{"abstract":"Truncation toward zero differs from floor on negative odd side codes.","category":"PCM sample encoding","checks":8,"contract":"Encode stereo integer PCM through reversible floor lifting: side=L-R, mid=R+floor(side/2), with an explicit odd-side parity sideband.","contract_signature":"pairs","evaluation_group":"s3-pcm-pcm-mid-side-lifting","failed_approach":"Ceiling differs on positive odd side codes.","family":"s3-pcm-pcm-mid-side-lifting-lifting-rounding","id":"FA-49271","implementations":{"attempt":{"sha256":"3005bd5e32d1e2416c4e898788b52b4f961003da0fde2bb3bd740a19b7cb67fe","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(pairs):\n    out=[]\n    for left,right in pairs:\n        side=left-right\n        half=(side+1)//2\n        mid=right+half\n        parity=side&1\n        out.append([mid,side,parity])\n    return out\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('oracle 1', solve(*([[5, 2], [2, 5]],)), [[3, 3, 1], [3, -3, 1]])\ncheck('oracle 2', solve(*([[0, 0], [1, 1]],)), [[0, 0, 0], [1, 0, 0]])\ncheck('oracle 3', solve(*([[-3, 2], [4, -1]],)), [[-1, -5, 1], [1, 5, 1]])\ncheck('oracle 4', solve(*([],)), [])\ncheck('oracle 5', solve(*([[1, 0], [0, 1]],)), [[0, 1, 1], [0, -1, 1]])\ncheck('oracle 6', solve(*([[7, 7], [-7, -7]],)), [[7, 0, 0], [-7, 0, 0]])\ncheck('oracle 7', solve(*([[3, 1], [-3, -1]],)), [[2, 2, 0], [-2, -2, 0]])\nif N == 1: check('variant packet 1', solve(*[[[5, 2], [2, 5], [5, 2], [2, 5]]]), [[3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1]])\nif N == 2: check('variant packet 2', solve(*[[[5, 2], [2, 5], [5, 2], [2, 5], [5, 2], [2, 5]]]), [[3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1]])\nif N == 3: check('variant packet 3', solve(*[[[5, 2], [2, 5], [5, 2], [2, 5], [5, 2], [2, 5], [5, 2], [2, 5]]]), [[3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1]])\nif N == 4: check('variant packet 4', solve(*[[[5, 2], [2, 5], [5, 2], [2, 5], [5, 2], [2, 5], [5, 2], [2, 5], [5, 2], [2, 5]]]), [[3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1]])\nif N == 5: check('variant packet 5', solve(*[[[5, 2], [2, 5], [5, 2], [2, 5], [5, 2], [2, 5], [5, 2], [2, 5], [5, 2], [2, 5], [5, 2], [2, 5]]]), [[3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 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":"84bce7db30f6c43052c3f4cc54b4942abcfa7499105d1d9111b108b60728d06b","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\n\nN = 1\nobservations = []\ndef solve(pairs):\n    out=[]\n    for left,right in pairs:\n        side=left-right\n        half=int(side/2)\n        mid=right+half\n        parity=side&1\n        out.append([mid,side,parity])\n    return out\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\ncheck('oracle 1', solve(*([[5, 2], [2, 5]],)), [[3, 3, 1], [3, -3, 1]])\ncheck('oracle 2', solve(*([[0, 0], [1, 1]],)), [[0, 0, 0], [1, 0, 0]])\ncheck('oracle 3', solve(*([[-3, 2], [4, -1]],)), [[-1, -5, 1], [1, 5, 1]])\ncheck('oracle 4', solve(*([],)), [])\ncheck('oracle 5', solve(*([[1, 0], [0, 1]],)), [[0, 1, 1], [0, -1, 1]])\ncheck('oracle 6', solve(*([[7, 7], [-7, -7]],)), [[7, 0, 0], [-7, 0, 0]])\ncheck('oracle 7', solve(*([[3, 1], [-3, -1]],)), [[2, 2, 0], [-2, -2, 0]])\nif N == 1: check('variant packet 1', solve(*[[[5, 2], [2, 5], [5, 2], [2, 5]]]), [[3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1]])\nif N == 2: check('variant packet 2', solve(*[[[5, 2], [2, 5], [5, 2], [2, 5], [5, 2], [2, 5]]]), [[3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1]])\nif N == 3: check('variant packet 3', solve(*[[[5, 2], [2, 5], [5, 2], [2, 5], [5, 2], [2, 5], [5, 2], [2, 5]]]), [[3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1]])\nif N == 4: check('variant packet 4', solve(*[[[5, 2], [2, 5], [5, 2], [2, 5], [5, 2], [2, 5], [5, 2], [2, 5], [5, 2], [2, 5]]]), [[3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1]])\nif N == 5: check('variant packet 5', solve(*[[[5, 2], [2, 5], [5, 2], [2, 5], [5, 2], [2, 5], [5, 2], [2, 5], [5, 2], [2, 5], [5, 2], [2, 5]]]), [[3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 