{"abstract":"A-law input reduction keeps one extra precision bit.","category":"PCM sample encoding","checks":8,"contract":"Stipulated bounded A-law-style PCM encoder with negative complement offset, thirteen-bit working magnitude, segment-specific shifts and alternating wire mask.","contract_signature":"samples","evaluation_group":"s3-pcm-pcm-alaw-code-selection","failed_approach":"Dropping one extra bit halves the companding input range.","family":"s3-pcm-pcm-alaw-code-selection-input-resolution","id":"FA-49871","implementations":{"attempt":{"sha256":"871db97ea98e1d3a0a5e49f3918d78e7e3e6f9bda0d55c15cd1e70165b093fc5","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(samples):\n    out=[]\n    for sample in samples:\n        negative=sample<0\n        magnitude=(-sample-1 if negative else sample)>>4\n        magnitude=min(magnitude,4095)\n        segment=0\n        while segment<7 and magnitude>=(32<<segment):\n            segment+=1\n        shift=1 if segment<2 else segment\n        mantissa=(magnitude>>shift)&15\n        code=(0 if negative else 128)|(segment<<4)|mantissa\n        out.append(code^85)\n    return out\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('oracle 1', solve(*([0, 8, -8, 16, -16],)), [213, 213, 85, 212, 85])\ncheck('oracle 2', solve(*([256, -256, 264, -264],)), [197, 90, 197, 69])\ncheck('oracle 3', solve(*([32767, -32768, 40000, -40000],)), [170, 42, 170, 42])\ncheck('oracle 4', solve(*([],)), [])\ncheck('oracle 5', solve(*([1024, 2048, 8192],)), [229, 149, 181])\ncheck('oracle 6', solve(*([1, -1, 127, -128],)), [213, 85, 210, 82])\ncheck('oracle 7', solve(*([512, -513, 4096, -4097],)), [245, 117, 133, 5])\nif N == 1: check('variant packet 1', solve(*[[0, 8, -8, 16, -16, 0, 8, -8, 16, -16]]), [213, 213, 85, 212, 85, 213, 213, 85, 212, 85])\nif N == 2: check('variant packet 2', solve(*[[0, 8, -8, 16, -16, 0, 8, -8, 16, -16, 0, 8, -8, 16, -16]]), [213, 213, 85, 212, 85, 213, 213, 85, 212, 85, 213, 213, 85, 212, 85])\nif N == 3: check('variant packet 3', solve(*[[0, 8, -8, 16, -16, 0, 8, -8, 16, -16, 0, 8, -8, 16, -16, 0, 8, -8, 16, -16]]), [213, 213, 85, 212, 85, 213, 213, 85, 212, 85, 213, 213, 85, 212, 85, 213, 213, 85, 212, 85])\nif N == 4: check('variant packet 4', solve(*[[0, 8, -8, 16, -16, 0, 8, -8, 16, -16, 0, 8, -8, 16, -16, 0, 8, -8, 16, -16, 0, 8, -8, 16, -16]]), [213, 213, 85, 212, 85, 213, 213, 85, 212, 85, 213, 213, 85, 212, 85, 213, 213, 85, 212, 85, 213, 213, 85, 212, 85])\nif N == 5: check('variant packet 5', solve(*[[0, 8, -8, 16, -16, 0, 8, -8, 16, -16, 0, 8, -8, 16, -16, 0, 8, -8, 16, -16, 0, 8, -8, 16, -16, 0, 8, -8, 16, -16]]), [213, 213, 85, 212, 85, 213, 213, 85, 212, 85, 213, 213, 85, 212, 85, 213, 213, 85, 212, 85, 213, 213, 85, 212, 85, 213, 213, 85, 212, 85])\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":"0971e904459bb72b4df8293bb1e83306623deac9c2e9bc3bf27e20e50020a99b","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(samples):\n    out=[]\n    for sample in samples:\n        negative=sample<0\n        magnitude=(-sample-1 if negative else sample)>>2\n        magnitude=min(magnitude,4095)\n        segment=0\n        while segment<7 and magnitude>=(32<<segment):\n            segment+=1\n        shift=1 if segment<2 else segment\n        mantissa=(magnitude>>shift)&15\n        code=(0 if negative else 128)|(segment<<4)|mantissa\n        out.append(code^85)\n    return out\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('oracle 1', solve(*([0, 8, -8, 16, -16],)), [213, 213, 85, 212, 85])\ncheck('oracle 2', solve(*([256, -256, 264, -264],)), [197, 90, 197, 69])\ncheck('oracle 3', solve(*([32767, -32768, 40000, -40000],)), [170, 42, 170, 42])\ncheck('oracle 4', solve(*([],)), [])\ncheck('oracle 5', solve(*([1024, 2048, 8192],)), [229, 149, 181])\ncheck('oracle 6', solve(*([1, -1, 127, -128],)), [213, 85, 210, 82])\ncheck('oracle 7', solve(*([512, -513, 4096, -4097],)), [245, 117, 133, 5])\nif N == 1: check('variant packet 1', solve(*[[0, 8, -8, 16, -16, 0, 8, -8, 16, -16]]), [213, 213, 85, 212, 85, 213, 213, 85, 212, 85])\nif N == 2: check('variant packet 2', solve(*[[0, 8, -8, 16, -16, 0, 8, -8, 16, -16, 0, 8, -8, 16, -16]]), [213, 213, 85, 212, 85, 213, 213, 85, 212, 85, 213, 213, 85, 212, 85])\nif N == 3: check('variant packet 3', solve(*[[0, 8, -8, 16, -16, 0, 8, -8, 16, -16, 0, 8, -8, 16, -16, 0, 8, -8, 16, -16]]), [213, 213, 85, 212, 85, 213, 213, 85, 212, 85, 213, 213, 85, 212, 85, 213, 213, 85, 212, 85])\nif N == 