{"abstract":"Field counts are wrong whenever the cadence phase is not zero.","category":"Broadcast timecode arithmetic","checks":7,"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":"The inverted count table swaps two- and three-field frames.","family":"w2-broadcast-timecode-arithmetic-pulldown-film-to-video-field-count-lookup","id":"FA-78556","implementations":{"attempt":{"sha256":"fcfc7592ae4cf9ad53d83533d39988e7d35b5717eed7305922cfb9197f934dc2","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=[3,2,3,2][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: field count lookup', [0, 1], [0, 'upper', 3]), ('regression variant: field count lookup', [10, 1], [12, 'lower', 3]), ('partial repair probe: field count lookup', [3, 0], [3, 'lower', 3]), ('partial repair variant: field count lookup', [34, 2], [42, 'lower', 2]), ('normal control', [-3, 2], None), ('normal control', [-2, 3], None), ('normal control', [-2, 1], None)], [('regression: field count lookup', [2, 3], [2, 'lower', 3]), ('regression variant: field count lookup', [36, 1], [45, 'upper', 3]), ('partial repair probe: field count lookup', [4, 0], [5, 'upper', 2]), ('partial repair variant: field count lookup', [9, 3], [11, 'lower', 2]), ('normal control', [-5, 1], None), ('normal control', [-1, 1], None), ('normal control', [-4, 1], None)], [('regression: field count lookup', [9, 1], [11, 'lower', 2]), ('regression variant: field count lookup', [38, 3], [47, 'lower', 3]), ('partial repair probe: field count lookup', [0, 1], [0, 'upper', 3]), ('partial repair variant: field count lookup', [10, 1], [12, 'lower', 3]), ('normal control', [-2, 2], None), ('normal control', [-1, 0], None), ('normal control', [-2, 0], None)], [('regression: field count lookup', [35, 1], [44, 'upper', 2]), ('regression variant: field count lookup', [1, 3], [1, 'lower', 2]), ('partial repair probe: field count lookup', [2, 3], [2, 'lower', 3]), ('partial repair variant: field count lookup', [22, 2], [27, 'lower', 2]), ('normal control', [-1, 2], None), ('normal control', [-4, 2], None), ('normal control', [-2, 3], None)], [('regression: field count lookup', [9, 3], [11, 'lower', 2]), ('regression variant: field count lookup', [30, 3], [37, 'lower', 3]), ('partial repair probe: field count lookup', [8, 0], [10, 'upper', 2]), ('partial repair variant: field count lookup', [26, 2], [32, 'lower', 2]), ('normal control', [-2, 1], None), ('normal control', [-3, 0], None), ('normal control', [-1, 1], None)]]\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":"ad5cc010f830d75f047ecbae9bc60163cbafd67b20a6802907e83ce0d463f699","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][n%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: field count lookup', [0, 1], [0, 'upper', 3]), ('regression variant: field count lookup', [10, 1], [12, 'lower', 3]), ('partial repair probe: field count lookup', [3, 0], [3, 'lower', 3]), ('partial repair variant: field count lookup', [34, 2], [42, 'lower', 2]), ('normal control', [-3, 2], None), ('normal control', [-2, 3], None), ('normal control', [-2, 1], None)], [('regression: field count lookup', [2, 3], [2, 'lower', 3]), ('regression variant: field count lookup', [36, 1], [45, 'upper', 3]), ('partial repair probe: field count lookup', [4, 0], [5, 'upper', 2]), ('partial repair variant: field count lookup', [9, 3], [11, 'lower', 2]), ('normal control', [-5, 1], None), ('normal control', [-1, 1], None), ('normal control', [-4, 1], None)], [('regression: field count lookup', [9, 1], [11, 'lower', 2]), ('regression variant: field count lookup', [38, 3], [47, 'lower', 3]), ('partial repair probe: field count lookup', [0, 1], [0, 'upper', 3]), ('partial repair variant: field count lookup', [10, 1], [12, 'lower', 3]), ('normal control', [-2, 2], None), ('normal control', [-1, 0], None), ('normal control', [-2, 0], None)], [('regression: field count lookup', [35, 1], [44, 'upper', 2]), ('regression variant: