{"abstract":"Empty captions with unknown start time are emitted when the first caption flips on.","category":"Subtitle cue timing","checks":7,"contract":"Commands [frame,cmd] at integer fps (time = frame*1000//fps). TEXT:x appends x to the non-displayed memory; ENM erases non-displayed memory; EOC swaps displayed and non-displayed memories; EDM erases displayed memory. Whenever non-empty displayed text is replaced (EOC) or erased (EDM), emit [shown_since_ms, now_ms, text].","contract_signature":"events, fps","evaluation_group":"w2-subtitle-cue-timing-pop-on-caption-buffers","failed_approach":"Guarding on a known start still emits empty captions after a displayed erase.","family":"w2-subtitle-cue-timing-pop-on-caption-buffers-flip-emission-guard","id":"FA-78256","implementations":{"attempt":{"sha256":"d460956c3a90cea64429fb7f22040a3f7cd1d0fa2eade56d090bdf45a7d8483f","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(events, fps):\n    shown=''\n    hidden=''\n    since=None\n    out=[]\n    for frame,cmd in events:\n        t=frame*1000//fps\n        if cmd.startswith('TEXT:'):\n            hidden+=cmd[5:]\n        elif cmd=='ENM':\n            hidden=''\n        elif cmd=='EOC':\n            if since is not None:\n                out.append([since,t,shown])\n            shown,hidden=hidden,shown\n            since=t\n        elif cmd=='EDM':\n            if shown: out.append([since,t,shown])\n            shown=''\n    return out\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('regression: flip emission guard', [[[0, 'TEXT:Hi'], [30, 'EOC'], [60, 'EDM']], 30], [[1000, 2000, 'Hi']]), ('regression variant: flip emission guard', [[[30, 'TEXT:Bye'], [37, 'EOC'], [52, 'EDM'], [52, 'ENM'], [67, 'EDM']], 30], [[1233, 1733, 'Bye']]), ('partial repair probe: flip emission guard', [[[3, 'EOC'], [32, 'EOC'], [77, 'TEXT:Bye']], 25], []), ('partial repair variant: flip emission guard', [[[3, 'TEXT:Hi'], [48, 'EOC'], [49, 'EOC'], [49, 'TEXT:Hi'], [94, 'TEXT:Bye'], [123, 'EOC'], [130, 'EDM']], 25], [[1920, 1960, 'Hi'], [4920, 5200, 'HiHiBye']]), ('normal control', [[[0, 'EDM'], [7, 'TEXT: there'], [37, 'TEXT: there']], 29], []), ('normal control', [[[30, 'EDM'], [60, 'TEXT: there'], [90, 'TEXT:Bye']], 24], []), ('normal control', [[[3, 'EDM'], [32, 'TEXT:Bye'], [77, 'TEXT:Bye'], [106, 'TEXT:Hi'], [151, 'TEXT:Hi']], 29], [])], [('regression: flip emission guard', [[[0, 'TEXT:A'], [10, 'EOC'], [20, 'TEXT:B'], [40, 'EOC'], [50, 'EOC']], 25], [[400, 1600, 'A'], [1600, 2000, 'B']]), ('regression variant: flip emission guard', [[[0, 'EOC'], [30, 'TEXT:Bye'], [31, 'EOC'], [46, 'EOC'], [91, 'TEXT:Hi'], [92, 'TEXT: there'], [99, 'EDM'], [129, 'ENM']], 30], [[1033, 1533, 'Bye']]), ('partial repair probe: flip emission guard', [[[0, 'TEXT:Bye'], [1, 'EDM'], [31, 'TEXT: there'], [61, 'ENM'], [68, 'EOC'], [98, 'EOC'], [113, 'TEXT:Bye']], 25], []), ('partial repair variant: flip emission guard', [[[0, 'EOC'], [7, 'ENM'], [52, 'EOC'], [81, 