"Subtracting the phase index instead of its field offset misaligns the cadence.","family":"w2-broadcast-timecode-arithmetic-pulldown-film-to-video-phase-alignment","id":"FA-78551","implementations":{"attempt":{"sha256":"3863f3eb5d864157ed8ef4c1f636040bae789212d1f634bf8b9400bb8752f811","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(n, phase):\n    if n<0:\n        return None\n    def sf(a):\n        return 10*(a//4)+[0,2,5,7][a%4]\n    a=n+phase\n    start=sf(a)-phase\n    count=[2,3,2,3][a%4]\n    return [start//2,'upper' if start%2==0 else 'lower',count]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('regression: phase alignment', [0, 1], [0, 'upper', 3]), ('regression variant: phase alignment', [9, 3], [11, 'lower', 2]), ('partial repair probe: phase alignment', [9, 1], [11, 'lower', 2]), ('partial repair variant: phase alignment', [36, 1], [45, 'upper', 3]), ('boundary control', [0, 0], [0, 'upper', 2]), ('boundary control', [4, 0], [5, 'upper', 2]), ('normal control', [1, 0], [1, 'upper', 3]), ('normal control', [8, 0], [10, 'upper', 2]), ('normal control', [-3, 2], None)], [('regression: phase alignment', [2, 3], [2, 'lower', 3]), ('regression variant: phase alignment', [10, 1], [12, 'lower', 3]), ('partial repair probe: phase alignment', [35, 1], [44, 'upper', 2]), ('partial repair variant: phase alignment', [38, 3], [47, 'lower', 3]), ('boundary control', [1, 0], [1, 'upper', 3]), ('boundary control', [0, 0], [0, 'upper', 2]), ('normal control', [-6, 0], None), ('normal control', [-3, 1], None), ('normal control', [-6, 1], None)], [('regression: phase alignment', [9, 1], [11, 'lower', 2]), ('regression variant: phase alignment', [22, 2], [27, 'lower', 2]), ('partial repair probe: phase alignment', [34, 2], [42, 'lower', 2]), ('partial repair variant: phase alignment', [1, 3], [1, 'lower', 2]), ('boundary control', [3, 0], [3, 'lower', 3]), ('boundary control', [1, 0], [1, 'upper', 3]), ('normal control', [-3, 0], None), ('normal control', [-1, 1], None), ('normal control', [-5, 2], None)], [('regression: phase alignment', [35, 1], [44, 'upper', 2]), ('regression variant: phase alignment', [26, 2], [32, 'lower', 2]), ('partial repair probe: phase alignment', [9, 3], [11, 'lower', 2]), ('partial repair variant: phase alignment', [3, 2], [3, 'lower', 3]), ('boundary control', [4, 0], [5, 'upper', 2]), ('boundary control', [3, 0], [3, 'lower', 3]), ('normal control', [33, 0], [41, 'upper', 3]), ('normal control', [24, 0], [30, 'upper', 2]), ('normal control', [-4, 1], None)], [('regression: phase alignment', [34, 2], [42, 'lower', 2]), ('regression variant: phase alignment', [36, 1], [45, 'upper', 3]), ('partial repair probe: phase alignment', [10, 1], [12, 'lower', 3]), ('partial repair variant: phase alignment', [39, 2], [48, 'lower', 3]), ('boundary control', [0, 0], [0, 'upper', 2]), ('boundary control', [4, 0], [5, 'upper', 2]), ('normal control', [31, 0], [38, 'lower', 3]), ('normal control', [37, 0], [46, 'upper', 3]), ('normal control', [11, 0], [13, 'lower', 3])]]\nfor label, args, expected in fixtures[N-1]:\n    check(label, solve(*args), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"broken":{"sha256":"3c60d2824fe073522a0cb9c889786a0bcf72f4ee2b9de72b13b10d766669106f","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(n, phase):\n    if n<0:\n        return None\n    def sf(a):\n        return 10*(a//4)+[0,2,5,7][a%4]\n    a=n+phase\n    start=sf(a)\n    count=[2,3,2,3][a%4]\n    return [start//2,'upper' if start%2==0 else 'lower',count]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('regression: phase alignment', [0, 1], [0, 'upper', 3]), ('regression variant: phase alignment', [9, 3], [11, 'lower', 2]), ('partial repair probe: phase alignment', [9, 1], [11, 'lower', 2]), ('partial repair variant: phase alignment', [36, 1], [45, 'upper', 3]), ('boundary control', [0, 0], [0, 'upper', 2]), ('boundary control', [4, 0], [5, 'upper', 2]), ('normal control', [1, 0], [1, 'upper', 3]), ('normal control', [8, 0], [10, 'upper', 2]), ('normal