{"abstract":"Ignoring presentation-time offset misaligns a segment timeline.","category":"Media timeline seeking","checks":4,"contract":"Convert integer media ticks to presentation seconds by subtracting the presentation offset in the same tick units before dividing by positive timescale.","evaluation_group":"xmed-presentation-time-offset-subtracted","failed_approach":"Subtracting tick-valued offset from seconds mixes incompatible units.","family":"xmed-presentation-time-offset-subtracted","id":"FA-11226","implementations":{"attempt":{"sha256":"8c37f3478ad27fd24cb291f406af87b86983e784c9d88a3627c3f0683e84809e","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(ticks, timescale, offset_ticks):\n    return ticks/timescale-offset_ticks\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1',solve(*(1500, 1000, 500)),1)\ncheck('fixture 2',solve(*(90000, 90000, 45000)),0.5)\ncheck('fixture 3',solve(*(0, 1, 0)),0)\ncheck('fixture 4',solve(*(250, 1000, 500)),-0.25)\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":"316408e0d058a1a0d1a460981a6511f8e589fdd71f14c47adce923acaa088959","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(ticks, timescale, offset_ticks):\n    return ticks/timescale\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1',solve(*(1500, 1000, 500)),1)\ncheck('fixture 2',solve(*(90000, 90000, 45000)),0.5)\ncheck('fixture 3',solve(*(0, 1, 0)),0)\ncheck('fixture 4',solve(*(250, 1000, 500)),-0.25)\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":"2e320d66d544377921eafe4a935df9c72e48de7c126c39c41f34768a3cb0e911","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(ticks, timescale, offset_ticks):\n    return (ticks-offset_ticks)/timescale\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1',solve(*(1500, 1000, 500)),1)\ncheck('fixture 2',solve(*(90000, 90000, 45000)),0.5)\ncheck('fixture 3',solve(*(0, 1, 0)),0)\ncheck('fixture 4',solve(*(250, 1000, 500)),-0.25)\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":" 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":"xmed-presentation-time-offset-subtracted","generated_at":"2026-09-29T14:38:46.135222+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A deterministic local media controller stage; metadata and downloaded data are supplied explicitly. No external player, service or codec is required.","repair":"Preserve the media contract: Convert integer media ticks to presentation seconds by subtracting the presentation offset in the same tick units before dividing by positive timescale.","root_cause":"Ignoring presentation-time offset misaligns a segment timeline.","sha256":"a387bf32294e84475a572725d9306792cd204d3edbbe2a10d377ee09b31e911c","title":"Presentation time offset subtracted · case 01","variant":1,"variant_policy":"The five numbered cases rerun the same authored boundary fixtures; they are reproducibility runs, not independent input variants.","verification":{"attempt":{"elapsed_ms":39.367,"exit_code":1,"observations":[{"actual":-498.5,"check":"fixture 1","expected":1,"passed":false},{"actual":-44999.0,"check":"fixture 2","expected":0.5,"passed":false},{"actual":0.0,"check":"fixture 3","expected":0,"passed":true},{"actual":-499.75,"check":"fixture 4","expected":-0.25,"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": -498.5, \"expected\": 1, \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": -44999.0, \"expected\": 0.5, \"passed\": false}, {\"check\": \"fixture 3\", \"actual\": 0.0, \"expected\": 0, \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": -499.75, \"expected\": -0.25, \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":40.193,"exit_code":1,"observations":[{"actual":1.5,"check":"fixture 1","expected":1,"passed":false},{"actual":1.0,"check":"fixture 2","expected":0.5,"passed":false},{"actual":0.0,"check":"fixture 3","expected":0,"passed":true},{"actual":0.25,"check":"fixture 4","expected":-0.25,"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": 1.5, \"expected\": 1, \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": 1.0, \"expected\": 0.5, \"passed\": false}, {\"check\": \"fixture 3\", \"actual\": 0.0, \"expected\": 0, \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": 0.25, \"expected\": -0.25, \"passed\": false}], \"passed\": false}\n"},"fixed":{"elapsed_ms":40.387,"exit_code":0,"observations":[{"actual":1.0,"check":"fixture 1","expected":1,"passed":true},{"actual":0.5,"check":"fixture 2","expected":0.5,"passed":true},{"actual":0.0,"check":"fixture 3","expected":0,"passed":true},{"actual":-0.25,"check":"fixture 4","expected":-0.25,"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": 1.0, \"expected\": 1, \"passed\": true}, {\"check\": \"fixture 2\", \"actual\": 0.5, \"expected\": 0.5, \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": 0.0, \"expected\": 0, \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": -0.25, \"expected\": -0.25, \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}