'TEXT:Hi']], 30], []), ('normal control', [[[0, 'EDM'], [15, 'TEXT:Bye']], 29], []), ('normal control', [[[3, 'TEXT: there'], [32, 'EDM'], [32, 'TEXT: there']], 25], []), ('normal control', [[[0, 'EDM'], [29, 'TEXT: there'], [44, 'TEXT: there'], [89, 'TEXT:Bye'], [134, 'TEXT: there']], 30], [])], [('regression: flip emission guard', [[[0, 'EOC'], [5, 'EDM']], 30], []), ('regression variant: flip emission guard', [[[30, 'TEXT:Hi'], [31, 'TEXT: there'], [61, 'EDM'], [106, 'TEXT: there'], [121, 'ENM'], [136, 'TEXT:Hi'], [166, 'EOC']], 24], []), ('partial repair probe: flip emission guard', [[[0, 'EOC'], [7, 'EDM'], [14, 'EOC'], [59, 'EOC'], [104, 'EOC'], [133, 'EOC'], [162, 'EOC'], [207, 'EOC']], 25], []), ('partial repair variant: flip emission guard', [[[0, 'EOC'], [1, 'EOC'], [30, 'ENM'], [37, 'TEXT:Bye']], 30], []), ('normal control', [[[0, 'ENM'], [29, 'TEXT:Bye'], [59, 'TEXT: there']], 25], []), ('normal control', [[[3, 'TEXT: there'], [48, 'TEXT:Hi'], [49, 'TEXT:Bye'], [78, 'TEXT:Hi']], 29], []), ('normal control', [[[3, 'TEXT:Bye'], [18, 'TEXT:Bye'], [25, 'TEXT:Bye'], [40, 'TEXT: there']], 30], [])], [('regression: flip emission guard', [[[30, 'EOC'], [30, 'TEXT:Hi'], [37, 'ENM']], 24], []), ('regression variant: flip emission guard', [[[30, 'TEXT: there'], [30, 'EOC'], [59, 'ENM']], 30], []), ('partial repair probe: flip emission guard', [[[30, 'EOC'], [59, 'EOC'], [60, 'TEXT: there'], [89, 'TEXT: there'], [96, 'ENM'], [96, 'TEXT:Bye'], [96, 'TEXT:Bye'], [96, 'TEXT: there']], 30], []), ('partial repair variant: flip emission guard', [[[30, 'EOC'], [31, 'ENM'], [32, 'EOC']], 29], []), ('normal control', [[[0, 'ENM'], [7, 'TEXT: there'], [37, 'EDM']], 25], []), ('normal control', [[[3, 'ENM'], [10, 'TEXT:Bye']], 25], []), ('normal control', [[[0, 'TEXT: there'], [7, 'TEXT:Hi'], [22, 'TEXT:Bye']], 29], [])], [('regression: flip emission guard', [[[0, 'EOC'], [7, 'TEXT:Bye'], [52, 'EDM'], [59, 'TEXT:Bye'], [74, 'EOC']], 24], []), ('regression variant: flip emission guard', [[[30, 'EDM'], [30, 'EOC'], [60, 'ENM'], [89, 'ENM']], 25], []), ('partial repair probe: flip emission guard', [[[0, 'EOC'], [29, 'EOC'], [29, 'ENM'], [36, 'TEXT: there'], [37, 'TEXT: there'], [38, 'EOC']], 25], []), ('partial repair variant: flip emission guard', [[[0, 'TEXT:Bye'], [7, 'EOC'], [14, 'EDM'], [43, 'ENM'], [88, 'EDM'], [95, 'EOC'], [95, 'EOC'], [125, 'TEXT:Bye']], 24], [[291, 583, 'Bye']]), ('normal control', [[[0, 'TEXT:Bye'], [30, 'TEXT: there'], [37, 'ENM'], [82, 'EDM'], [127, 'TEXT:Hi'], [128, 'TEXT: there'], [158, 'TEXT:Hi'], [187, 'TEXT: there']], 29], []), ('normal control', [[[3, 'TEXT:Bye'], [18, 'ENM']], 24], []), ('normal control', [[[3, 'TEXT: there'], [33, 'TEXT:Bye'], [62, 'EDM']], 29], [])]]\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":"e78391188676180414c77d9bea2742912f2c709237d648aeb6049dd6bd06ac71","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(events, fps):\n    shown=''\n    hidden=''\n    