{"abstract":"For any buffer after the first, events are given absolute sample positions far beyond the buffer size.","category":"MIDI event timing","checks":8,"contract":"Input [sample_rate, buffer_start_sample, buffer_size, event_times_us]. Each event maps to sample position us*rate/1000000 rounded half up. Positions before the buffer start are \"late\", positions at or after start+size are \"future\", otherwise the offset within the buffer. Invalid rate or size returns None.","contract_signature":"x","evaluation_group":"w2-midi-event-timing-buffer-sample-offset","failed_approach":"Reducing modulo the buffer size only works when buffers start at multiples of their size.","family":"w2-midi-event-timing-buffer-sample-offset-buffer-relative-offset","id":"FA-81836","implementations":{"attempt":{"sha256":"0f18deec2dd52500608fe598e21bc767e8518ff7f1725307e6a8cc9a093bc009","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    if not isinstance(x, list) or len(x) != 4:\n        return None\n    sr, start, size, events = x\n    if sr <= 0 or size <= 0:\n        return None\n    out = []\n    for us in events:\n        pos = (2 * us * sr + 1000000) // 2000000\n        if pos < start:\n            out.append('late')\n        elif pos >= start + size:\n            out.append('future')\n        else:\n            out.append(pos % size)\n    return out\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[([48000, 0, 256, [0, 1000, 5333, 5334]], [0, 48, 'future', 'future']), ([48000, 480, 256, [10000, 10010, 15332, 15333]], [0, 0, 'future', 'future']), ([44100, 441, 128, [10000, 10011, 12902, 12903]], [0, 0, 'future', 'future']), ([48000, 48000, 512, [1000000, 1010667, 1010656, 999990]], [0, 'future', 511, 0]), ([48000, 0, 64, [10, 11, 1333, 1343]], [0, 1, 'future', 'future']), ([48000, 0, 0, [0]], None), ([0, 0, 10, [0]], None), ([1000, 0, 4, [499, 500, 3499, 3500]], [0, 1, 3, 'future'])], [([48000, 480, 256, [10000, 10010, 15332, 15333]], [0, 0, 'future', 'future']), ([44100, 441, 128, [10000, 10011, 12902, 12903]], [0, 0, 'future', 'future']), ([48000, 48000, 512, [1000000, 1010667, 1010656, 999990]], [0, 'future', 511, 0]), ([1000, 10, 5, [9500, 10000, 14499, 14500]], [0, 0, 4, 'future']), ([44100, 1024, 256, [23220, 23232, 29025, 29037]], [0, 1, 'future', 'future']), ([8000, 100, 10, [12500, 12562, 13687, 13688]], [0, 0, 9, 'future']), ([0, 0, 10, [0]], None), ([1000, 0, 4, [499, 500, 3499, 3500]], [0, 1, 3, 'future'])], [([48000, 0, 256, [0, 1000, 5333, 5334]], [0, 48, 'future', 'future']), ([44100, 441, 128, [10000, 10011, 12902, 12903]], [0, 0, 'future', 'future']), ([48000, 48000, 512, [1000000, 1010667, 1010656, 999990]], [0, 'future', 511, 0]), ([1000, 10, 5, [9500, 10000, 14499, 14500]], [0, 0, 4, 'future']), ([48000, 0, 64, [10, 11, 1333, 1343]], [0, 1, 'future', 'future']), ([44100, 1024, 256, [23220, 23232, 29025, 29037]], [0, 1, 'future', 'future']), ([8000, 100, 10, [12500, 12562, 13687, 13688]], [0, 0, 9, 'future']), ([96000, 960, 96, [10000, 10005, 10995, 11000]], [0, 0, 'future', 'future'])], [([48000, 0, 256, [0, 1000, 5333, 5334]], [0, 48, 'future', 'future']), ([48000, 480, 256, [10000, 10010, 15332, 15333]], [0, 0, 'future', 'future']), ([1000, 10, 5, [9500, 10000, 14499, 14500]], [0, 0, 4, 'future']), ([48000, 0, 64, [10, 11, 1333, 1343]], [0, 1, 'future', 'future']), ([44100, 1024, 256, [23220, 23232, 29025, 29037]], [0, 1, 'future', 'future']), ([8000, 100, 10, [12500, 12562, 13687, 13688]], [0, 0, 9, 'future']), ([48000, 0, 0, [0]], None), ([96000, 960, 96, [10000, 10005, 10995, 11000]], [0, 0, 'future', 'future'])], [([48000, 0, 256, [0, 1000, 5333, 5334]], [0, 48, 'future', 'future']), ([44100, 441, 128, [10000, 10011, 12902, 12903]], [0, 0, 'future', 'future']), ([48000, 0, 64, [10, 11, 1333, 1343]], [0, 1, 'future', 'future']), ([44100, 1024, 256, [23220, 23232, 29025, 29037]], [0, 1, 'future', 'future']), ([48000, 0, 0, [0]], None), ([0, 0, 10, [0]], None), ([96000, 