control', [-3, 2], None)], [('regression: phase alignment', [2, 3], [2, 'lower', 3]), ('regression variant: phase alignment', [10, 1], [12, 'lower', 3]), ('partial repair probe: phase alignment', [35, 1], [44, 'upper', 2]), ('partial repair variant: phase alignment', [38, 3], [47, 'lower', 3]), ('boundary control', [1, 0], [1, 'upper', 3]), ('boundary control', [0, 0], [0, 'upper', 2]), ('normal control', [-6, 0], None), ('normal control', [-3, 1], None), ('normal control', [-6, 1], None)], [('regression: phase alignment', [9, 1], [11, 'lower', 2]), ('regression variant: phase alignment', [22, 2], [27, 'lower', 2]), ('partial repair probe: phase alignment', [34, 2], [42, 'lower', 2]), ('partial repair variant: phase alignment', [1, 3], [1, 'lower', 2]), ('boundary control', [3, 0], [3, 'lower', 3]), ('boundary control', [1, 0], [1, 'upper', 3]), ('normal control', [-3, 0], None), ('normal control', [-1, 1], None), ('normal control', [-5, 2], None)], [('regression: phase alignment', [35, 1], [44, 'upper', 2]), ('regression variant: phase alignment', [26, 2], [32, 'lower', 2]), ('partial repair probe: phase alignment', [9, 3], [11, 'lower', 2]), ('partial repair variant: phase alignment', [3, 2], [3, 'lower', 3]), ('boundary control', [4, 0], [5, 'upper', 2]), ('boundary control', [3, 0], [3, 'lower', 3]), ('normal control', [33, 0], [41, 'upper', 3]), ('normal control', [24, 0], [30, 'upper', 2]), ('normal control', [-4, 1], None)], [('regression: phase alignment', [34, 2], [42, 'lower', 2]), ('regression variant: phase alignment', [36, 1], [45, 'upper', 3]), ('partial repair probe: phase alignment', [10, 1], [12, 'lower', 3]), ('partial repair variant: phase alignment', [39, 2], [48, 'lower', 3]), ('boundary control', [0, 0], [0, 'upper', 2]), ('boundary control', [4, 0], [5, 'upper', 2]), ('normal control', [31, 0], [38, 'lower', 3]), ('normal control', [37, 0], [46, 'upper', 3]), ('normal control', [11, 0], [13, 'lower', 3])]]\nfor label, args, expected in fixtures[N-1]:\n    check(label, solve(*args), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"fixed":{"sha256":"78a5911724e6160396aa1a796f331908e70bb5b80eaf16d87aaf61cfc0928df3","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(n, phase):\n    if n<0:\n        return None\n    def sf(a):\n        return 10*(a//4)+[0,2,5,7][a%4]\n    a=n+phase\n    start=sf(a)-sf(phase)\n    count=[2,3,2,3][a%4]\n    return [start//2,'upper' if start%2==0 else 'lower',count]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('regression: phase alignment', [0, 1], [0, 'upper', 3]), ('regression variant: phase alignment', [9, 3], [11, 'lower', 2]), ('partial repair probe: phase alignment', [9, 1], [11, 'lower', 2]), ('partial repair variant: phase alignment', [36, 1], [45, 'upper', 3]), ('boundary control', [0, 0], [0, 'upper', 2]), ('boundary control', [4, 0], [5, 'upper', 2]), ('normal control', [1, 0], [1, 'upper', 3]), ('normal control', [8, 0], [10, 'upper', 2]), ('normal control', [-3, 2], None)], [('regression: phase alignment', [2, 3], [2, 'lower', 3]), ('regression variant: phase alignment', [10, 1], [12, 'lower', 3]), ('partial repair probe: phase alignment', [35, 1], [44, 'upper', 2]), ('partial repair variant: phase alignment', [38, 3], [47, 'lower', 3]), ('boundary control', [1, 0], [1, 'upper', 3]), ('boundary control', [0, 0], [0, 'upper', 2]), ('normal control', [-6, 0], None), ('normal control', [-3, 1], None), ('normal control', [-6, 1], None)], [('regression: phase alignment', [9, 1], [11, 'lower', 2]), ('regression variant: phase alignment', [22, 2], [27, 'lower', 2]), ('partial repair probe: phase alignment', [34, 2], [42, 'lower', 2]), ('partial repair variant: phase alignment', [1, 3], [1, 'lower', 2]), ('boundary control', [3, 0], [3, 'lower', 3]), ('boundary control', [1, 0], [1, 'upper', 3]), ('normal control', [-3, 0], None), ('normal control', [-1, 1], None), ('normal control', [-5, 2], None)], [('regression: phase alignment', [35, 1], [44, 'upper', 2]), ('regression variant: phase alignment', [26, 