field count lookup', [1, 3], [1, 'lower', 2]), ('partial repair probe: field count lookup', [2, 3], [2, 'lower', 3]), ('partial repair variant: field count lookup', [22, 2], [27, 'lower', 2]), ('normal control', [-1, 2], None), ('normal control', [-4, 2], None), ('normal control', [-2, 3], None)], [('regression: field count lookup', [9, 3], [11, 'lower', 2]), ('regression variant: field count lookup', [30, 3], [37, 'lower', 3]), ('partial repair probe: field count lookup', [8, 0], [10, 'upper', 2]), ('partial repair variant: field count lookup', [26, 2], [32, 'lower', 2]), ('normal control', [-2, 1], None), ('normal control', [-3, 0], None), ('normal control', [-1, 1], None)]]\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":"fc430c535bbbf7bafc122a35fb4fd7e9b1c96773334c5c4ad695fc298557d320","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: field count lookup', [0, 1], [0, 'upper', 3]), ('regression variant: field count lookup', [10, 1], [12, 'lower', 3]), ('partial repair probe: field count lookup', [3, 0], [3, 'lower', 3]), ('partial repair variant: field count lookup', [34, 2], [42, 'lower', 2]), ('normal control', [-3, 2], None), ('normal control', [-2, 3], None), ('normal control', [-2, 1], None)], [('regression: field count lookup', [2, 3], [2, 'lower', 3]), ('regression variant: field count lookup', [36, 1], [45, 'upper', 3]), ('partial repair probe: field count lookup', [4, 0], [5, 'upper', 2]), ('partial repair variant: field count lookup', [9, 3], [11, 'lower', 2]), ('normal control', [-5, 1], None), ('normal control', [-1, 1], None), ('normal control', [-4, 1], None)], [('regression: field count lookup', [9, 1], [11, 'lower', 2]), ('regression variant: field count lookup', [38, 3], [47, 'lower', 3]), ('partial repair probe: field count lookup', [0, 1], [0, 'upper', 3]), ('partial repair variant: field count lookup', [10, 1], [12, 'lower', 3]), ('normal control', [-2, 2], None), ('normal control', [-1, 0], None), ('normal control', [-2, 0], None)], [('regression: field count lookup', [35, 1], [44, 'upper', 2]), ('regression variant: field count lookup', [1, 3], [1, 'lower', 2]), ('partial repair probe: field count lookup', [2, 3], [2, 'lower', 3]), ('partial repair variant: field count lookup', [22, 2], [27, 'lower', 2]), ('normal control', [-1, 2], None), ('normal control', [-4, 2], None), ('normal control', [-2, 3], None)], [('regression: field count lookup', [9, 3], [11, 'lower', 2]), ('regression variant: field count lookup', [30, 3], [37, 'lower', 3]), ('partial repair probe: field count lookup', [8, 0], [10, 'upper', 2]), ('partial repair variant: field count lookup', [26, 2], [32, 'lower', 2]), ('normal control', [-2, 1], None), ('normal control', [-3, 0], None), ('normal control', [-1, 1], None)]]\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-field-count-lookup","generated_at":"2026-09-29T14:49:36.593849+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":"Look up the count at the phased cadence position.","root_cause":"The count is looked up from the film index without the phase.","sha256":"504e97ba28ea904cfebcc767c78f20b21bf43863ec828b091e1ff2cb2271f7c3","title":"2:3 pulldown film frame placement: field count lookup · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":39.808,"exit_code":1,"observations":[{"actual":[0,"upper",2],"check":"regression: field count lookup","expected":[0,"upper",3],"passed":false},{"actual":[12,"lower",2],"check":"regression variant: field count lookup","expected":[12,"lower",3],"passed":false},{"actual":[3,"lower",2],"check":"partial repair probe: field count lookup","expected":[3,"lower",3],"passed":false},{"actual":[42,"lower",3],"check":"partial repair variant: field count lookup","expected":[42,"lower",2],"passed":false},{"actual":null,"check":"normal control","expected":null,"passed":true},{"actual":null,"check":"normal control","expected":null,"passed":true},{"actual":null,"check":"normal