{"abstract":"B-frames are placed as if every film frame had two fields.","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].","contract_signature":"n, phase","evaluation_group":"w2-broadcast-timecode-arithmetic-pulldown-film-to-video","failed_approach":"The 3:2 offsets describe a different cadence starting with a three-field frame.","family":"w2-broadcast-timecode-arithmetic-pulldown-film-to-video-field-offset-table","id":"FA-78546","implementations":{"attempt":{"sha256":"a470d1e066533a0d9000f1fdc99b544db00a2b226bb1b92b97de2deaf980cd08","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)+[0,3,5,8][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 offset table', [3, 0], [3, 'lower', 3]), ('regression variant: field offset table', [10, 1], [12, 'lower', 3]), ('partial repair probe: field offset table', [9, 1], [11, 'lower', 2]), ('partial repair variant: field offset table', [21, 2], [26, 'upper', 3]), ('boundary control', [0, 0], [0, 'upper', 2]), ('boundary control', [4, 0], [5, 'upper', 2]), ('normal control', [0, 1], [0, 'upper', 3]), ('normal control', [8, 0], [10, 'upper', 2]), ('normal control', [36, 1], [45, 'upper', 3])], [('regression: field offset table', [2, 3], [2, 'lower', 3]), ('regression variant: field offset table', [22, 2], [27, 'lower', 2]), ('partial repair probe: field offset table', [35, 1], [44, 'upper', 2]), ('partial repair variant: field offset table', [19, 2], [23, 'lower', 3]), ('boundary control', [4, 0], [5, 'upper', 2]), ('boundary control', [0, 1], [0, 'upper', 3]), ('normal control', [-6, 0], None), ('normal control', [-2, 3], None), ('normal control', [-3, 1], None)], [('regression: field offset table', [9, 1], [11, 'lower', 2]), ('regression variant: field offset table', [26, 2], [32, 'lower', 2]), ('partial repair probe: field offset table', [9, 3], [11, 'lower', 2]), ('partial repair variant: field offset table', [17, 1], [21, 'lower', 2]), ('boundary control', [0, 1], [0, 'upper', 3]), ('boundary control', [0, 0], [0, 'upper', 2]), ('normal control', [-6, 1], None), ('normal control', [-3, 0], None), ('normal control', [8, 3], [10, 'upper', 3])], [('regression: field offset table', [34, 2], [42, 'lower', 2]), ('regression variant: field offset table', [38, 3], [47, 'lower', 3]), ('partial repair probe: field offset table', [1, 3], [1, 'lower', 2]), ('partial repair variant: field offset table', [5, 2], [6, 'upper', 3]), ('boundary control', [0, 0], [0, 'upper', 2]), ('boundary control', [4, 0], [5, 'upper', 2]), ('normal control', [-1, 1], None), ('normal control', [36, 0], [45, 'upper', 2]), ('normal control', [-3, 3], None)], [('regression: field offset table', [9, 3], [11, 'lower', 2]), ('regression variant: field offset table', [1, 3], [1, 'lower', 2]), ('partial repair probe: field offset table', [3, 2], [3, 'lower', 3]), ('partial repair variant: field offset table', [7, 2], [8, 'lower', 3]), ('boundary control', [4, 0], [5, 'upper', 2]), ('boundary control', [0, 1], [0, 'upper', 3]), ('normal control', [28, 0], [35, 'upper', 2]), ('normal control', [28, 3], [35, 'upper', 3]), ('normal control', [24, 1], [30, 'upper', 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":"435b2d14844165f514ec96f9cfdbf010d60d6d68de40e6f551d7305ab41a09a3","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)+[0,2,4,6][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 offset table', [3, 0], [3, 'lower', 3]), ('regression variant: field offset table', [10, 1], [12, 'lower', 3]), ('partial repair probe: field offset table', [9, 1], [11, 'lower', 2]), ('partial repair variant: field offset table', [21, 2], [26, 'upper', 3]), ('boundary control', [0, 0], [0, 'upper', 2]), ('boundary control', [4, 0], [5, 'upper', 2]), ('normal control', [0, 1], [0, 'upper', 3]), ('normal control', [8, 0], [10, 'upper', 2]), ('normal control', [36, 1], [45, 'upper', 3])], [('regression: field offset table', [2, 3], [2, 'lower', 3]), ('regression variant: field offset table', [22, 2], [27, 'lower', 2]), ('partial repair probe: field offset table', [35, 1], [44, 'upper', 2]), ('partial repair variant: field offset table', [19, 2], [23, 'lower', 3]), ('boundary control', [4, 0], [5, 'upper', 2]), ('boundary control', [0, 1], [0, 'upper', 3]), ('normal control', [-6, 0], None), ('normal control', [-2, 3], None), ('normal control', [-3, 1], None)], [('regression: field offset table', [9, 1], [11, 'lower', 2]), ('regression variant: field offset table', [26, 2], [32, 'lower', 2]), ('partial repair probe: field offset table', [9, 3], [11, 'lower', 2]), ('partial repair variant: field offset table', [17, 1], [21, 'lower', 2]), ('boundary control', [0, 1], [0, 'upper', 3]), ('boundary control', [0, 0], [0, 'upper', 2]), ('normal control', [-6, 1], None), ('normal control', [-3, 0], None), ('normal control', [8, 3], [10, 'upper', 3])], [('regression: field offset table', [34, 2], [42, 'lower', 2]), ('regression variant: field offset table', [38, 3], [47, 'lower', 3]), ('partial