since=None\n    out=[]\n    for frame,cmd in events:\n        t=frame*1000//fps\n        if cmd.startswith('TEXT:'):\n            hidden+=cmd[5:]\n        elif cmd=='ENM':\n            hidden=''\n        elif cmd=='EOC':\n            if True:\n                out.append([since,t,shown])\n            shown,hidden=hidden,shown\n            since=t\n        elif cmd=='EDM':\n            if shown: out.append([since,t,shown])\n            shown=''\n    return out\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('regression: flip emission guard', [[[0, 'TEXT:Hi'], [30, 'EOC'], [60, 'EDM']], 30], [[1000, 2000, 'Hi']]), ('regression variant: flip emission guard', [[[30, 'TEXT:Bye'], [37, 'EOC'], [52, 'EDM'], [52, 'ENM'], [67, 'EDM']], 30], [[1233, 1733, 'Bye']]), ('partial repair probe: flip emission guard', [[[3, 'EOC'], [32, 'EOC'], [77, 'TEXT:Bye']], 25], []), ('partial repair variant: flip emission guard', [[[3, 'TEXT:Hi'], [48, 'EOC'], [49, 'EOC'], [49, 'TEXT:Hi'], [94, 'TEXT:Bye'], [123, 'EOC'], [130, 'EDM']], 25], [[1920, 1960, 'Hi'], [4920, 5200, 'HiHiBye']]), ('normal control', [[[0, 'EDM'], [7, 'TEXT: there'], [37, 'TEXT: there']], 29], []), ('normal control', [[[30, 'EDM'], [60, 'TEXT: there'], [90, 'TEXT:Bye']], 24], []), ('normal control', [[[3, 'EDM'], [32, 'TEXT:Bye'], [77, 'TEXT:Bye'], [106, 'TEXT:Hi'], [151, 'TEXT:Hi']], 29], [])], [('regression: flip emission guard', [[[0, 'TEXT:A'], [10, 'EOC'], [20, 'TEXT:B'], [40, 'EOC'], [50, 'EOC']], 25], [[400, 1600, 'A'], [1600, 2000, 'B']]), ('regression variant: flip emission guard', [[[0, 'EOC'], [30, 'TEXT:Bye'], [31, 'EOC'], [46, 'EOC'], [91, 'TEXT:Hi'], [92, 'TEXT: there'], [99, 'EDM'], [129, 'ENM']], 30], [[1033, 1533, 'Bye']]), ('partial repair probe: flip emission guard', [[[0, 'TEXT:Bye'], [1, 'EDM'], [31, 'TEXT: there'], [61, 'ENM'], [68, 'EOC'], [98, 'EOC'], [113, 'TEXT:Bye']], 25], []), ('partial repair variant: flip emission guard', [[[0, 'EOC'], [7, 'ENM'], [52, 'EOC'], [81, 'TEXT:Hi']], 30], []), ('normal control', [[[0, 'EDM'], [15, 'TEXT:Bye']], 29], []), ('normal control', [[[3, 'TEXT: there'], [32, 'EDM'], [32, 'TEXT: there']], 25], []), ('normal control', [[[0, 'EDM'], [29, 'TEXT: there'], [44, 'TEXT: there'], [89, 'TEXT:Bye'], [134, 'TEXT: there']], 30], [])], [('regression: flip emission guard', [[[0, 'EOC'], [5, 'EDM']], 30], []), ('regression variant: flip emission guard', [[[30, 'TEXT:Hi'], [31, 'TEXT: there'], [61, 'EDM'], [106, 'TEXT: there'], [121, 'ENM'], [136, 'TEXT:Hi'], [166, 'EOC']], 24], []), ('partial repair probe: flip emission guard', [[[0, 'EOC'], [7, 'EDM'], [14, 'EOC'], [59, 'EOC'], [104, 'EOC'], [133, 'EOC'], [162, 'EOC'], [207, 'EOC']], 25], []), ('partial repair variant: flip emission guard', [[[0, 'EOC'], [1, 'EOC'], [30, 'ENM'], [37, 'TEXT:Bye']], 30], []), ('normal control', [[[0, 'ENM'], [29, 'TEXT:Bye'], [59, 'TEXT: there']], 25], []), ('normal control', [[[3, 'TEXT: there'], [48, 'TEXT:Hi'], [49, 'TEXT:Bye'], [78, 