2], [32, 'lower', 2]), ('partial repair probe: phase alignment', [9, 3], [11, 'lower', 2]), ('partial repair variant: phase alignment', [3, 2], [3, 'lower', 3]), ('boundary control', [4, 0], [5, 'upper', 2]), ('boundary control', [3, 0], [3, 'lower', 3]), ('normal control', [33, 0], [41, 'upper', 3]), ('normal control', [24, 0], [30, 'upper', 2]), ('normal control', [-4, 1], None)], [('regression: phase alignment', [34, 2], [42, 'lower', 2]), ('regression variant: phase alignment', [36, 1], [45, 'upper', 3]), ('partial repair probe: phase alignment', [10, 1], [12, 'lower', 3]), ('partial repair variant: phase alignment', [39, 2], [48, 'lower', 3]), ('boundary control', [0, 0], [0, 'upper', 2]), ('boundary control', [4, 0], [5, 'upper', 2]), ('normal control', [31, 0], [38, 'lower', 3]), ('normal control', [37, 0], [46, 'upper', 3]), ('normal control', [11, 0], [13, 'lower', 3])]]\nfor label, args, expected in fixtures[N-1]:\n    check(label, solve(*args), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"}},"limitations":"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.","method":"Deterministic executable model with adversarial boundary fixtures.","provenance":{"created_by":"Failure Map","dependencies":"Python standard library","family":"w2-broadcast-timecode-arithmetic-pulldown-film-to-video-phase-alignment","generated_at":"2026-09-29T14:49:36.377368+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Timecode arithmetic errors misplace edits, commercial breaks and captions against the broadcast clock.","repair":"Subtract the field offset of the phase.","root_cause":"The field position of the starting cadence phase is not subtracted.","sha256":"d38038bfad556cff318fdb01572b3118615d40656ba6da52cbbc75ed372e0a54","title":"2:3 pulldown film frame placement: phase alignment · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":41.598,"exit_code":1,"observations":[{"actual":[0,"lower",3],"check":"regression: phase alignment","expected":[0,"upper",3],"passed":false},{"actual":[13,"lower",2],"check":"regression variant: phase alignment","expected":[11,"lower",2],"passed":false},{"actual":[12,"upper",2],"check":"partial repair probe: phase alignment","expected":[11,"lower",2],"passed":false},{"actual":[45,"lower",3],"check":"partial repair variant: phase alignment","expected":[45,"upper",3],"passed":false},{"actual":[0,"upper",2],"check":"boundary control","expected":[0,"upper",2],"passed":true},{"actual":[5,"upper",2],"check":"boundary control","expected":[5,"upper",2],"passed":true},{"actual":[1,"upper",3],"check":"normal control","expected":[1,"upper",3],"passed":true},{"actual":[10,"upper",2],"check":"normal control","expected":[10,"upper",2],"passed":true},{"actual":null,"check":"normal control","expected":null,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: phase alignment\", \"actual\": [0, \"lower\", 3], \"expected\": [0, \"upper\", 3], \"passed\": false}, {\"check\": \"regression variant: phase alignment\", \"actual\": [13, \"lower\", 2], \"expected\": [11, \"lower\", 2], \"passed\": false}, {\"check\": \"partial repair probe: phase alignment\", \"actual\": [12, \"upper\", 2], \"expected\": [11, \"lower\", 2], \"passed\": false}, {\"check\": \"partial repair variant: phase alignment\", \"actual\": [45, \"lower\", 3], \"expected\": [45, \"upper\", 3], \"passed\": false}, {\"check\": \"boundary control\", \"actual\": [0, \"upper\", 2], \"expected\": [0, \"upper\", 2], \"passed\": true}, {\"check\": \"boundary control\", \"actual\": [5, \"upper\", 2], \"expected\": [5, \"upper\", 2], \"passed\": true}, {\"check\": \"normal control\", \"actual\": [1, \"upper\", 3], \"expected\": [1, \"upper\", 3], \"passed\": true}, {\"check\": \"normal control\", \"actual\": [10, \"upper\", 2], \"expected\": [10, \"upper\", 2], \"passed\": true}, {\"check\": \"normal control\", \"actual\": null, \"expected\": null, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":43.018,"exit_code":1,"observations":[{"actual":[1,"upper",3],"check":"regression: phase