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":"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-mid-side-lifting-lifting-rounding","generated_at":"2026-09-29T14:44:58.588278+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":"Truncation toward zero differs from floor on negative odd side codes.","sha256":"1321a39c342af80ae24aa4e99c89f2eb23c7c2d0a73a87a96cbe68faa6daf663","title":"Pcm mid side lifting: lifting rounding · 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":42.783,"exit_code":1,"observations":[{"actual":[[4,3,1],[4,-3,1]],"check":"oracle 1","expected":[[3,3,1],[3,-3,1]],"passed":false},{"actual":[[0,0,0],[1,0,0]],"check":"oracle 2","expected":[[0,0,0],[1,0,0]],"passed":true},{"actual":[[0,-5,1],[2,5,1]],"check":"oracle 3","expected":[[-1,-5,1],[1,5,1]],"passed":false},{"actual":[],"check":"oracle 4","expected":[],"passed":true},{"actual":[[1,1,1],[1,-1,1]],"check":"oracle 5","expected":[[0,1,1],[0,-1,1]],"passed":false},{"actual":[[7,0,0],[-7,0,0]],"check":"oracle 6","expected":[[7,0,0],[-7,0,0]],"passed":true},{"actual":[[2,2,0],[-2,-2,0]],"check":"oracle 7","expected":[[2,2,0],[-2,-2,0]],"passed":true},{"actual":[[4,3,1],[4,-3,1],[4,3,1],[4,-3,1]],"check":"variant packet 1","expected":[[3,3,1],[3,-3,1],[3,3,1],[3,-3,1]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"oracle 1\", \"actual\": [[4, 3, 1], [4, -3, 1]], \"expected\": [[3, 3, 1], [3, -3, 1]], \"passed\": false}, {\"check\": \"oracle 2\", \"actual\": [[0, 0, 0], [1, 0, 0]], \"expected\": [[0, 0, 0], [1, 0, 0]], \"passed\": true}, {\"check\": \"oracle 3\", \"actual\": [[0, -5, 1], [2, 5, 1]], \"expected\": [[-1, -5, 1], [1, 5, 1]], \"passed\": false}, {\"check\": \"oracle 4\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"oracle 5\", \"actual\": [[1, 1, 1], [1, -1, 1]], \"expected\": [[0, 1, 1], [0, -1, 1]], \"passed\": false}, {\"check\": \"oracle 6\", \"actual\": [[7, 0, 0], [-7, 0, 0]], \"expected\": [[7, 0, 0], [-7, 0, 0]], \"passed\": true}, {\"check\": \"oracle 7\", \"actual\": [[2, 2, 0], [-2, -2, 0]], \"expected\": [[2, 2, 0], [-2, -2, 0]], \"passed\": true}, {\"check\": \"variant packet 1\", \"actual\": [[4, 3, 1], [4, -3, 1], [4, 3, 1], [4, -3, 1]], \"expected\": [[3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1]], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":43.556,"exit_code":1,"observations":[{"actual":[[3,3,1],[4,-3,1]],"check":"oracle 1","expected":[[3,3,1],[3,-3,1]],"passed":false},{"actual":[[0,0,0],[1,0,0]],"check":"oracle 2","expected":[[0,0,0],[1,0,0]],"passed":true},{"actual":[[0,-5,1],[1,5,1]],"check":"oracle 3","expected":[[-1,-5,1],[1,5,1]],"passed":false},{"actual":[],"check":"oracle 4","expected":[],"passed":true},{"actual":[[0,1,1],[1,-1,1]],"check":"oracle 5","expected":[[0,1,1],[0,-1,1]],"passed":false},{"actual":[[7,0,0],[-7,0,0]],"check":"oracle 6","expected":[[7,0,0],[-7,0,0]],"passed":true},{"actual":[[2,2,0],[-2,-2,0]],"check":"oracle 7","expected":[[2,2,0],[-2,-2,0]],"passed":true},{"actual":[[3,3,1],[4,-3,1],[3,3,1],[4,-3,1]],"check":"variant packet 1","expected":[[3,3,1],[3,-3,1],[3,3,1],[3,-3,1]],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"oracle 1\", \"actual\": [[3, 3, 1], [4, -3, 1]], \"expected\": [[3, 3, 1], [3, -3, 1]], \"passed\": false}, {\"check\": \"oracle 2\", \"actual\": [[0, 0, 0], [1, 0, 0]], \"expected\": [[0, 0, 0], [1, 0, 0]], \"passed\": true}, {\"check\": \"oracle 3\", \"actual\": [[0, -5, 1], [1, 5, 1]], \"expected\": [[-1, -5, 1], [1, 5, 1]], \"passed\": false}, {\"check\": \"oracle 4\", \"actual\": [], \"expected\": [], \"passed\": true}, {\"check\": \"oracle 5\", \"actual\": [[0, 1, 1], [1, -1, 1]], \"expected\": [[0, 1, 1], [0, -1, 1]], \"passed\": false}, {\"check\": \"oracle 6\", \"actual\": [[7, 0, 0], [-7, 0, 0]], \"expected\": [[7, 0, 0], [-7, 0, 0]], \"passed\": true}, {\"check\": \"oracle 7\", \"actual\": [[2, 2, 0], [-2, -2, 0]], \"expected\": [[2, 2, 0], [-2, -2, 0]], \"passed\": true}, {\"check\": \"variant packet 1\", \"actual\": [[3, 3, 1], [4, -3, 1], [3, 3, 1], [4, -3, 1]], \"expected\": [[3, 3, 1], [3, -3, 1], [3, 3, 1], [3, -3, 1]], \"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."}}