{"abstract":"Reconstructed mu-law amplitude retains its encoding bias.","category":"PCM sample encoding","checks":8,"contract":"Decode eight-bit mu-law codewords using complement, three-bit segment, four-bit mantissa and reconstruction bias132; return signed integer PCM amplitudes.","contract_signature":"codes","evaluation_group":"s3-pcm-mulaw-expansion","failed_approach":"Removing the segment-scaled rather than fixed bias destroys segment offsets.","family":"s3-pcm-mulaw-expansion-bias-removal","id":"FA-48981","implementations":{"attempt":{"sha256":"53c73fc4008404db1c33b4c8610f55b80952367c447e72d624665e2911b3029c","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(codes):\n    out=[]\n    for raw in codes:\n        code=(~raw)&255\n        mantissa=code&15\n        exponent=(code>>4)&7\n        amplitude=((mantissa<<3)+132)<<exponent\n        amplitude-=132<<exponent\n        out.append(-amplitude if code&128 else amplitude)\n    return out\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('oracle 1', solve(*([255, 127, 0, 128],)), [0, 0, -32124, 32124])\ncheck('oracle 2', solve(*([254, 253, 252],)), [8, 16, 24])\ncheck('oracle 3', solve(*([240, 239, 224],)), [120, 132, 372])\ncheck('oracle 4', solve(*([16, 32, 64],)), [-15996, -7932, -1884])\ncheck('oracle 5', solve(*([],)), [])\ncheck('oracle 6', solve(*([175, 191, 207, 223],)), [4092, 1980, 924, 396])\ncheck('oracle 7', solve(*([1, 2, 126],)), [-31100, -30076, -8])\nif N == 1: check('variant packet 1', solve(*[[255, 127, 0, 128, 255, 127, 0, 128]]), [0, 0, -32124, 32124, 0, 0, -32124, 32124])\nif N == 2: check('variant packet 2', solve(*[[255, 127, 0, 128, 255, 127, 0, 128, 255, 127, 0, 128]]), [0, 0, -32124, 32124, 0, 0, -32124, 32124, 0, 0, -32124, 32124])\nif N == 3: check('variant packet 3', solve(*[[255, 127, 0, 128, 255, 127, 0, 128, 255, 127, 0, 128, 255, 127, 0, 128]]), [0, 0, -32124, 32124, 0, 0, -32124, 32124, 0, 0, -32124, 32124, 0, 0, -32124, 32124])\nif N == 4: check('variant packet 4', solve(*[[255, 127, 0, 128, 255, 127, 0, 128, 255, 127, 0, 128, 255, 127, 0, 128, 255, 127, 0, 128]]), [0, 0, -32124, 32124, 0, 0, -32124, 32124, 0, 0, -32124, 32124, 0, 0, -32124, 32124, 0, 0, -32124, 32124])\nif N == 5: check('variant packet 5', solve(*[[255, 127, 0, 128, 255, 127, 0, 128, 255, 127, 0, 128, 255, 127, 0, 128, 255, 127, 0, 128, 255, 127, 0, 128]]), [0, 0, -32124, 32124, 0, 0, -32124, 32124, 0, 0, -32124, 32124, 0, 0, -32124, 32124, 0, 0, -32124, 32124, 0, 0, -32124, 32124])\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":"02a6ff333187c1e39c64b7dc3fea70ca5860d60e09f066a195afb301a8cd36d8","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(codes):\n    out=[]\n    for raw in codes:\n        code=(~raw)&255\n        mantissa=code&15\n        exponent=(code>>4)&7\n        amplitude=((mantissa<<3)+132)<<exponent\n        amplitude-=0\n        out.append(-amplitude if code&128 else amplitude)\n    return out\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('oracle 1', solve(*([255, 127, 0, 128],)), [0, 0, -32124, 32124])\ncheck('oracle 2', solve(*([254, 253, 252],)), [8, 16, 24])\ncheck('oracle 3', solve(*([240, 239, 224],)), [120, 132, 372])\ncheck('oracle 4', solve(*([16, 32, 64],)), [-15996, -7932, -1884])\ncheck('oracle 5', solve(*([],)), [])\ncheck('oracle 6', solve(*([175, 191, 207, 223],)), [4092, 1980, 924, 396])\ncheck('oracle 7', solve(*([1, 2, 126],)), [-31100, -30076, -8])\nif N == 1: check('variant packet 1', solve(*[[255, 127, 0, 128, 255, 127, 0, 128]]), [0, 0, -32124, 32124, 0, 0, -32124, 32124])\nif N == 2: check('variant packet 2', solve(*[[255, 127, 0, 128, 255, 127, 0, 128, 255, 127, 0, 128]]), [0, 0, -32124, 32124, 0, 0, -32124, 32124, 0, 0, -32124, 32124])\nif N == 3: check('variant packet 3', solve(*[[255, 127, 0, 128, 255, 127, 0, 128, 255, 127, 0, 128, 255, 127, 0, 128]]), [0, 0, -32124, 32124, 0, 0, -32124, 32124, 0, 0, -32124, 32124, 0, 0, -32124, 32124])\nif N == 4: check('variant packet 4', solve(*[[255, 127, 0, 128, 255, 127, 0, 128, 255, 127, 0, 128, 255, 127, 0, 128, 255, 127, 0, 128]]), [0, 0, -32124, 32124, 0, 0, -32124, 32124, 0, 0, -32124, 32124, 0, 0, -32124, 32124, 0, 0, -32124, 32124])\nif N == 5: check('variant packet 5', solve(*[[255, 127, 0, 128, 255, 127, 0, 128, 255, 127, 0, 128, 255, 127, 0, 128, 255, 127, 0, 128, 255, 127, 0, 128]]), [0, 0, -32124, 32124, 0, 0, -32124, 32124, 0, 0, -32124, 32124, 0, 0, -32124, 32124, 0, 0, -32124, 32124, 0, 0, -32124, 32124])\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":"Stipulated finite model; no claim of hardware timing or full file-format conformance. 