{"abstract":"An exact companding segment boundary stays in the lower segment.","category":"PCM sample encoding","checks":8,"contract":"Bounded mu-law-style selection model: clamp magnitude32635, add bias132, select segment and mantissa then complement the full eight-bit code.","evaluation_group":"s3-pcm-pcm-mulaw-code-selection","failed_approach":"Starting at half the threshold advances every segment too early.","family":"s3-pcm-pcm-mulaw-code-selection-segment-boundary","id":"FA-49846","implementations":{"attempt":{"sha256":"004620e991cf416a56f376766f70ebd6987276061c694e6fa315ba01436a1deb","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        amplitude=min(32635,abs(sample))+132\n        exponent=0\n        while exponent<7 and amplitude>=(128<<exponent):\n            exponent+=1\n        mantissa=(amplitude>>(exponent+3))&15\n        code=(128 if negative else 0)|(exponent<<4)|mantissa\n        out.append((~code)&255)\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, 1, -1, 100, -100],)), [255, 255, 127, 242, 114])\ncheck('oracle 2', solve(*([124, 125, -124],)), [239, 239, 111])\ncheck('oracle 3', solve(*([32635, 40000, -40000],)), [128, 128, 0])\ncheck('oracle 4', solve(*([],)), [])\ncheck('oracle 5', solve(*([1000, 4000, 16000],)), [206, 175, 144])\ncheck('oracle 6', solve(*([380, 892, 1916],)), [223, 207, 191])\ncheck('oracle 7', solve(*([-1000, -4000, -16000],)), [78, 47, 16])\nif N == 1: check('variant packet 1', solve(*[[0, 1, -1, 100, -100, 0, 1, -1, 100, -100]]), [255, 255, 127, 242, 114, 255, 255, 127, 242, 114])\nif N == 2: check('variant packet 2', solve(*[[0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100]]), [255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114])\nif N == 3: check('variant packet 3', solve(*[[0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100]]), [255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114])\nif N == 4: check('variant packet 4', solve(*[[0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100]]), [255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114])\nif N == 5: check('variant packet 5', solve(*[[0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100]]), [255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114])\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":"67a71579de58a826c701213669f2aba7aacc18adb75be67e3beb8ed24a21466d","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        amplitude=min(32635,abs(sample))+132\n        exponent=0\n        while exponent<7 and amplitude>(256<<exponent):\n            exponent+=1\n        mantissa=(amplitude>>(exponent+3))&15\n        code=(128 if negative else 0)|(exponent<<4)|mantissa\n        out.append((~code)&255)\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, 1, -1, 100, -100],)), [255, 255, 127, 242, 114])\ncheck('oracle 2', solve(*([124, 125, -124],)), [239, 239, 111])\ncheck('oracle 3', solve(*([32635, 40000, -40000],)), [128, 128, 0])\ncheck('oracle 4', solve(*([],)), [])\ncheck('oracle 5', solve(*([1000, 4000, 16000],)), [206, 175, 144])\ncheck('oracle 6', solve(*([380, 892, 1916],)), [223, 207, 191])\ncheck('oracle 7', solve(*([-1000, -4000, -16000],)), [78, 47, 16])\nif N == 1: check('variant packet 1', solve(*[[0, 1, -1, 100, -100, 0, 1, -1, 100, -100]]), [255, 255, 127, 242, 114, 255, 255, 127, 242, 114])\nif N == 2: check('variant packet 2', solve(*[[0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100]]), [255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114])\nif N == 3: check('variant packet 3', solve(*[[0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100]]), [255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114])\nif N == 4: check('variant packet 4', solve(*[[0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100]]), [255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114])\nif