alignment","expected":[0,"upper",3],"passed":false},{"actual":[15,"upper",2],"check":"regression variant: phase alignment","expected":[11,"lower",2],"passed":false},{"actual":[12,"lower",2],"check":"partial repair probe: phase alignment","expected":[11,"lower",2],"passed":false},{"actual":[46,"upper",3],"check":"partial repair variant: phase alignment","expected":[45,"upper",3],"passed":false},{"actual":[0,"upper",2],"check":"boundary control","expected":[0,"upper",2],"passed":true},{"actual":[5,"upper",2],"check":"boundary control","expected":[5,"upper",2],"passed":true},{"actual":[1,"upper",3],"check":"normal control","expected":[1,"upper",3],"passed":true},{"actual":[10,"upper",2],"check":"normal control","expected":[10,"upper",2],"passed":true},{"actual":null,"check":"normal control","expected":null,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: phase alignment\", \"actual\": [1, \"upper\", 3], \"expected\": [0, \"upper\", 3], \"passed\": false}, {\"check\": \"regression variant: phase alignment\", \"actual\": [15, \"upper\", 2], \"expected\": [11, \"lower\", 2], \"passed\": false}, {\"check\": \"partial repair probe: phase alignment\", \"actual\": [12, \"lower\", 2], \"expected\": [11, \"lower\", 2], \"passed\": false}, {\"check\": \"partial repair variant: phase alignment\", \"actual\": [46, \"upper\", 3], \"expected\": [45, \"upper\", 3], \"passed\": false}, {\"check\": \"boundary control\", \"actual\": [0, \"upper\", 2], \"expected\": [0, \"upper\", 2], \"passed\": true}, {\"check\": \"boundary control\", \"actual\": [5, \"upper\", 2], \"expected\": [5, \"upper\", 2], \"passed\": true}, {\"check\": \"normal control\", \"actual\": [1, \"upper\", 3], \"expected\": [1, \"upper\", 3], \"passed\": true}, {\"check\": \"normal control\", \"actual\": [10, \"upper\", 2], \"expected\": [10, \"upper\", 2], \"passed\": true}, {\"check\": \"normal control\", \"actual\": null, \"expected\": null, \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":77.478,"exit_code":0,"observations":[{"actual":[0,"upper",3],"check":"regression: phase alignment","expected":[0,"upper",3],"passed":true},{"actual":[11,"lower",2],"check":"regression variant: phase alignment","expected":[11,"lower",2],"passed":true},{"actual":[11,"lower",2],"check":"partial repair probe: phase alignment","expected":[11,"lower",2],"passed":true},{"actual":[45,"upper",3],"check":"partial repair variant: phase alignment","expected":[45,"upper",3],"passed":true},{"actual":[0,"upper",2],"check":"boundary control","expected":[0,"upper",2],"passed":true},{"actual":[5,"upper",2],"check":"boundary control","expected":[5,"upper",2],"passed":true},{"actual":[1,"upper",3],"check":"normal control","expected":[1,"upper",3],"passed":true},{"actual":[10,"upper",2],"check":"normal control","expected":[10,"upper",2],"passed":true},{"actual":null,"check":"normal control","expected":null,"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: phase alignment\", \"actual\": [0, \"upper\", 3], \"expected\": [0, \"upper\", 3], \"passed\": true}, {\"check\": \"regression variant: phase alignment\", \"actual\": [11, \"lower\", 2], \"expected\": [11, \"lower\", 2], \"passed\": true}, {\"check\": \"partial repair probe: phase alignment\", \"actual\": [11, \"lower\", 2], \"expected\": [11, \"lower\", 2], \"passed\": true}, {\"check\": \"partial repair variant: phase alignment\", \"actual\": [45, \"upper\", 3], \"expected\": [45, \"upper\", 3], \"passed\": true}, {\"check\": \"boundary control\", \"actual\": [0, \"upper\", 2], \"expected\": [0, \"upper\", 2], \"passed\": true}, {\"check\": \"boundary control\", \"actual\": [5, \"upper\", 2], \"expected\": [5, \"upper\", 2], \"passed\": true}, {\"check\": \"normal control\", \"actual\": [1, \"upper\", 3], \"expected\": [1, \"upper\", 3], \"passed\": true}, {\"check\": \"normal control\", \"actual\": [10, \"upper\", 2], \"expected\": [10, \"upper\", 2], \"passed\": true}, {\"check\": \"normal control\", \"actual\": null, \"expected\": null, \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}