'TEXT:Hi']], 29], []), ('normal control', [[[3, 'TEXT:Bye'], [18, 'TEXT:Bye'], [25, 'TEXT:Bye'], [40, 'TEXT: there']], 30], [])], [('regression: flip emission guard', [[[30, 'EOC'], [30, 'TEXT:Hi'], [37, 'ENM']], 24], []), ('regression variant: flip emission guard', [[[30, 'TEXT: there'], [30, 'EOC'], [59, 'ENM']], 30], []), ('partial repair probe: flip emission guard', [[[30, 'EOC'], [59, 'EOC'], [60, 'TEXT: there'], [89, 'TEXT: there'], [96, 'ENM'], [96, 'TEXT:Bye'], [96, 'TEXT:Bye'], [96, 'TEXT: there']], 30], []), ('partial repair variant: flip emission guard', [[[30, 'EOC'], [31, 'ENM'], [32, 'EOC']], 29], []), ('normal control', [[[0, 'ENM'], [7, 'TEXT: there'], [37, 'EDM']], 25], []), ('normal control', [[[3, 'ENM'], [10, 'TEXT:Bye']], 25], []), ('normal control', [[[0, 'TEXT: there'], [7, 'TEXT:Hi'], [22, 'TEXT:Bye']], 29], [])], [('regression: flip emission guard', [[[0, 'EOC'], [7, 'TEXT:Bye'], [52, 'EDM'], [59, 'TEXT:Bye'], [74, 'EOC']], 24], []), ('regression variant: flip emission guard', [[[30, 'EDM'], [30, 'EOC'], [60, 'ENM'], [89, 'ENM']], 25], []), ('partial repair probe: flip emission guard', [[[0, 'EOC'], [29, 'EOC'], [29, 'ENM'], [36, 'TEXT: there'], [37, 'TEXT: there'], [38, 'EOC']], 25], []), ('partial repair variant: flip emission guard', [[[0, 'TEXT:Bye'], [7, 'EOC'], [14, 'EDM'], [43, 'ENM'], [88, 'EDM'], [95, 'EOC'], [95, 'EOC'], [125, 'TEXT:Bye']], 24], [[291, 583, 'Bye']]), ('normal control', [[[0, 'TEXT:Bye'], [30, 'TEXT: there'], [37, 'ENM'], [82, 'EDM'], [127, 'TEXT:Hi'], [128, 'TEXT: there'], [158, 'TEXT:Hi'], [187, 'TEXT: there']], 29], []), ('normal control', [[[3, 'TEXT:Bye'], [18, 'ENM']], 24], []), ('normal control', [[[3, 'TEXT: there'], [33, 'TEXT:Bye'], [62, 'EDM']], 29], [])]]\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 any subtitle 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-subtitle-cue-timing-pop-on-caption-buffers-flip-emission-guard","generated_at":"2026-09-29T14:49:33.410639+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Subtitle timing defects shift, hide or overlap captions that viewers depend on for comprehension and accessibility.","root_cause":"EOC emits the displayed memory even when it is empty.","sha256":"10518a3d93059f189f3ca4033fedd66ad28653fad5c462e533b6e5f8e6858cfd","title":"Pop-on caption buffer timing: flip emission guard · 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":40.587,"exit_code":1,"observations":[{"actual":[[1000,2000,"Hi"]],"check":"regression: flip emission guard","expected":[[1000,2000,"Hi"]],"passed":true},{"actual":[[1233,1733,"Bye"]],"check":"regression variant: flip emission guard","expected":[[1233,1733,"Bye"]],"passed":true},{"actual":[[120,1280,""]],"check":"partial repair probe: flip emission guard","expected":[],"passed":false},{"actual":[[1920,1960,"Hi"],[1960,4920,""],[4920,5200,"HiHiBye"]],"check":"partial repair variant: flip emission guard","expected":[[1920,1960,"Hi"],[4920,5200,"HiHiBye"]],"passed":false},{"actual":[],"check":"normal