4: check('variant packet 4', solve(*[[0, 8, -8, 16, -16, 0, 8, -8, 16, -16, 0, 8, -8, 16, -16, 0, 8, -8, 16, -16, 0, 8, -8, 16, -16]]), [213, 213, 85, 212, 85, 213, 213, 85, 212, 85, 213, 213, 85, 212, 85, 213, 213, 85, 212, 85, 213, 213, 85, 212, 85])\nif N == 5: check('variant packet 5', solve(*[[0, 8, -8, 16, -16, 0, 8, -8, 16, -16, 0, 8, -8, 16, -16, 0, 8, -8, 16, -16, 0, 8, -8, 16, -16, 0, 8, -8, 16, -16]]), [213, 213, 85, 212, 85, 213, 213, 85, 212, 85, 213, 213, 85, 212, 85, 213, 213, 85, 212, 85, 213, 213, 85, 212, 85, 213, 213, 85, 212, 85])\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-pcm-alaw-code-selection-input-resolution","generated_at":"2026-09-29T14:45:04.164617+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":"A-law input reduction keeps one extra precision bit.","sha256":"7c4c8ef74108ff62212ed565b3302b08bf63ea61ab562ea46725494e329ba019","title":"Pcm alaw code selection: input resolution · 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":39.66,"exit_code":1,"observations":[{"actual":[213,213,85,213,85],"check":"oracle 1","expected":[213,213,85,212,85],"passed":false},{"actual":[221,82,221,93],"check":"oracle 2","expected":[197,90,197,69],"passed":false},{"actual":[186,58,166,38],"check":"oracle 3","expected":[170,42,170,42],"passed":false},{"actual":[],"check":"oracle 4","expected":[],"passed":true},{"actual":[245,229,133],"check":"oracle 5","expected":[229,149,181],"passed":false},{"actual":[213,85,214,86],"check":"oracle 6","expected":[213,85,210,82],"passed":false},{"actual":[197,69,149,21],"check":"oracle 7","expected":[245,117,133,5],"passed":false},{"actual":[213,213,85,213,85,213,213,85,213,85],"check":"variant packet 1","expected":[213,213,85,212,85,213,213,85,212,85],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"oracle 1\", \"actual\": [213, 213, 85, 213, 85], \"expected\": [213, 213, 85, 212, 85], \"passed\": false}, {\"check\": \"oracle 2\", \"actual\": [221, 82, 221, 93], \"expected\": [197, 90, 197, 69], \"passed\": false}, {\"check\": \"oracle 3\", \"actual\": [186, 58, 166, 38], \"expected\": [170, 42, 170, 42], \"passed\": false}, {\"check\": \"oracle 4\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"oracle 5\", \"actual\": [245, 229, 133], \"expected\": [229, 149, 181], \"passed\": false}, {\"check\": \"oracle 6\", \"actual\": [213, 85, 214, 86], \"expected\": [213, 85, 210, 82], \"passed\": false}, {\"check\": \"oracle 7\", \"actual\": [197, 69, 149, 21], \"expected\": [245, 117, 133, 5], \"passed\": false}, {\"check\": \"variant packet 1\", \"actual\": [213, 213, 85, 213, 85, 213, 213, 85, 213, 85], \"expected\": [213, 213, 85, 212, 85, 213, 213, 85, 212, 85], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":38.186,"exit_code":1,"observations":[{"actual":[213,212,85,215,84],"check":"oracle 1","expected":[213,213,85,212,85],"passed":false},{"actual":[245,74,245,117],"check":"oracle 2","expected":[197,90,197,69],"passed":false},{"actual":[170,42,170,42],"check":"oracle 3","expected":[170,42,170,42],"passed":true},{"actual":[],"check":"oracle 4","expected":[],"passed":true},{"actual":[149,133,165],"check":"oracle 5","expected":[229,149,181],"passed":false},{"actual":[213,85,218,90],"check":"oracle 6","expected":[213,85,210,82],"passed":false},{"actual":[229,101,181,53],"check":"oracle 7","expected":[245,117,133,5],"passed":false},{"actual":[213,212,85,215,84,213,212,85,215,84],"check":"variant packet 1","expected":[213,213,85,212,85,213,213,85,212,85],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"oracle 1\", \"actual\": [213, 212, 85, 215, 84], \"expected\": [213, 213, 85, 212, 85], \"passed\": false}, {\"check\": \"oracle 2\", \"actual\": [245, 74, 245, 117], \"expected\": [197, 90, 197, 69], \"passed\": false}, {\"check\": \"oracle 3\", \"actual\": [170, 42, 170, 42], \"expected\": [170, 42, 170, 42], \"passed\": true}, {\"check\": \"oracle 4\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"oracle 5\", \"actual\": [149, 133, 165], \"expected\": [229, 149, 181], \"passed\": false}, {\"check\": \"oracle 6\", \"actual\": [213, 85, 218, 90], \"expected\": [213, 85, 210, 82], \"passed\": false}, {\"check\": \"oracle 7\", \"actual\": [229, 101, 181, 53], \"expected\": [245, 117, 133, 5], \"passed\": false}, {\"check\": \"variant packet 1\", \"actual\": [213, 212, 85, 215, 84, 213, 212, 85, 215, 84], \"expected\": [213, 213, 85, 212, 85, 213, 213, 85, 212, 85], \"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."}}