960, 96, [10000, 10005, 10995, 11000]], [0, 0, 'future', 'future']), ([1000, 0, 4, [499, 500, 3499, 3500]], [0, 1, 3, 'future'])]]\nfor i, (args, expected) in enumerate(fixtures[N-1]):\n    check(\"oracle %d\" % i, 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":"0d23918d744a51a93009d83f68209f59b7c5aec97844c145cdc4367886ca65ff","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(x):\n    if not isinstance(x, list) or len(x) != 4:\n        return None\n    sr, start, size, events = x\n    if sr <= 0 or size <= 0:\n        return None\n    out = []\n    for us in events:\n        pos = (2 * us * sr + 1000000) // 2000000\n        if pos < start:\n            out.append('late')\n        elif pos >= start + size:\n            out.append('future')\n        else:\n            out.append(pos)\n    return out\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[([48000, 0, 256, [0, 1000, 5333, 5334]], [0, 48, 'future', 'future']), ([48000, 480, 256, [10000, 10010, 15332, 15333]], [0, 0, 'future', 'future']), ([44100, 441, 128, [10000, 10011, 12902, 12903]], [0, 0, 'future', 'future']), ([48000, 48000, 512, [1000000, 1010667, 1010656, 999990]], [0, 'future', 511, 0]), ([48000, 0, 64, [10, 11, 1333, 1343]], [0, 1, 'future', 'future']), ([48000, 0, 0, [0]], None), ([0, 0, 10, [0]], None), ([1000, 0, 4, [499, 500, 3499, 3500]], [0, 1, 3, 'future'])], [([48000, 480, 256, [10000, 10010, 15332, 15333]], [0, 0, 'future', 'future']), ([44100, 441, 128, [10000, 10011, 12902, 12903]], [0, 0, 'future', 'future']), ([48000, 48000, 512, [1000000, 1010667, 1010656, 999990]], [0, 'future', 511, 0]), ([1000, 10, 5, [9500, 10000, 14499, 14500]], [0, 0, 4, 'future']), ([44100, 1024, 256, [23220, 23232, 29025, 29037]], [0, 1, 'future', 'future']), ([8000, 100, 10, [12500, 12562, 13687, 13688]], [0, 0, 9, 'future']), ([0, 0, 10, [0]], None), ([1000, 0, 4, [499, 500, 3499, 3500]], [0, 1, 3, 'future'])], [([48000, 0, 256, [0, 1000, 5333, 5334]], [0, 48, 'future', 'future']), ([44100, 441, 128, [10000, 10011, 12902, 12903]], [0, 0, 'future', 'future']), ([48000, 48000, 512, [1000000, 1010667, 1010656, 999990]], [0, 'future', 511, 0]), ([1000, 10, 5, [9500, 10000, 14499, 14500]], [0, 0, 4, 'future']), ([48000, 0, 64, [10, 11, 1333, 1343]], [0, 1, 'future', 'future']), ([44100, 1024, 256, [23220, 23232, 29025, 29037]], [0, 1, 'future', 'future']), ([8000, 100, 10, [12500, 12562, 13687, 13688]], [0, 0, 9, 'future']), ([96000, 960, 96, [10000, 10005, 10995, 11000]], [0, 0, 'future', 'future'])], [([48000, 0, 256, [0, 1000, 5333, 5334]], [0, 48, 'future', 'future']), ([48000, 480, 256, [10000, 10010, 15332, 15333]], [0, 0, 'future', 'future']), ([1000, 10, 5, [9500, 10000, 14499, 14500]], [0, 0, 4, 'future']), ([48000, 0, 64, [10, 11, 1333, 1343]], [0, 1, 'future', 'future']), ([44100, 1024, 256, [23220, 23232, 29025, 29037]], [0, 1, 'future', 'future']), ([8000, 100, 10, [12500, 12562, 13687, 13688]], [0, 0, 9, 'future']), ([48000, 0, 0, [0]], None), ([96000, 960, 96, [10000, 10005, 10995, 11000]], [0, 0, 'future', 'future'])], [([48000, 0, 256, [0, 1000, 5333, 5334]], [0, 48, 'future', 'future']), ([44100, 441, 128, [10000, 10011, 12902, 12903]], [0, 0, 'future', 'future']), ([48000, 0, 64, [10, 11, 1333, 1343]], [0, 1, 'future', 'future']), ([44100, 1024, 256, [23220, 23232, 29025, 29037]], [0, 1, 'future', 'future']), ([48000, 0, 0, [0]], None), ([0, 0, 10, [0]], None), ([96000, 960, 96, [10000, 10005, 10995, 11000]], [0, 0, 'future', 'future']), ([1000, 0, 4, [499, 500, 3499, 3500]], [0, 1, 3, 'future'])]]\nfor i, (args, expected) in enumerate(fixtures[N-1]):\n    check(\"oracle %d\" % i, 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 is not a complete Standard MIDI File or MIDI 1.0/2.0 implementation. 