control","expected":null,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: field count lookup\", \"actual\": [0, \"upper\", 2], \"expected\": [0, \"upper\", 3], \"passed\": false}, {\"check\": \"regression variant: field count lookup\", \"actual\": [12, \"lower\", 2], \"expected\": [12, \"lower\", 3], \"passed\": false}, {\"check\": \"partial repair probe: field count lookup\", \"actual\": [3, \"lower\", 2], \"expected\": [3, \"lower\", 3], \"passed\": false}, {\"check\": \"partial repair variant: field count lookup\", \"actual\": [42, \"lower\", 3], \"expected\": [42, \"lower\", 2], \"passed\": false}, {\"check\": \"normal control\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"normal control\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"normal control\", \"actual\": null, \"expected\": null, \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":39.75,"exit_code":1,"observations":[{"actual":[0,"upper",2],"check":"regression: field count lookup","expected":[0,"upper",3],"passed":false},{"actual":[12,"lower",2],"check":"regression variant: field count lookup","expected":[12,"lower",3],"passed":false},{"actual":[3,"lower",3],"check":"partial repair probe: field count lookup","expected":[3,"lower",3],"passed":true},{"actual":[42,"lower",2],"check":"partial repair variant: field count lookup","expected":[42,"lower",2],"passed":true},{"actual":null,"check":"normal control","expected":null,"passed":true},{"actual":null,"check":"normal control","expected":null,"passed":true},{"actual":null,"check":"normal control","expected":null,"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: field count lookup\", \"actual\": [0, \"upper\", 2], \"expected\": [0, \"upper\", 3], \"passed\": false}, {\"check\": \"regression variant: field count lookup\", \"actual\": [12, \"lower\", 2], \"expected\": [12, \"lower\", 3], \"passed\": false}, {\"check\": \"partial repair probe: field count lookup\", \"actual\": [3, \"lower\", 3], \"expected\": [3, \"lower\", 3], \"passed\": true}, {\"check\": \"partial repair variant: field count lookup\", \"actual\": [42, \"lower\", 2], \"expected\": [42, \"lower\", 2], \"passed\": true}, {\"check\": \"normal control\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"normal control\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"normal control\", \"actual\": null, \"expected\": null, \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":42.087,"exit_code":0,"observations":[{"actual":[0,"upper",3],"check":"regression: field count lookup","expected":[0,"upper",3],"passed":true},{"actual":[12,"lower",3],"check":"regression variant: field count lookup","expected":[12,"lower",3],"passed":true},{"actual":[3,"lower",3],"check":"partial repair probe: field count lookup","expected":[3,"lower",3],"passed":true},{"actual":[42,"lower",2],"check":"partial repair variant: field count lookup","expected":[42,"lower",2],"passed":true},{"actual":null,"check":"normal control","expected":null,"passed":true},{"actual":null,"check":"normal control","expected":null,"passed":true},{"actual":null,"check":"normal control","expected":null,"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: field count lookup\", \"actual\": [0, \"upper\", 3], \"expected\": [0, \"upper\", 3], \"passed\": true}, {\"check\": \"regression variant: field count lookup\", \"actual\": [12, \"lower\", 3], \"expected\": [12, \"lower\", 3], \"passed\": true}, {\"check\": \"partial repair probe: field count lookup\", \"actual\": [3, \"lower\", 3], \"expected\": [3, \"lower\", 3], \"passed\": true}, {\"check\": \"partial repair variant: field count lookup\", \"actual\": [42, \"lower\", 2], \"expected\": [42, \"lower\", 2], \"passed\": true}, {\"check\": \"normal control\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"normal control\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"normal control\", \"actual\": null, \"expected\": null, \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}