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":"s3-pcm-mulaw-expansion-bias-removal","generated_at":"2026-09-29T14:44:55.696318+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Offline PCM interchange uses these exact bounded packet and sample representation decisions.","root_cause":"Reconstructed mu-law amplitude retains its encoding bias.","sha256":"62641af6a757248918bede4c6ba16333a6c27789e9a01d62a929c29dee317488","title":"Mulaw expansion: bias removal · 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":39.14,"exit_code":1,"observations":[{"actual":[0,0,-15360,15360],"check":"oracle 1","expected":[0,0,-32124,32124],"passed":false},{"actual":[8,16,24],"check":"oracle 2","expected":[8,16,24],"passed":true},{"actual":[120,0,240],"check":"oracle 3","expected":[120,132,372],"passed":false},{"actual":[-7680,-3840,-960],"check":"oracle 4","expected":[-15996,-7932,-1884],"passed":false},{"actual":[],"check":"oracle 5","expected":[],"passed":true},{"actual":[0,0,0,0],"check":"oracle 6","expected":[4092,1980,924,396],"passed":false},{"actual":[-14336,-13312,-8],"check":"oracle 7","expected":[-31100,-30076,-8],"passed":false},{"actual":[0,0,-15360,15360,0,0,-15360,15360],"check":"variant packet 1","expected":[0,0,-32124,32124,0,0,-32124,32124],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"oracle 1\", \"actual\": [0, 0, -15360, 15360], \"expected\": [0, 0, -32124, 32124], \"passed\": false}, {\"check\": \"oracle 2\", \"actual\": [8, 16, 24], \"expected\": [8, 16, 24], \"passed\": true}, {\"check\": \"oracle 3\", \"actual\": [120, 0, 240], \"expected\": [120, 132, 372], \"passed\": false}, {\"check\": \"oracle 4\", \"actual\": [-7680, -3840, -960], \"expected\": [-15996, -7932, -1884], \"passed\": false}, {\"check\": \"oracle 5\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"oracle 6\", \"actual\": [0, 0, 0, 0], \"expected\": [4092, 1980, 924, 396], \"passed\": false}, {\"check\": \"oracle 7\", \"actual\": [-14336, -13312, -8], \"expected\": [-31100, -30076, -8], \"passed\": false}, {\"check\": \"variant packet 1\", \"actual\": [0, 0, -15360, 15360, 0, 0, -15360, 15360], \"expected\": [0, 0, -32124, 32124, 0, 0, -32124, 32124], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":38.142,"exit_code":1,"observations":[{"actual":[132,-132,-32256,32256],"check":"oracle 1","expected":[0,0,-32124,32124],"passed":false},{"actual":[140,148,156],"check":"oracle 2","expected":[8,16,24],"passed":false},{"actual":[252,264,504],"check":"oracle 3","expected":[120,132,372],"passed":false},{"actual":[-16128,-8064,-2016],"check":"oracle 4","expected":[-15996,-7932,-1884],"passed":false},{"actual":[],"check":"oracle 5","expected":[],"passed":true},{"actual":[4224,2112,1056,528],"check":"oracle 6","expected":[4092,1980,924,396],"passed":false},{"actual":[-31232,-30208,-140],"check":"oracle 7","expected":[-31100,-30076,-8],"passed":false},{"actual":[132,-132,-32256,32256,132,-132,-32256,32256],"check":"variant packet 1","expected":[0,0,-32124,32124,0,0,-32124,32124],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"oracle 1\", \"actual\": [132, -132, -32256, 32256], \"expected\": [0, 0, -32124, 32124], \"passed\": false}, {\"check\": \"oracle 2\", \"actual\": [140, 148, 156], \"expected\": [8, 16, 24], \"passed\": false}, {\"check\": \"oracle 3\", \"actual\": [252, 264, 504], \"expected\": [120, 132, 372], \"passed\": false}, {\"check\": \"oracle 4\", \"actual\": [-16128, -8064, -2016], \"expected\": [-15996, -7932, -1884], \"passed\": false}, {\"check\": \"oracle 5\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"oracle 6\", \"actual\": [4224, 2112, 1056, 528], \"expected\": [4092, 1980, 924, 396], \"passed\": false}, {\"check\": \"oracle 7\", \"actual\": [-31232, -30208, -140], \"expected\": [-31100, -30076, -8], \"passed\": false}, {\"check\": \"variant packet 1\", \"actual\": [132, -132, -32256, 32256, 132, -132, -32256, 32256], \"expected\": [0, 0, -32124, 32124, 0, 0, -32124, 32124], \"passed\": false}], \"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."}}