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-midi-event-timing-buffer-sample-offset-buffer-relative-offset","generated_at":"2026-09-29T14:50:06.638069+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"MIDI sequencers, file readers and synth drivers depend on exact event ordering and tick/time arithmetic.","root_cause":"The offset is not made relative to the buffer start.","sha256":"a091a0a461d6cd218ad8a4544d99211355ad37b4bc777782ec05963bd9ea89d9","title":"Event placement inside an audio render buffer: absolute sample position returned as offset · 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":40.829,"exit_code":1,"observations":[{"actual":[0,48,"future","future"],"check":"oracle 0","expected":[0,48,"future","future"],"passed":true},{"actual":[224,224,"future","future"],"check":"oracle 1","expected":[0,0,"future","future"],"passed":false},{"actual":[57,57,"future","future"],"check":"oracle 2","expected":[0,0,"future","future"],"passed":false},{"actual":[384,"future",383,384],"check":"oracle 3","expected":[0,"future",511,0],"passed":false},{"actual":[0,1,"future","future"],"check":"oracle 4","expected":[0,1,"future","future"],"passed":true},{"actual":null,"check":"oracle 5","expected":null,"passed":true},{"actual":null,"check":"oracle 6","expected":null,"passed":true},{"actual":[0,1,3,"future"],"check":"oracle 7","expected":[0,1,3,"future"],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"oracle 0\", \"actual\": [0, 48, \"future\", \"future\"], \"expected\": [0, 48, \"future\", \"future\"], \"passed\": true}, {\"check\": \"oracle 1\", \"actual\": [224, 224, \"future\", \"future\"], \"expected\": [0, 0, \"future\", \"future\"], \"passed\": false}, {\"check\": \"oracle 2\", \"actual\": [57, 57, \"future\", \"future\"], \"expected\": [0, 0, \"future\", \"future\"], \"passed\": false}, {\"check\": \"oracle 3\", \"actual\": [384, \"future\", 383, 384], \"expected\": [0, \"future\", 511, 0], \"passed\": false}, {\"check\": \"oracle 4\", \"actual\": [0, 1, \"future\", \"future\"], \"expected\": [0, 1, \"future\", \"future\"], \"passed\": true}, {\"check\": \"oracle 5\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"oracle 6\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"oracle 7\", \"actual\": [0, 1, 3, \"future\"], \"expected\": [0, 1, 3, \"future\"], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":40.406,"exit_code":1,"observations":[{"actual":[0,48,"future","future"],"check":"oracle 0","expected":[0,48,"future","future"],"passed":true},{"actual":[480,480,"future","future"],"check":"oracle 1","expected":[0,0,"future","future"],"passed":false},{"actual":[441,441,"future","future"],"check":"oracle 2","expected":[0,0,"future","future"],"passed":false},{"actual":[48000,"future",48511,48000],"check":"oracle 3","expected":[0,"future",511,0],"passed":false},{"actual":[0,1,"future","future"],"check":"oracle 4","expected":[0,1,"future","future"],"passed":true},{"actual":null,"check":"oracle 5","expected":null,"passed":true},{"actual":null,"check":"oracle 6","expected":null,"passed":true},{"actual":[0,1,3,"future"],"check":"oracle 7","expected":[0,1,3,"future"],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"oracle 0\", \"actual\": [0, 48, \"future\", \"future\"], \"expected\": [0, 48, \"future\", \"future\"], \"passed\": true}, {\"check\": \"oracle 1\", \"actual\": [480, 480, \"future\", \"future\"], \"expected\": [0, 0, \"future\", \"future\"], \"passed\": false}, {\"check\": \"oracle 2\", \"actual\": [441, 441, \"future\", \"future\"], \"expected\": [0, 0, \"future\", \"future\"], \"passed\": false}, {\"check\": \"oracle 3\", \"actual\": [48000, \"future\", 48511, 48000], \"expected\": [0, \"future\", 511, 0], \"passed\": false}, {\"check\": \"oracle 4\", \"actual\": [0, 1, \"future\", \"future\"], \"expected\": [0, 1, \"future\", \"future\"], \"passed\": true}, {\"check\": \"oracle 5\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"oracle 6\", \"actual\": null, \"expected\": null, \"passed\": true}, {\"check\": \"oracle 7\", \"actual\": [0, 1, 3, \"future\"], \"expected\": [0, 1, 3, \"future\"], \"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."}}