N == 5: check('variant packet 5', solve(*[[0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100]]), [255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114])\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":"9a61544a71b8062ad93686f3ed544e53c854273e6558ea0c346d7822c4809892","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        amplitude=min(32635,abs(sample))+132\n        exponent=0\n        while exponent<7 and amplitude>=(256<<exponent):\n            exponent+=1\n        mantissa=(amplitude>>(exponent+3))&15\n        code=(128 if negative else 0)|(exponent<<4)|mantissa\n        out.append((~code)&255)\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, 1, -1, 100, -100],)), [255, 255, 127, 242, 114])\ncheck('oracle 2', solve(*([124, 125, -124],)), [239, 239, 111])\ncheck('oracle 3', solve(*([32635, 40000, -40000],)), [128, 128, 0])\ncheck('oracle 4', solve(*([],)), [])\ncheck('oracle 5', solve(*([1000, 4000, 16000],)), [206, 175, 144])\ncheck('oracle 6', solve(*([380, 892, 1916],)), [223, 207, 191])\ncheck('oracle 7', solve(*([-1000, -4000, -16000],)), [78, 47, 16])\nif N == 1: check('variant packet 1', solve(*[[0, 1, -1, 100, -100, 0, 1, -1, 100, -100]]), [255, 255, 127, 242, 114, 255, 255, 127, 242, 114])\nif N == 2: check('variant packet 2', solve(*[[0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100]]), [255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114])\nif N == 3: check('variant packet 3', solve(*[[0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100]]), [255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114])\nif N == 4: check('variant packet 4', solve(*[[0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100]]), [255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114])\nif N == 5: check('variant packet 5', solve(*[[0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100, 0, 1, -1, 100, -100]]), [255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114, 255, 255, 127, 242, 114])\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-mulaw-code-selection-segment-boundary","generated_at":"2026-09-29T14:45:03.751685+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.","repair":"Use the stated conversion contract at segment boundary.","root_cause":"An exact companding segment boundary stays in the lower segment.","sha256":"6d586ff395e39c90ff66c814cd5a8dc703386dbf4cdf84e77c27d9b7f361c25f","title":"Pcm mulaw code selection: segment boundary · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":41.25,"exit_code":1,"observations":[{"actual":[231,231,103,225,97],"check":"oracle 1","expected":[255,255,127,242,114],"passed":false},{"actual":[215,215,87],"check":"oracle 2","expected":[239,239,111],"passed":false},{"actual":[128,128,0],"check":"oracle 3","expected":[128,128,0],"passed":true},{"actual":[],"check":"oracle 4","expected":[],"passed":true},{"actual":[183,151,128],"check":"oracle 5","expected":[206,175,144],"passed":false},{"actual":[199,183,167],"check":"oracle 6","expected":[223,207,191],"passed":false},{"actual":[55,23,0],"check":"oracle 7","expected":[78,47,16],"passed":false},{"actual":[231,231,103,225,97,231,231,103,225,97],"check":"variant packet 1","expected":[255,255,127,242,114,255,255,127,242,114],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"oracle 1\", \"actual\": [231, 231, 103, 225, 97], \"expected\": [255, 255, 127, 242, 114], \"passed\": false}, {\"check\": \"oracle 2\", \"actual\": [215, 215, 87], \"expected\": [239, 239, 111], \"passed\": false}, {\"check\": \"oracle 3\", \"actual\": [128, 128, 0], \"expected\": [128, 128, 0], \"passed\": true}, {\"check\": \"oracle 4\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"oracle 5\", \"actual\": [183, 151, 128], \"expected\": [206, 175, 144], \"passed\": false}, {\"check\": \"oracle 