{"abstract":"A 24-bit negative sample is decoded without sign extension.","category":"PCM sample encoding","checks":4,"contract":"Decode byte-value list length divisible by three as signed little-endian 24-bit PCM.","evaluation_group":"xaud-signed-twenty-four-sign-extension","failed_approach":"Reading only two bytes truncates the high byte and changes dynamic range.","family":"xaud-signed-twenty-four-sign-extension","id":"FA-10791","implementations":{"attempt":{"sha256":"4814a3a0ba821a345690417b7955212e2625f93730617d74c611791bcb03d512","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(data):\n    return [int.from_bytes(bytes(data[i:i+2]),\"little\",signed=True) for i in range(0,len(data),3)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1',solve(*([0, 0, 128],)),[-8388608])\ncheck('fixture 2',solve(*([255, 255, 127],)),[8388607])\ncheck('fixture 3',solve(*([255, 255, 255],)),[-1])\ncheck('fixture 4',solve(*([1, 0, 0],)),[1])\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":"384ad8c1f8c0561373d0595b79b93c70ae14f090b8a32b321eb759a9642c2d98","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(data):\n    return [int.from_bytes(bytes(data[i:i+3]),\"little\",signed=False) for i in range(0,len(data),3)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1',solve(*([0, 0, 128],)),[-8388608])\ncheck('fixture 2',solve(*([255, 255, 127],)),[8388607])\ncheck('fixture 3',solve(*([255, 255, 255],)),[-1])\ncheck('fixture 4',solve(*([1, 0, 0],)),[1])\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":"c6221f2306339f044484bb9cd2fc0539131c5486758b3c63914cf3e9b6ae5747","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(data):\n    return [int.from_bytes(bytes(data[i:i+3]),\"little\",signed=True) for i in range(0,len(data),3)]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('fixture 1',solve(*([0, 0, 128],)),[-8388608])\ncheck('fixture 2',solve(*([255, 255, 127],)),[8388607])\ncheck('fixture 3',solve(*([255, 255, 255],)),[-1])\ncheck('fixture 4',solve(*([1, 0, 0],)),[1])\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":"xaud-signed-twenty-four-sign-extension","generated_at":"2026-09-29T14:38:42.287972+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"A pure Python local audio pipeline stage with explicit sample formats and frame conventions; no real-time device or signal-spectrum claims.","repair":"Apply the explicit PCM/playback contract: Decode byte-value list length divisible by three as signed little-endian 24-bit PCM.","root_cause":"A 24-bit negative sample is decoded without sign extension.","sha256":"002525d268f80eab246cc8c914ebf1638f2f14a32cf32fc05e379f2c94bb7f7d","title":"Signed twenty four sign extension · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":43.37,"exit_code":1,"observations":[{"actual":[0],"check":"fixture 1","expected":[-8388608],"passed":false},{"actual":[-1],"check":"fixture 2","expected":[8388607],"passed":false},{"actual":[-1],"check":"fixture 3","expected":[-1],"passed":true},{"actual":[1],"check":"fixture 4","expected":[1],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [0], \"expected\": [-8388608], \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": [-1], \"expected\": [8388607], \"passed\": false}, {\"check\": \"fixture 3\", \"actual\": [-1], \"expected\": [-1], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [1], \"expected\": [1], \"passed\": true}], \"passed\": false}\n"},"broken":{"elapsed_ms":44.271,"exit_code":1,"observations":[{"actual":[8388608],"check":"fixture 1","expected":[-8388608],"passed":false},{"actual":[8388607],"check":"fixture 2","expected":[8388607],"passed":true},{"actual":[16777215],"check":"fixture 3","expected":[-1],"passed":false},{"actual":[1],"check":"fixture 4","expected":[1],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [8388608], \"expected\": [-8388608], \"passed\": false}, {\"check\": \"fixture 2\", \"actual\": [8388607], \"expected\": [8388607], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [16777215], \"expected\": [-1], \"passed\": false}, {\"check\": \"fixture 4\", \"actual\": [1], \"expected\": [1], \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":38.741,"exit_code":0,"observations":[{"actual":[-8388608],"check":"fixture 1","expected":[-8388608],"passed":true},{"actual":[8388607],"check":"fixture 2","expected":[8388607],"passed":true},{"actual":[-1],"check":"fixture 3","expected":[-1],"passed":true},{"actual":[1],"check":"fixture 4","expected":[1],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"fixture 1\", \"actual\": [-8388608], \"expected\": [-8388608], \"passed\": true}, {\"check\": \"fixture 2\", \"actual\": [8388607], \"expected\": [8388607], \"passed\": true}, {\"check\": \"fixture 3\", \"actual\": [-1], \"expected\": [-1], \"passed\": true}, {\"check\": \"fixture 4\", \"actual\": [1], \"expected\": [1], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}