{"abstract":"Local track timestamps are mixed with the shared presentation timeline.","category":"Media timeline seeking","checks":4,"contract":"Map track-local timestamps to the shared presentation timeline by adding one signed track offset.","evaluation_group":"xmed-track-timestamp-offset-applied-once","failed_approach":"Applying the offset in both demux and presentation stages shifts the track twice.","family":"xmed-track-timestamp-offset-applied-once","id":"FA-11221","implementations":{"attempt":{"sha256":"902da9f57d4d2bf6af761f47345732ad608f33d2a846afeef1932f8eda9e5924","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(timestamps, offset):\n    return [t+2*offset for t in timestamps]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1',solve(*([0, 2], 5)),[5, 7])\ncheck('fixture 2',solve(*([5, 7], -5)),[0, 2])\ncheck('fixture 3',solve(*([], 3)),[])\ncheck('fixture 4',solve(*([0], 0)),[0])\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":"e616a2e6ba861e77285d2178114d5fda3b65207e50d07429805fa834423d58a7","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(timestamps, offset):\n    return list(timestamps)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1',solve(*([0, 2], 5)),[5, 7])\ncheck('fixture 2',solve(*([5, 7], -5)),[0, 2])\ncheck('fixture 3',solve(*([], 3)),[])\ncheck('fixture 4',solve(*([0], 0)),[0])\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":"e917d6414c577be18905b7e09a65b690327793f28fc6be85d6aade92d183ce59","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(timestamps, offset):\n    return [t+offset for t in timestamps]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1',solve(*([0, 2], 5)),[5, 7])\ncheck('fixture 2',solve(*([5, 7], -5)),[0, 2])\ncheck('fixture 3',solve(*([], 3)),[])\ncheck('fixture 4',solve(*([0], 0)),[0])\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-track-timestamp-offset-applied-once","generated_at":"2026-09-29T14:38:46.055626+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: Map track-local timestamps to the shared presentation timeline by adding one signed track offset.","root_cause":"Local track timestamps are mixed with the shared presentation timeline.","sha256":"8e48669da303a334c8775f0d6449a71aef77838980b3a4439fa9b806a7af4dce","title":"Track timestamp offset applied once · 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":39.918,"exit_code":1,"observations":[{"actual":[10,12],"check":"fixture 1","expected":[5,7],"passed":false},{"actual":[-5,-3],"check":"fixture 2","expected":[0,2],"passed":false},{"actual":[],"check":"fixture 3","expected":[],"passed":true},{"actual":[0],"check":"fixture 4","expected":[0],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [10, 12], \"expected\": [5, 7], \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": [-5, -3], \"expected\": [0, 2], \"passed\": false}, {\"check\": \"fixture 3\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [0], \"expected\": [0], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":37.541,"exit_code":1,"observations":[{"actual":[0,2],"check":"fixture 1","expected":[5,7],"passed":false},{"actual":[5,7],"check":"fixture 2","expected":[0,2],"passed":false},{"actual":[],"check":"fixture 3","expected":[],"passed":true},{"actual":[0],"check":"fixture 4","expected":[0],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [0, 2], \"expected\": [5, 7], \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": [5, 7], \"expected\": [0, 2], \"passed\": false}, {\"check\": \"fixture 3\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [0], \"expected\": [0], \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":41.768,"exit_code":0,"observations":[{"actual":[5,7],"check":"fixture 1","expected":[5,7],"passed":true},{"actual":[0,2],"check":"fixture 2","expected":[0,2],"passed":true},{"actual":[],"check":"fixture 3","expected":[],"passed":true},{"actual":[0],"check":"fixture 4","expected":[0],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [5, 7], \"expected\": [5, 7], \"passed\": true}, {\"check\": \"fixture 2\", \"actual\": [0, 2], \"expected\": [0, 2], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [0], \"expected\": [0], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}