6\", \"actual\": [199, 183, 167], \"expected\": [223, 207, 191], \"passed\": false}, {\"check\": \"oracle 7\", \"actual\": [55, 23, 0], \"expected\": [78, 47, 16], \"passed\": false}, {\"check\": \"variant packet 1\", \"actual\": [231, 231, 103, 225, 97, 231, 231, 103, 225, 97], \"expected\": [255, 255, 127, 242, 114, 255, 255, 127, 242, 114], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":39.359,"exit_code":1,"observations":[{"actual":[255,255,127,242,114],"check":"oracle 1","expected":[255,255,127,242,114],"passed":true},{"actual":[255,239,127],"check":"oracle 2","expected":[239,239,111],"passed":false},{"actual":[128,128,0],"check":"oracle 3","expected":[128,128,0],"passed":true},{"actual":[],"check":"oracle 4","expected":[],"passed":true},{"actual":[206,175,144],"check":"oracle 5","expected":[206,175,144],"passed":true},{"actual":[239,223,207],"check":"oracle 6","expected":[223,207,191],"passed":false},{"actual":[78,47,16],"check":"oracle 7","expected":[78,47,16],"passed":true},{"actual":[255,255,127,242,114,255,255,127,242,114],"check":"variant packet 1","expected":[255,255,127,242,114,255,255,127,242,114],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"oracle 1\", \"actual\": [255, 255, 127, 242, 114], \"expected\": [255, 255, 127, 242, 114], \"passed\": true}, {\"check\": \"oracle 2\", \"actual\": [255, 239, 127], \"expected\": [239, 239, 111], \"passed\": false}, {\"check\": \"oracle 3\", \"actual\": [128, 128, 0], \"expected\": [128, 128, 0], \"passed\": true}, {\"check\": \"oracle 4\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"oracle 5\", \"actual\": [206, 175, 144], \"expected\": [206, 175, 144], \"passed\": true}, {\"check\": \"oracle 6\", \"actual\": [239, 223, 207], \"expected\": [223, 207, 191], \"passed\": false}, {\"check\": \"oracle 7\", \"actual\": [78, 47, 16], \"expected\": [78, 47, 16], \"passed\": true}, {\"check\": \"variant packet 1\", \"actual\": [255, 255, 127, 242, 114, 255, 255, 127, 242, 114], \"expected\": [255, 255, 127, 242, 114, 255, 255, 127, 242, 114], \"passed\": true}], \"passed\": false}\n"},"fixed":{"elapsed_ms":40.454,"exit_code":0,"observations":[{"actual":[255,255,127,242,114],"check":"oracle 1","expected":[255,255,127,242,114],"passed":true},{"actual":[239,239,111],"check":"oracle 2","expected":[239,239,111],"passed":true},{"actual":[128,128,0],"check":"oracle 3","expected":[128,128,0],"passed":true},{"actual":[],"check":"oracle 4","expected":[],"passed":true},{"actual":[206,175,144],"check":"oracle 5","expected":[206,175,144],"passed":true},{"actual":[223,207,191],"check":"oracle 6","expected":[223,207,191],"passed":true},{"actual":[78,47,16],"check":"oracle 7","expected":[78,47,16],"passed":true},{"actual":[255,255,127,242,114,255,255,127,242,114],"check":"variant packet 1","expected":[255,255,127,242,114,255,255,127,242,114],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"oracle 1\", \"actual\": [255, 255, 127, 242, 114], \"expected\": [255, 255, 127, 242, 114], \"passed\": true}, {\"check\": \"oracle 2\", \"actual\": [239, 239, 111], \"expected\": [239, 239, 111], \"passed\": true}, {\"check\": \"oracle 3\", \"actual\": [128, 128, 0], \"expected\": [128, 128, 0], \"passed\": true}, {\"check\": \"oracle 4\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"oracle 5\", \"actual\": [206, 175, 144], \"expected\": [206, 175, 144], \"passed\": true}, {\"check\": \"oracle 6\", \"actual\": [223, 207, 191], \"expected\": [223, 207, 191], \"passed\": true}, {\"check\": \"oracle 7\", \"actual\": [78, 47, 16], \"expected\": [78, 47, 16], \"passed\": true}, {\"check\": \"variant packet 1\", \"actual\": [255, 255, 127, 242, 114, 255, 255, 127, 242, 114], \"expected\": [255, 255, 127, 242, 114, 255, 255, 127, 242, 114], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}