control","expected":[],"passed":true},{"actual":[],"check":"normal control","expected":[],"passed":true},{"actual":[],"check":"normal control","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: flip emission guard\", \"actual\": [[1000, 2000, \"Hi\"]], \"expected\": [[1000, 2000, \"Hi\"]], \"passed\": true}, {\"check\": \"regression variant: flip emission guard\", \"actual\": [[1233, 1733, \"Bye\"]], \"expected\": [[1233, 1733, \"Bye\"]], \"passed\": true}, {\"check\": \"partial repair probe: flip emission guard\", \"actual\": [[120, 1280, \"\"]], \"expected\": [], \"passed\": false}, {\"check\": \"partial repair variant: flip emission guard\", \"actual\": [[1920, 1960, \"Hi\"], [1960, 4920, \"\"], [4920, 5200, \"HiHiBye\"]], \"expected\": [[1920, 1960, \"Hi\"], [4920, 5200, \"HiHiBye\"]], \"passed\": false}, {\"check\": \"normal control\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"normal control\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"normal control\", \"actual\": [], \"expected\": [], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":42.793,"exit_code":1,"observations":[{"actual":[[null,1000,""],[1000,2000,"Hi"]],"check":"regression: flip emission guard","expected":[[1000,2000,"Hi"]],"passed":false},{"actual":[[null,1233,""],[1233,1733,"Bye"]],"check":"regression variant: flip emission guard","expected":[[1233,1733,"Bye"]],"passed":false},{"actual":[[null,120,""],[120,1280,""]],"check":"partial repair probe: flip emission guard","expected":[],"passed":false},{"actual":[[null,1920,""],[1920,1960,"Hi"],[1960,4920,""],[4920,5200,"HiHiBye"]],"check":"partial repair variant: flip emission guard","expected":[[1920,1960,"Hi"],[4920,5200,"HiHiBye"]],"passed":false},{"actual":[],"check":"normal control","expected":[],"passed":true},{"actual":[],"check":"normal control","expected":[],"passed":true},{"actual":[],"check":"normal control","expected":[],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: flip emission guard\", \"actual\": [[null, 1000, \"\"], [1000, 2000, \"Hi\"]], \"expected\": [[1000, 2000, \"Hi\"]], \"passed\": false}, {\"check\": \"regression variant: flip emission guard\", \"actual\": [[null, 1233, \"\"], [1233, 1733, \"Bye\"]], \"expected\": [[1233, 1733, \"Bye\"]], \"passed\": false}, {\"check\": \"partial repair probe: flip emission guard\", \"actual\": [[null, 120, \"\"], [120, 1280, \"\"]], \"expected\": [], \"passed\": false}, {\"check\": \"partial repair variant: flip emission guard\", \"actual\": [[null, 1920, \"\"], [1920, 1960, \"Hi\"], [1960, 4920, \"\"], [4920, 5200, \"HiHiBye\"]], \"expected\": [[1920, 1960, \"Hi\"], [4920, 5200, \"HiHiBye\"]], \"passed\": false}, {\"check\": \"normal control\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"normal control\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"normal control\", \"actual\": [], \"expected\": [], \"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."}}