repair probe: field offset table', [1, 3], [1, 'lower', 2]), ('partial repair variant: field offset table', [5, 2], [6, 'upper', 3]), ('boundary control', [0, 0], [0, 'upper', 2]), ('boundary control', [4, 0], [5, 'upper', 2]), ('normal control', [-1, 1], None), ('normal control', [36, 0], [45, 'upper', 2]), ('normal control', [-3, 3], None)], [('regression: field offset table', [9, 3], [11, 'lower', 2]), ('regression variant: field offset table', [1, 3], [1, 'lower', 2]), ('partial repair probe: field offset table', [3, 2], [3, 'lower', 3]), ('partial repair variant: field offset table', [7, 2], [8, 'lower', 3]), ('boundary control', [4, 0], [5, 'upper', 2]), ('boundary control', [0, 1], [0, 'upper', 3]), ('normal control', [28, 0], [35, 'upper', 2]), ('normal control', [28, 3], [35, 'upper', 3]), ('normal control', [24, 1], [30, 'upper', 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-field-offset-table","generated_at":"2026-09-29T14:49:36.300938+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.","root_cause":"The in-group field offsets ignore the three-field frames.","sha256":"b8dbf885476e51cb6cd57c141df9d567e4203814f53c90a79f3021e65c2426d5","title":"2:3 pulldown film frame placement: field offset table · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":43.343,"exit_code":1,"observations":[{"actual":[4,"upper",3],"check":"regression: field offset table","expected":[3,"lower",3],"passed":false},{"actual":[12,"lower",3],"check":"regression variant: field offset table","expected":[12,"lower",3],"passed":true},{"actual":[11,"upper",2],"check":"partial repair probe: field offset table","expected":[11,"lower",2],"passed":false},{"actual":[26,"lower",3],"check":"partial repair variant: field offset table","expected":[26,"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":[0,"upper",3],"check":"normal control","expected":[0,"upper",3],"passed":true},{"actual":[10,"upper",2],"check":"normal control","expected":[10,"upper",2],"passed":true},{"actual":[45,"upper",3],"check":"normal control","expected":[45,"upper",3],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: field offset table\", \"actual\": [4, \"upper\", 3], \"expected\": [3, \"lower\", 3], \"passed\": false}, {\"check\": \"regression variant: field offset table\", \"actual\": [12, \"lower\", 3], \"expected\": [12, \"lower\", 3], \"passed\": true}, {\"check\": \"partial repair probe: field offset table\", \"actual\": [11, \"upper\", 2], \"expected\": [11, \"lower\", 2], \"passed\": false}, {\"check\": \"partial repair variant: field offset table\", \"actual\": [26, \"lower\", 3], \"expected\": [26, \"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\": [0, \"upper\", 3], \"expected\": [0, \"upper\", 3], \"passed\": true}, {\"check\": \"normal control\", \"actual\": [10, \"upper\", 2], \"expected\": [10, \"upper\", 2], \"passed\": true}, {\"check\": \"normal control\", \"actual\": [45, \"upper\", 3], \"expected\": [45, \"upper\", 3], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":40.625,"exit_code":1,"observations":[{"actual":[3,"upper",3],"check":"regression: field offset table","expected":[3,"lower",3],"passed":false},{"actual":[12,"upper",3],"check":"regression variant: field offset table","expected":[12,"lower",3],"passed":false},{"actual":[11,"upper",2],"check":"partial repair probe: field offset table","expected":[11,"lower",2],"passed":false},{"actual":[26,"upper",3],"check":"partial repair variant: field offset table","expected":[26,"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":[0,"upper",3],"check":"normal control","expected":[0,"upper",3],"passed":true},{"actual":[10,"upper",2],"check":"normal control","expected":[10,"upper",2],"passed":true},{"actual":[45,"upper",3],"check":"normal control","expected":[45,"upper",3],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: field offset table\", \"actual\": [3, \"upper\", 3], \"expected\": [3, \"lower\", 3], \"passed\": false}, {\"check\": \"regression variant: field offset table\", \"actual\": [12, \"upper\", 3], \"expected\": [12, \"lower\", 3], \"passed\": false}, {\"check\": \"partial repair probe: field offset table\", \"actual\": [11, \"upper\", 2], \"expected\": [11, \"lower\", 2], \"passed\": false}, {\"check\": \"partial repair variant: field offset table\", \"actual\": [26, \"upper\", 3], \"expected\": [26, \"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\": [0, \"upper\", 3], \"expected\": [0, \"upper\", 3], \"passed\": true}, {\"check\": \"normal control\", \"actual\": [10, \"upper\", 2], \"expected\": [10, \"upper\", 2], \"passed\": true}, {\"check\": \"normal control\", \"actual\": [45, \"upper\", 3], \"expected\": [45, \"upper\", 3], \"passed\": true}], \"passed\": false}\n"}},"member_only":{"stages":["fixed"],"fields":["implementations.fixed","verification.fixed","harness","repair"],"note":"The verified repair, its recorded checks, the repair description, and the scoring harness are available to members."}}